Inspection Procedures and Specifications for Pistons and Piston Pins {1214, 1214} Caterpillar

Caterpillar Products

All Cat Engines

Introduction

Table 1

Revision	Summary of Changes in SEBF8059
40	Added SN prefixes.
39	Removed Discontinued Part Number 174-6885 Cat Citra Soap
38	Added assembly procedure.
37	Combined information from SEBF8049, SEBF8051, SEBF8107, SEBF8150, SEBF8228, SEBF8290, SEBF8821, SEBF9106, SEBF9179, added 100 part numbers and repaired 72 pixelated illustrations.

© 2019 Caterpillar All Rights Reserved. This guideline is for the use of Cat dealers only. Unauthorized use of this document or the proprietary processes therein without permission may be violation of intellectual property law.

Information contained in this document is considered Caterpillar: Confidential Yellow.

This Reuse and Salvage Guideline contains the necessary information to allow a dealer to establish a parts reusability program. Reuse and salvage information enables Caterpillar dealers and customers to benefit from cost reductions. Every effort has been made to provide the most current information that is known to Caterpillar. Continuing improvement and advancement of product design might have caused changes to your product which are not included in this publication. This Reuse and Salvage Guideline must be used with the latest technical information that is available from Caterpillar.

For technical questions when using this document, work with your Dealer Technical Communicator (TC).

To report suspected errors, inaccuracies, or suggestions regarding the document, submit a form for feedback in the Service Information System (SIS Web) interface.

Important Safety Information

Illustration 1	g02139237

Work safely. Most accidents that involve product operation, maintenance, and repair are caused by failure to observe basic safety rules or precautions. An accident can often be avoided by recognizing potentially hazardous situations before an accident occurs. A person must be alert to potential hazards. This person should also have the necessary training, skills, and tools to perform these functions properly. Safety precautions and warnings are provided in this instruction and on the product. If these hazard warnings are not heeded, bodily injury or death could occur to you or to other persons. Caterpillar cannot anticipate every possible circumstance that might involve a potential hazard. Therefore, the warnings in this publication and the warnings that are on the product are not all inclusive. If a tool, a procedure, a work method, or operating technique that is not recommended by Caterpillar is used, ensure that it is safe for you and for other people to use. Ensure that the product will not be damaged or the product will not be made unsafe by the operation, lubrication, maintenance, or the repair procedures that are used.

Show/hide table

Improper operation, lubrication, maintenance or repair of this product can be dangerous and could result in injury or death. Do not operate or perform any lubrication, maintenance or repair on this product, until you have read and understood the operation, lubrication, maintenance and repair information.

Safety precautions and warnings are provided in this manual and on the product. If these hazard warnings are not heeded, bodily injury or death could occur to you or to other persons.

The hazards are identified by the safety alert symbol which is followed by a signal word such as danger, warning, or caution. The "WARNING" safety alert symbol is shown below.

Illustration 2	g00008666

This safety alert symbol means:

Pay attention!

Become alert!

Your safety is involved.

The message that appears under the safety alert symbol explains the hazard.

Operations that may cause product damage are identified by "NOTICE" labels on the product and in this publication.

Caterpillar cannot anticipate every possible circumstance that might involve a potential hazard. The safety information in this document and the safety information on the machine are not all inclusive. Determine that the tools, procedures, work methods, and operating techniques are safe. Determine that the operation, lubrication, maintenance, and repair procedures will not damage the machine. Also, determine that the operation, lubrication, maintenance, and repair procedures will not make the machine unsafe.

The information, the specifications, and the illustrations that exist in this guideline are based on information which was available at the time of publication. The specifications, torques, pressures, measurements, adjustments, illustrations, and other items can change at any time. These changes can affect the service that is given to the product. Obtain the complete, most current information before you start any job. Caterpillar dealers can supply the most current information.

Summary

This document will aid the technician in the visual inspection of multiple types of pistons and piston pins. It also covers multiple locations of pistons with many different wear and failure patterns. The piston or piston pins can be expected to give normal performance if the piston meets the specifications in this guideline. The piston must also be used in the same application.

Service Advisories, Service Letters, and Technical Information Bulletins

Show/hide table

NOTICE
The most recent Service Advisories and Service Letters that are related to this component should be reviewed before beginning work. Often Service Advisories, Service Letters, and Technical Information Bulletins contain upgrades in repair procedures, parts, and safety information which pertain to the components being repaired.

Canceled Part Numbers and Replaced Part Numbers

This document may include canceled part numbers and replaced part numbers. Use NPR on SIS for information about canceled part numbers and replaced part numbers. NPR will provide the current part numbers for replaced parts.

References

Table 2

References
Media Number	Publication Type & Title
SEBF8187	Reuse and Salvage Guidelines "Standardized Parts Marking Procedures"
SEBF8357	Reuse and Salvage Guidelines "General Cleaning Methods"
Reference Media URL https://channel1.mediaspace.kaltura.com/media/How+to+Measure+a+C175+Piston+Bore/1_06ro1gl7	Caterpillar Channel 1 Video "How to Measure a C175 Piston Bore"

Tooling and Equipment

Show/hide table

NOTICE
Failure to follow the recommended procedure or the specified tooling that is required for the procedure could result in damage to components. To avoid component damage, follow the recommended procedure using the recommended tools.

Table 3

Required Tooling and Equipment
Part Number	Description
1P-3537	Gauge Group
1U-7234	Feeler Gauge
1U-9029	Piston Ring Groove Gauge
1U-9030	Piston Ring Groove Gauge
3P-1568	Dial Indicator
4C-4997	Thread Tap 1/2 inch - 13 NC
4C-8164	Piston Ring Groove Gauge
4C-3654	Piston Ring Groove Gauge
4C-4804	Penetrant Oil
4C-8995	Ring Expander Group
4C-9442	Flashlight
4S-9405	Caliper
5P-1720	Seal Pick
5P-2170	Dial Bore Gauge Group
5P-3920	Steel Ruler
5P-7414	Seal Pick
6V-2032	Adapter
6V-2196	Microscope
6V-4876	Molybdenum Paste
6V-5067	O-ring
6V-6167	Contact Point
6V-7894	Microlite
8H-8577	Hammer
8H-8581	Feeler Gauge
8S-2257	Eye Loupe
8S-2328	Dial Indicator Group
8T-3033	Ring Expander Group
8T-5096	Dial Indicator Group
8T-7748	Deburring Wheel
8T-7765	Surface Reconditioning Pad
8U-8581	Feeler Gauge
9A-1593	Comparison Gauge
9S-8903	Indicator Contact Point
9U-6182	Inspection Mirror
162-5791	Shop Towels
174-6854	Cleaner
194-3514	Socket 22 mm 1/2 inch Drive
197-3710	Ring Groove Gauge
247-9763	Gage
262-8390	Pocket Microscope 40x
263-7184	Crack Detection Kit
288-4209	Paper Towel
327-8645	Ring groove gauge (Second/Intermediate Ring)
327-8645	Ring groove gauge (Oil Control Ring)
342-6241	Piston Gauge
367-9109	Digital Caliper
385-4008	Micrometer Tool Set, External 1524 mm (60 inch)
385-9422	Micrometer Extensions, Internal 50 - 609 mm (2 - 24 inch)
386-3364	Straight Edge
415-4055	Ultrasonic Tool Group
423-4373	Digital Caliper 0.0 - 203.2 mm (0.00 - 8.00 inch)
431-4150	Micrometer, External 25 mm (1 inch)
448-0722	17 mm Sideview Camera Borescope Probe
448-0723	5.5 mm HD Camera Borescope Probe
448-0724	Video Borescope - Wired Tool Group
448-0725	Video Borescope - Wireless Tool Group
459-0184	UV Lamp Group
473-8688 or 473-8689	Micrometer, Inside 2.00 - 12.00 inch
	Micrometer, Inside 50 - 300 mm
473-8690	Micrometer, Outside 0.00 - 4.00 inch
473-8691	Micrometer, Outside 2.00 - 6.00 inch
473-8691	Micrometer, Outside 50.8 - 152.4 mm (2.00 - 6.00 inch)
473-8692	Micrometer, Outside 152.4 - 304.8 mm (6.00 - 12.00 inch)
474-3709 or 474-3710	Micrometer, Inside (8.00 - 32.00 inch)
	Micrometer, Inside 200 - 800 mm
491-3146	Air Regulator Base
491-3253	Air Plug Assembly
510-5864	Ring groove gauge (Top Ring)
PC 9660™ (North & South America0 SF 7803™ (Europe, Africa & Middle East)	LOCTITE® Maxi-Coat Rust Inhibitor
SPX/OTC J36660	Tool
-	P-80 Assembly Lubricant

Replacement Parts

Consult the applicable Parts Identification manual for your engine.

Show/hide table

When replacement parts are required for this product Caterpillar recommends using Caterpillar replacement parts or parts with equivalent specifications including, but not limited to, physical dimensions, type, strength and material. Failure to heed this warning can lead to premature failures, product damage, personal injury or death.

Measurement Techniques

Show/hide table

NOTICE
Precise measurements shall be made when the component and measurement equipment are at 20° C (68° F). Measurements shall be made after both the component and measurement equipment have had sufficient time to soak at 20° C (68° F). This will ensure that both the surface and core of the material are at the same temperature.

Nomenclature of Pistons and Pistons Pins

Single Piece Forged Steel Piston Disassembly and Assembly Procedures

Illustration 3	g06297009
Piston and pin marking for orientation.

Before removing the piston pin and the piston, make sure to mark the piston, the pin, and the connecting rod with the corresponding rod number if the piston is being used again. The markings should be made so that the piston and the piston pin can be assembled exactly as taken apart. Mark the piston and the piston pin as shown in Illustration 3. When the piston and the piston pin are installed, the markings should line up again as before disassembly.

Illustration 4	g03219939
Straight piston pin

Illustration 5	g03219941
Piston pin with barrel shaped ends.

There are three types of piston pins: a straight pin (Illustration 4), a barrel shaped pin (Illustration 5), and a tapered pin (not shown). The ends of a barrel shaped pin has a cross section that resembles that of a barrel. The barrel end can easily be confused with a wear step. A tapered pin has a slight taper from the middle of the pin to the outside edge.

Disassembly Procedures for 3600, G3600, and C280 Piston

Note: Caterpillar does not recommend disassembly and subsequent assembly of the 3618 piston or gas piston. Disassembly and subsequent assembly should only apply to the diesel engine that has three and four piston rings.

Illustration 6	g06297011
Piston with single bolt

Illustration 7	g06297012
Piston with four studs and nuts

There are two basic styles of pistons. The current design for diesel engines incorporates a single bolt that retains the piston crown to the piston skirt. The former design for diesel engines incorporates four studs that are used to retain the piston crown to the piston skirt. The current design and original design for the gas engines incorporates four studs that are used to retain the piston crown to the piston skirt. There was a design for the gas engines that incorporated a single bolt to retain the piston crown to the skirt. Both of these types of pistons have two important characteristics that include a graphite coating on the nodular iron or on the aluminum skirt and an oil passage inside the steel crown.

Prior to the disassembly of the piston, permanently mark the crown and the skirt of each piston with an identification number or the identification numbers of the crown and skirt should be documented. Identification numbers are stamped on the outer rim of the crown and on the underside of the boss for the skirt. If pistons are marked, then the crowns should be marked on the top of the outer rim. Skirts should be marked on the bottom of the rim of the boss for the skirt. These steps will ensure that reusable crowns and skirts can be matched before placing the piston assembly in the engine. Refer to Reuse and Salvage Guideline, SEBF8187, "Standardized Parts Marking Procedures" for additional information.

• Avoid hard contact on the piston skirts.

• Do not use a mallet that is rubber or plastic to loosen the skirt from the crown.

• Do not hammer on the piston skirt.

• Remove the hardware that is on the underside of the skirt which is either one bolt or four nuts according to the piston design.

• Suspend the piston upside-down with a lifting strap.

• Use the brass rod by inserting the end through the central drain hole, and disassemble the piston with the aid of a hammer.

Disassembly Procedure For Single Bolt Three Ring Piston

1. Set the piston upside down on the crown. Clean the area around the bolt.
   Show/hide table

   Illustration 8	g02134336

2. Mark the skirt, spacer, and bolt head with a straight line across all of them.

3. Use a 32.0 mm (1.25 inch) socket to remove the bolt.

   Note: If the bolt was loose prior to the removal, the piston cannot be reused.

4. Separate the skirt from the crown.

5. Visually inspect the abutment faces for excessive wear. If no excessive wear is found, continue to the cleaning procedure.
   Show/hide table

   Illustration 9	g06297014
   Section view of the piston using depth micrometer (A) Inner edge measurement (B) Middle measurement

   Show/hide table

   Illustration 10	g06297015

6. Measure the wear step on the outer abutment joint in four places. The measurements should be taken 90° apart. Use a depth micrometer to measure down from the bottom of the crown to the inner edge of the abutment surface and then the middle of the surface. Be sure that all surfaces are cleaned with a non-abrasive procedure. If the difference between the two measurements is less than 0.10 mm (0.004 inch), the crown can be reused.

Illustration 11	g06297016

Measure the length (X) of the bolt to make sure that it has not stretched. The length of the bolt should be less than 81.4 mm (3.20 inch). If the length of the bolt exceeds the specification, use the 329-2411 Parts Kit to replace the bolt.

One-Piece Pistons

The graphite coating on the skirt helps to prevent scuffing and seizure during cold starting. The coating is dull, dark gray and the thickness is approximately 0.020 ± 0.004 mm (0.0008 ± 0.0002 inch). The purpose of the coating is similar to the lead tin overlay of a main bearing or a connecting rod bearing. The coating is put on the piston during the manufacturing process. There are no replacement coatings that can be applied outside of manufacturing. Be extra careful not to damage the coating during disassembly, cleaning, inspection, and assembly. It is important not to remove more of the graphite coating during the operation of cleaning.

The graphite coating will eventually wear off the surface of the piston during normal engine operation. This wear is normal and the wear will not create operational problems. Graphite coating can be worn from any portion of the piston but the coating is not typically worn from an area that is ± 40 degrees of the axis of the piston pin. The piston skirt must be smooth and free of any deep scratches and material built up.

The tops of some one-piece pistons have a hard anodized layer. This layer protects the top of the aluminum piston from the heat of combustion in high output engines. If the anodized layer is removed, the layer cannot be replaced. The anodized layer is not present on pistons that were manufactured after 1996. The crowns on two-piece pistons do not have the anodized layer. The oil passage, which is used for cooling, runs along the circumference of the crown. The location of the oil passage can be found by locating the holes in the bottom of the piston. The slot for lubricating the piston pin in each piston pin bore is also an oil passage.

Note: During cleaning of the piston with glass beads, close all oil passages to keep out debris.

Illustration 12	g01984853
Aluminum one piece direct injection piston with a single compression ring. (1) Crown (2) Crater (3) Ring Band (4) Ring Grooves (5) Ring Lands (6) Skirt (7) Pin Bore (8) Snap Ring Groove (9) Top Land (10) Skirt Relief

Illustration 13	g01984976
Aluminum one piece direct injection piston with a double ring land. (1) Crown (2) Crater (3) Ring Band (4) Ring Grooves (5) Ring Lands (6) Skirt (7) Pin Bore (8) Snap Ring Groove (9) Top Land (10) Cooling Jet Relief (11) Skirt Relief

Illustration 14	g01985115
Aluminum one piece direct injection piston with a single ring land. (1) Crown (2) Crater (3) Ring Band (4) Ring Grooves (5) Ring Lands (6) Skirt (7) Pin Bore (8) Snap Ring Groove (9) Top Land (10) Cooling Jet Relief (11) Skirt Relief

Illustration 15	g01985274
Aluminum one piece piston from a 3500 series engine. (1) Crown (2) Crater (3) Ring Band (4) Ring Grooves (5) Ring Lands (6) Skirt (7) Pin Bore (8) Snap Ring Groove (9) Top Land

Illustration 16	g01985293
The piston from a typical precombustion chamber engine (1) Crown (2) Crater (3) Ring Band (4) Ring Grooves (5) Ring Lands (6) Skirt (7) Pin Bore (8) Snap Ring Groove (9) Top Land (10) Cooling Jet Relief (11) Skirt Relief (12) Relief for Valve (13) Heat Plug

Forged Steel Pistons

Illustration 17	g01275611
Forged Steel Piston with Single Piece

Graphite Coating

Many of the new one-piece pistons have two important characteristics. The characteristics are graphite coating on the skirt and an oil passage inside the crown. Refer to Illustration 18. The graphite coating is not present on pistons that were manufactured after 1996.

Illustration 18	g01947686
(7) Bore surface of piston pin (13) Graphite coating (14) Passage for oil cooling of crown (15) Vertical oil passage

Illustration 19	g06297018
One piece piston with a coating of graphite Refer to "Graphite Coated Pistons" later on in this document for more information. (1) Crown (2) Crater (3) Ring Grooves (4) Top Land (5) Ring Lands (6) Piston Pin Bushing (7) Skirt (8) Pin Bore in Skirt (9) Piston Side Relief

Note: The piston and piston pin must be identified and marked with the cylinder number and orientation in reference to the front of the engine.

Note: Do not mix and match pistons and piston pins from different cylinders. Ensure that the pistons and piston pins are oriented properly to the front of the engine upon reassembly.

Show/hide table

NOTICE
Piston and piston pins wear together, mixing the parts may lead in pin seizures.

Illustration 20	g06297095
This color coded piston shows the risk/stress areas of the piston. Illustration 20 is a one piece graphite coated piston but applies to all pistons. (1) Red - High risk/stress area of the piston. (2) Yellow - Medium risk/stress area of the piston. (3) Green - Low risk/stress area of the piston.

Anodized Layers

The tops of some one-piece pistons have a hard anodized layer. This layer protects the top of the aluminum piston from the heat of combustion in high output engines. If the anodized layer is removed, the layer cannot be replaced. The anodized layer is not present on pistons that were manufactured after 1996. The crowns on two-piece pistons do not have the anodized layer.

Oil Passages

The oil passage, which is used for cooling, runs along the circumference of the crown. The holes for the oil passage can be found in the bottom of the piston. The holes can also be found in the slot for lubricating the piston pin in each piston pin bore.

Steel Crown and Aluminum Skirt

This style is regarded as a one-piece piston assembly because the assembly should not be separated into two pieces. Do not separate the crown from the skirt. It has two important characteristics: a graphite coating on the aluminum skirt and a separate steel crown.

Illustration 21	g06297098
Section view of piston identifying crown, skirt, and all oil passages. (1) Crown (2) Crown oil cooling passage (3) Center oil return passage (4) Bottom oil ring lube passage (5) Piston pin lube spot (6) Cooling jet supply passage (7) Crown and skirt joint (A) Graphite coating

Show/hide table

NOTICE
Never disassemble the crown from the skirt. The pistons are assembled at the factory using special procedures and the crowns are matched with the skirts. This procedure cannot be duplicated in the field. Special procedures and tooling are required to tighten the bolts holding the crown to the skirt. Do not attempt to check or retighten the bolts.

The graphite coating on the skirt helps to prevent cold start scuffing and seizure. The coating is approximately 0.020 ± 0.004 mm (0.0008 ± 0.0002 inch) thick, dull (not shiny) and dark gray. The coating has a purpose like the lead-tin overlay on an engine bearing. The coating is put on the piston during manufacture. There are no replacement coatings that can be applied in the field. Be extra careful not to damage any of the coating during cleaning and inspection.

The graphite coating will eventually wear off the piston surface where the piston contacts the liner. This wear is normal and will not create problems. Do not remove more of the graphite coating during the cleaning operation. The coating can be worn on any portion of the piston. The piston skirt must be smooth and free of any deep scratches and material build-up.

Two-Piece Pistons

Illustration 22	g06297102
Features of a two-piece piston crown and skirt (1) Crown (2) Crater (3) Ring grooves (4) Top land (5) Ring lands (6) Piston Pin Bushing (7) Skirt (8) Piston pin bore (9) Side relief for piston

Cleaning Procedure of Pistons and Piston Pins

Make a quick visual inspection of the piston before cleaning. If no obvious faults are found, clean the piston.

Solvent

Clean any engine piston that is made by Caterpillar with high quality, biodegradable solvents. Remove all carbon deposits with a solvent that does not affect the aluminum in the pistons.

Glass Beads

Use this method only when the preferred method is ineffective. Cleaning the piston with glass beads requires certain precautions. Glass beads can alter the dimensions of the piston. The beads can hide cracks during visual inspection also.

Never clean the piston with glass beads which are larger than 230 microns (0.009 inch). Glass beads of size 10 are 88 microns (0.0035 inch) to 149 microns (0.0095 inch) and air pressure of 550 kPa (79.7720 psi) to 620 kPa (89.9248 psi) are used to achieve the desired results. Glass beads of size 9 are 125 microns (0.0049 inch) to 177 microns (0.0070 inch) and beads of size 11 are 75 microns (0.0029 inch) to 125 microns (0.0049 inch). Sizes 9 through 11 are also acceptable. Change the glass beads and check the nozzle regularly for best results.

Follow these guidelines to clean pistons with glass beads.

1. Do not use aluminum oxide or an abrasive material in place of glass beads.

2. Do not use a wire brush or a wire wheel.

3. Do not use steel shot.

4. The method of using glass beads can push a small amount of material from the ring band into the ring groove. This material can be felt with a fingernail. If the material is not removed, the ring will not move freely in the groove. Remove this material carefully with a triangular file or a flat file. Do not put a chamfer on either side of the ring groove.

5. Glass beads that are larger than the recommended size or driven under excessive air pressure can smear material over cracks. The smeared material can cover cracks that cause visual inspections for cracks to be difficult.

One-Piece Pistons

The crowns may be cleaned with glass beads. However, several areas of the piston must be protected from the glass beads. Refer to Illustration 23.

Note: After the piston is cleaned, check the oil passages. Make sure that all passages and other areas are free of debris or glass beads. Foreign material on the piston can be washed into the lubrication system and can damage other engine components.

Use an O-ring to protect the oil ring groove.

Illustration 23	g01275647
Areas which need protection from glass beads on one-piece pistons (7) Piston pin bore (21) Sharp edge of crater (22) Outer edge of piston crown (23) Oil ring groove (24) Oil passages

Piston Skirt with Graphite Coating

Clean the graphite coating on the piston skirt with a solution of liquid detergent and water. The graphite coating can be cleaned with water and a solution of liquid detergent which contains little chlorine content.

Put the piston into this solution with enough time to loosen carbon and oil deposits. Remove the piston when the piston is clean. To clean the skirt faster, heat the solution to a temperature near 55 °C (131 °F).

Note: If more than 50% of the graphite coating is missing from the skirt, the piston is no reusable

Never use glass beads to clean the skirt (Illustration 24) or the oil ring groove. Use a small brush to brush the oil ring groove with previously used soap and water.

Illustration 24	g01275369
Damage of the skirt below the oil ring groove may be caused by glass beads.

Protect any graphite coating. Place a protective cover over the skirt and the oil ring groove. Illustrations 25,26,27, and 28 show the areas that need protection from glass beads. (Glass beads must not get into the oil passages.)

Illustration 25	g01275653
Protect oil holes from damage by glass beads. These holes are indicated by the arrows.

Illustration 26	g01275662
Protect oil holes from damage by glass beads on forged steel pistons. These holes are indicated by the arrows.

Test the strength of the plates in the cooling gallery. If either plate becomes loose, do not use the piston again.

Illustration 27	g01275679
Areas that need protection from glass beads (7) Bore surface of piston pin (13) Graphite coating (17) Slot for lubrication of piston pin

Illustration 28	g01275696
Areas on the forged steel piston with single piece that need protection from glass beads (7) Bore surface of piston pin (13) Graphite coating

Use an O-ring as protection for the oil ring groove and the top of the graphite coating. Refer to Illustration 29.

Illustration 29	g01275707
O-ring in position

Illustration 30	g01275722
Fabricated fixture for cleaning (25) O-ring for protection of oil ring land (26) Cylinder liner (27) Base plate

For maximum protection, fabricate a fixture for cleaning (Illustration 30). In addition to the O-ring, the two other items that make up the fixture for cleaning are an old liner and a cover plate that can be welded to the liner. Illustration 31 shows an alternate fixture that makes cleaning pistons faster and easier.

Illustration 31	g01275792
This alternate fixture for cleaning has an angled design with rotating capability which makes cleaning pistons faster and easier. (25) O-ring for protection of oil ring land (26) Cylinder liner (27) Base plate (28) Bearing for air compressor (29) Tubing (30) Bottom plate for liner

Illustration 32	g01275800

After cleaning the piston with glass beads, use air pressure to remove debris that entered the oil passages of the piston. Refer to Illustration 32. Wash the piston again with the solution for cleaning. Apply a rust preventive to the iron ring band to prevent rusting.

Piston Crown with Anodized Layer

Some one-piece pistons have a hard, anodized layer on top of the pistons. This layer protects the top of the aluminum piston from the heat of combustion. The layer will last as long as the life of the piston during normal operating conditions. If the layer is removed, the layer cannot be replaced. On one-piece pistons, the glass beads cannot be used to clean the top of the piston or the skirt. Cover the top of the piston when glass beads are used to clean the ring grooves. Refer to Illustration 33.

Illustration 33	g01275802
Protect the skirt and top of piston from glass beads.

Due to structural improvements to the oil gallery and the piston crown, the anodized layer is no longer necessary. The piston has a coating which is a mixture of phosphate and graphite. This mixture has been shown to be ineffective by data from the field and laboratory.

The new piston without the anodized layer and phosphate and graphite coating can be interchanged with the earlier made piston that contains these two features. The pistons with the coating and the pistons without the coating can be distinguished only by a difference in color. Refer to Illustration 34 and Illustration 35. The difference in color has no effect on the ability to use the pistons.

Pistons without the anodized layer can be cleaned without the cap that is required for the anodized piston. Follow all these guidelines for cleaning the pistons without the anodized layer. Anodized Pistons must follow the same guidelines for protection of the anodized layer and coating of a mixture of phosphate and graphite.

Illustration 34	g01275805
Old style of an anodized piston with coatings of a mixture of phosphate and graphite

Illustration 35	g01275810
New piston with no anodized layer or coating of a mixture of phosphate and graphite

To clean the tops of pistons with an anodized layer, use a solution of hot water and soap in the same way as cleaning the skirts. Water may be used to clean the piston crown.

Protect the anodized layer of the piston with a plastic cap when you clean the piston with glass beads. The size of the cap is determined by the diameter of the piston and the depth of protection needed.

Piston Cooling Jets

Illustration 36	g06177275

Make sure that screen (1) of the cooling jet is clean and free of debris. Tubes (2) should be free of impact marks that could have been made during the removal of the cylinder pack.

Pistons with Steel Crown and Aluminum Skirt

The piston has four ring grooves at the top of the assembly. The top two ring grooves are machined in the steel crown. The bottom two ring grooves are machined in the aluminum skirt. Be sure to use different methods and procedures to clean each material (steel and aluminum). Clean the steel crown with a chemical solution to remove carbon build-up. Clean the aluminum skirt with a solution of liquid detergent and water to prevent damage to the graphite coating.

Protect Oil Passages

Tape or plug the oil passages, used for feeding the crown area and the bottom oil ring, when using glass beads. The locations of the oil passages are:

• The hole on the bottom of the piston skirt which feeds the piston pin

• The four cross drilled holes from the bottom ring groove to the inside diameter of the piston

• The hole in the center of the bottom side of the piston crown and the piston pin lube slot in one piston pin bore

• For 3600 pistons check the holes that are in the top of the piston as the threads might need to be lightly tapped due to carbon or debris buildup. This will ensure that the lifting hole threads will not be damaged. Use a Thread Tap that is 1/2 inch 13 NC to tap the lifting holes.

Earlier production pistons may have four lube slots in the pin bore.

Protection for the Graphite Coating

During glass beading, protect the graphite coating on the skirt and the bottom two ring grooves. Let the protective cover slightly overlap the crown and skirt joint. There will be a small open joint approximately 0.5 mm (0.02 inch) at the parting line of the crown and the skirt. This cover will eliminate the possibility of glass beads becoming lodged in this opening.

Several methods can be used to protect the graphite coating on the bottom of the aluminum skirt. The methods are:

• Tape

• Shim stock with band clamp.

• Rubber tubing

• O-ring for the oil ring groove

A used liner or cylinder the size of the piston with a stop to position the piston with only the top two ring grooves exposed above the mating joint surface of the crown and skirt.

Cleaning The Aluminum Skirt

The aluminum surface of the graphite-coated skirt can be cleaned with a solution of liquid detergent, with little or no chlorine content, and water. 174-6885 Cleaner is a good detergent to use. Mix 237 mL (8.0 oz) of liquid with every 7.6 L (2.0 US gal) of water ( 240 mL (8.2 oz) per 3.8 L (1.0 US gal).

Let the piston stand in this solution, normally one to two hours, to loosen carbon and oil deposits. Remember, too much time in the solution may damage the graphite coating. Remove the piston when the piston looks clean. To clean the skirt faster, heat the detergent water solution to 55 ° C (131 ° F). flush the oil passages with a pressure washer.

Note: If more than 50% of the graphite coating is missing from the skirt, the piston is not reusable.

Show/hide table

NOTICE
Never use glass beads to clean the graphite-coated skirt and the bottom two piston ring grooves. Clean the bottom two ring grooves in the aluminum skirt with a small brush that has nylon bristles. Use the same solution of soap and water.

Cleaning The Steel Crown

The steel crown can be cleaned with a chemical solution or glass beads. Flush the oil passages with a high-pressure washer and 1U-5490 Cleaner to remove any contaminates from oil passages.

When using glass beads to clean pistons, protect the following from bead damage: the graphite coating, the pin bore surface, and the lube slot in the piston pin bore. Tape all surfaces and oil passages to prevent damage or beads from entering the passages.

When using glass beads to clean the crown and ring grooves, follow these requirements:

• Use size 10 glass beads, 88 to 149 microns (0.0035 to 0.0059 inch) under 620 kPa (80 to 90 psi) air pressure to provide the best results.

• Never use glass beads larger than 230 microns (0.0091 inch) to clean any part of the piston.

• Change the glass beads and check the condition regularly for best results.

Show/hide table

NOTICE
1. Do not use aluminum oxide or any other abrasives instead of (or mixed with) glass beads. 2. Do not use steel shot. 3. The glass bead method may force a small amount of material into the ring groove. If this material can be felt with the fingernail, remove the material with a three-cornered file. Failure to do this, will prevent the ring from moving freely in the groove. Do not put a chamfer on either side of the ring groove.

Oil Passage Holes In The Piston

Flush all oil passages and outside ring surfaces with clean engine oil before storage or installation into the engine. Store the pistons by covering them with sheets of plastic after cleaning.

Show/hide table

NOTICE
It is important to check all the oil passages after the piston is cleaned, making sure that the passages are free of debris or glass beads. Any foreign material left in the oil passages will be washed out later into the engine lubrication system and damage engine components.

Two-Piece Pistons

The two-piece piston crowns may be cleaned with glass beads. However, several areas of the piston must be protected from the glass beads. Refer to Illustration 37.

Illustration 37	g01275823
Areas which need protection from glass beads on two-piece pistons (7) Bore surface of piston pin (21) Sharp edge of crater (22) Outer edge of piston crown (31) Lower edge of crown

Use an O-ring to protect the oil ring groove.

After cleaning the piston with glass beads, use air pressure to remove debris that entered the oil passages of the piston. Wash the piston again after cleaning with glass beads. Apply the rust preventive to the crown of the two-piece piston.

Piston Pins

Prior to conducting a visual inspection the piston pins must be cleaned. A good solvent can normally remove deposits of dirt and oil, but the solvent will not remove discoloration. While discoloration is acceptable for reuse, some discoloration can be removed with the 8T-7748 Deburring Wheel. Refer to Illustrations 38,39, and 40.

Note: Do NOT use this type of cleaning on coated piston pins.

Note: Piston pins do not need to be cleaned if the surfaces of the pins are smooth and the surfaces have an acceptable surface texture.

Illustration 38	g01249749

Use only 8T-7748 Deburring Wheel to clean the discoloration from the piston pins. If 8T-7748 Deburring Wheel is used properly, then the surface texture will not be damaged.

Use only the 8T-7748 Deburring Wheel that is installed with two 6V-2032 Adapters to clean the piston pin.

Illustration 39	g01249771

The discoloration around the circumference of the piston pin is acceptable if the surface is still smooth.

Illustration 40	g06297108

Note: Do not use the 6V-2033 Polishing Brush which looks like the 8T-7748 Deburring Wheel. See Illustration 38.

If the deburring wheel is used correctly, metal will not be removed and the correct surface texture of 0.125 µm (5.0000 µinch) will be maintained.

The 8T-7748 Deburring Wheel has an outer diameter of 203.2 mm (8.00 inch). The inner diameter is 76.2 mm (3.00 inch). The width is 25.4 mm (1.00 inch). If necessary, the 12.7 mm (0.50 inch) pilot hole on 6V-2032 Adapter can be made larger. Two wheels can be installed together for more width. Use a piece of 76.0 mm (3.00 inch) tubing to hold the wheels together. Check the information on the wheel for the correct maximum revolutions per minute (RPM) for operation. Then check the RPM of the grinder. It is important to turn the piston pin slowly against the wheel. Do not hold the piston pin in the same position for more than five seconds. The finish must be even in smoothness around the piston pin.

Initial Inspection

Follow the instructions in this guideline to determine if a piston is reusable.

1. Make a visual check of the overall condition of the piston.

2. Reinspect the piston after cleaning for the following.

   • Cracks

   • Scuffing

   • Holes

   • Additional visible damage from poor handling

   • Imbedded material

   • Excessive wear of the graphite coating

3. The following areas of the piston should be inspected before reusing.

   • Crater

   • Crown

   • Pin Bore

   • Ring Groove

   • Ring Lands

   • Skirt

   • Snap Ring Groove

   • Structure

Fuel Erosion and Pitting in the Crater

Illustration 41	g02776917
Signs of carbon buildup from fuel deposits but no pitting is present. This piston may be used again after proper cleaning. USE AGAIN

Illustration 42	g02776921
Signs of carbon buildup from fuel deposits but no pitting is present. This piston may be used again after proper cleaning. USE AGAIN

Illustration 43	g02776920
Heavy carbon deposits, but no pitting in the metal is visible. Clean the piston and inspect again. USE AGAIN

Illustration 44	g02776859
Signs of carbon buildup from fuel deposits but no pitting is present. No damage to the crown is visible and no cracks are visible. This piston may be used again after proper cleaning. USE AGAIN

Illustration 45	g02776858
Minimal fuel erosion is visible after the piston has been cleaned. USE AGAIN

Illustration 46	g02776839
Fuel erosion is slightly deeper and can be felt with fingernail after cleaning. This is acceptable if the erosion does not spread across 25% of the piston. USE AGAIN

Illustration 47	g06297111
The crater of the piston shows deep erosion that is caused by fuel. DO NOT USE AGAIN

Illustration 48	g06297125
Deep uneven erosion caused by fuel. DO NOT USE AGAIN

Illustration 49	g06297130
The crater of the piston is showing multiple points of deep erosion that is caused by fuel. DO NOT USE AGAIN

Illustration 50	g02776841
Light pitting in a low stress area of the piston. USE AGAIN

Illustration 51	g02776856
Minimal pitting that is consistent across the piston. USE AGAIN

Illustration 52	g02776848
Fuel erosion has caused visible pitting in the crater but the pitting is minimal. USE AGAIN

Illustration 53	g02776844
Small concentration of light pitting in a low stress area of the piston. USE AGAIN

Illustration 54	g02776845
Heavy deep pits. DO NOT USE AGAIN

Illustration 55	g03386431
This piston shows excessive pitting that exhibits increased intensity from left to right. DO NOT USE AGAIN

Illustration 56	g02776849
Deep aggressive pits in the spray pattern. DO NOT USE AGAIN

Illustration 57	g02776847
Multiple points of erosion in a high stress area of the piston. DO NOT USE AGAIN

Illustration 58	g02776851
Concentrated deep pits and erosion. DO NOT USE AGAIN

Illustration 59	g02776853
Deep erosion and pitting in one centralized location. DO NOT USE AGAIN

Illustration 60	g02776855
Deep erosion and pitting in one centralized location. This is a close up view of Illustration 59 DO NOT USE AGAIN

Illustration 61	g02776931
Multiple deep pits across the entire piston. DO NOT USE AGAIN

Illustration 62	g02776850
Erosion and pitting across the entire piston. DO NOT USE AGAIN

Illustration 63	g06297136
Multiple pits and erosion across the entire piston. DO NOT USE AGAIN

Illustration 64	g06297141
The piston has heavy erosion on the crown. Any piston that is displaying this severity of erosion anywhere on the crown should not be reused. DO NOT USE AGAIN

Crown

Illustration 65	g02776928
Light pitting. USE AGAIN

Illustration 66	g02776929
Light concentration of pitting on one location of the piston. USE AGAIN

Illustration 67	g02776922
Light pitting in one area of the piston. USE AGAIN

Illustration 68	g06297142
The piston crown is showing numerous deep pits and distinct pits.

DO NOT USE AGAIN

Illustration 69	g02776930
This piston shows multiple deep and shallow pits that extend near the bowl rim. Pits on the edge of the combustion bowl are not allowed. DO NOT USE AGAIN

Illustration 70	g02776923
A large concentration of small and larger pits in one area of the piston. These pits are too close to the bowl. DO NOT USE AGAIN

Illustration 71	g02776924
Concentration of shallow pitting transferring into deep pitting. DO NOT USE AGAIN

Illustration 72	g02776927
Deep pitting on the crown. DO NOT USE AGAIN

Illustration 73	g02776926
Deep pitting over a large area of crown and into the crater. DO NOT USE AGAIN

Illustration 74	g02817942
Mild impact damage with no imbedded material. No cracks are present and no damage is on corners of crown. This piston can be reused after salvage and inspection. USE AGAIN

Illustration 75	g02817944
Mild impact damage with no imbedded material. No cracks are present. This piston can be reused after salvage and inspection. USE AGAIN

Illustration 76	g02776933
Mild impact from valve with no imbedded material and no cracks are present. USE AGAIN

Illustration 77	g02821348
Mild impact from valve with no imbedded material and no cracks are present. USE AGAIN

Illustration 78	g02817960
Mild impact from valve. USE AGAIN

Illustration 79	g02817950
Impact damage from valve with light raised material. The impact does not show the impression of the entire valve. This piston can be reused after salvage and inspection. USE AGAIN

Illustration 80	g02817959
Impact damage from valve. Do not reuse any piston showing the entire valve impression with raised material. DO NOT USE AGAIN

Illustration 81	g02817947
Heavier impact damage from valve that runs out to the bowl. DO NOT USE AGAIN

Illustration 82	g02817945
Heavy impact damage from multiple valves. DO NOT USE AGAIN

Illustration 83	g02817961
Heavy impact damage with raised material. DO NOT USE AGAIN

Illustration 84	g02820178
Heavy impact damage with raised material. DO NOT USE AGAIN

Illustration 85	g02820181
Heavy impact damage with deep pits and imbedded material. DO NOT USE AGAIN

Illustration 86	g02820182
Heavy impact damage with deep pits. DO NOT USE AGAIN

Illustration 87	g02820183
Heavy impact damage with deep pits. DO NOT USE AGAIN

Single Bolt Three Ring Piston for 3600, G3600, and C280

Illustration 88	g02134688
Reuse the piston.

Illustration 89	g02134855
Reuse the piston.

Illustration 90	g02135676
Reuse the piston.

Illustration 91	g02135697
Reuse the piston.

Four Ring Piston for 3600, G3600, and C280

Pilot Diameter Of The Piston Skirt

Illustration 92	g06297147
Marks due to machining

Reuse the piston skirt.

Illustration 93	g06297149
Burrs

Do not reuse the piston.

Use the piston again after the burrs are removed.

Illustration 94	g06297150
Too much fretting and smearing

Do not reuse the piston.

Illustration 95	g06297151
Burrs

Reuse the piston.

Use the piston again after the burrs are removed.

Main Abutment Of The Piston Skirt

Illustration 96	g06297152
Use the piston again if the nuts were tight during the disassembly of the piston.

Reuse the piston.

Illustration 97	g06297155
Too much fretting and smearing

Do not reuse the piston.

Illustration 98	g06297156
This is a typical appearance.

Reuse the piston.

Illustration 99	g06297158
Remove any burrs.

Reuse the piston.

Illustration 100	g06297162
Excessive fretting

Do not reuse the piston.

Outer Abutment Of The Piston Skirt

Illustration 101	g06297163
Initial stages of a piston that is cracking with material that is being torn from the inner edge of the outer abutment are for the joint.

Do not reuse the piston.

Illustration 102	g06297164
Remove any burrs before reassembling the piston.

Reuse the skirt.

Illustration 103	g06297175
Acceptable level of fretting

Reuse the piston.

Illustration 104	g06297178
The outer abutment has too much fretting. The main abutment has fretting that is advanced too much, even though the fretting is localized.

Do not reuse the piston.

Piston Crown

Illustration 105	g06297180
Too much fretting

Do not reuse the piston.

Illustration 106	g06297183
The piston in this example has fretting that is excessive, damage from debris, damaged bolt holes, and heavy contact on the outside of the outer abutment.

Do not reuse the piston.

Illustration 107	g06297185
Excessive fretting

Do not reuse the piston.

Illustration 108	g06297189
A wear pattern that is acceptable

Reuse the piston.

Illustration 109	g06297190
A wear step that is worn into the outer abutment with contact outside the outer abutment and excessive deposits under the crown

Do not reuse the piston.

Illustration 110	g06297194
Contact of the edge is evident at the outside diameter of the piston.

Do not reuse the piston.

Illustration 111	g06297198
Excessive deposits under the crown, contact at the outside diameter at six to eight o'clock and excessive fretting of the outer abutment

Do not reuse the piston.

Pin Bore

During the visual inspection of the piston pin bore, carefully inspect the snap ring groove of the piston for damage or wear. Do not use the piston again if the groove is excessively worn or damaged. Pistons should be checked in the snap ring groove for undetected wear by comparing the fit of the snap ring in the old piston and in a new piston. The piston should not be reused if the effort to turn the snap ring in the used piston is significantly less than the new piston.

Note: Orientation of the piston and piston pin is critical especially with one piece graphite coated pistons. Keep the pins orientated exactly how the pins were removed from the pistons. Failure to do so may lead to pin seizure and engine failure.

Illustration 112	g02821938
Slight wear in retaining ring groove. USE AGAIN

Illustration 113	g02821939
Small damage to the ring groove. USE AGAIN

Illustration 114	g02821940
Slight wear to pin bore. USE AGAIN

Illustration 115	g02821957
Slight wear in the ring groove from installation or removal of the snap ring. USE AGAIN

Illustration 116	g02821956
The machining grooves are no longer visible in the ring groove. This piston pin bore is worn. DO NOT USE AGAIN

Illustration 117	g06297203
The piston has light wear on the edge of the bore, but the measurements of the bore are correct. USE AGAIN

Illustration 118	g06297204
The piston has discoloration on the bottom of the piston. Measure the piston pin bores to make sure that there is no distortion. USE AGAIN

Use the piston again.

Illustration 119	g06297206
The piston has a wear pattern inside the pin bore. USE AGAIN

Illustration 120	g06297208
The piston shows wear and light scratches in the pin bore that cannot be felt with a fingernail. USE AGAIN

Illustration 121	g02827245
Slight wear/discoloration on bushing. USE AGAIN

Illustration 122	g02827241
Slight discoloration on bushing. USE AGAIN

Illustration 123	g02831059
Small scratch to bushing that can be felt with a fingernail. DO NOT USE AGAIN

Illustration 124	g02831062
Chaining abrasive wear to bushing. DO NOT USE AGAIN

Illustration 125	g02827239
Tempering to the bushing. DO NOT USE AGAIN

Illustration 126	g02827238
Polishing to the bushing. DO NOT USE AGAIN

Illustration 127	g02831057
Slight tempering and polishing to the bushing. DO NOT USE AGAIN

Note: If piston pin bushing has worn through the phosphate coating, it is out of specification and must be replaced. Failure to replace the piston once the coating is worn away can result in piston pin seizure and engine failure.

Illustration 128	g02831064
Phosphate coating worn. DO NOT USE AGAIN

Illustration 129	g02831069
Phosphate coating worn. DO NOT USE AGAIN

Illustration 130	g02833158
Phosphate coating worn. DO NOT USE AGAIN

Illustration 131	g02833159
Phosphate coating worn. DO NOT USE AGAIN

Illustration 132	g02833161
Phosphate coating worn. DO NOT USE AGAIN

Illustration 133	g02833163
Phosphate coating worn. DO NOT USE AGAIN

Illustration 134	g02827249
Phosphate coating worn and pitting starting in the bushing. DO NOT USE AGAIN

One-Piece Aluminum Pistons

Some one-piece pistons have circular pin bores. Other one-piece pistons have oval pin bores. This wear pattern is formed by a side relief on both ends of the horizontal diameter. Refer to Illustration 135. The vertical diameter must be within specifications in Table 5 but the horizontal diameter must only be larger than the vertical diameter.

Illustration 135	g01276021
Pistons with a side relief should be measured at location 32 only. (11) Side relief for piston (33) Dimension 33 will be larger than dimension 32 by 0.030 mm (0.0012 inch) to 0.045 mm (0.0018 inch).

Note: The pin bore diameter of newer one-piece pistons are elliptical. Be sure that dimension (33) is larger than dimension (32).

Two-Piece Pistons and One-Piece Steel Pistons

Piston pin bore diameter (32) on all two-piece piston crowns is in Table 5. The pin bore diameter (34) must be measured. Illustration 136 shows the measurement locations.

Illustration 136	g01276035
Measurement locations for the new piston crown pin bore diameter. (34) Refer to Table 5 for this dimension.

Inspect Bushings of Crown for Two-Piece Pistons and for One-Piece Steel Pistons

Inspect the bushing of two-piece piston crowns for rotation. If the bushing has damage from debris or if there is rotation of the bushing, the crown cannot be reused. See Illustration 137 as an example for rotation of the bushing.

Illustration 137	g01276054
The bushing of a two-piece piston crown has rotated.

Do not use the piston again.

Illustration 138	g01276056
Enlarged view of Illustration 137 which shows rotation of bushing

Do not use the piston again.

Procedure to Measure Piston Pin Bores for C175 Pistons

Show/hide table

NOTICE
Precise measurements shall be made when the component and measurement equipment are at 20° C (68° F). Measurements shall be made after both the component and measurement equipment have had sufficient time to soak at 20° C (68° F). This will ensure that both the surface and core of the material is at the same temperature.

Illustration 139	g06185716
View of air gage.

An air gage is the only method for measuring pin bore.

It is not necessary to check the piston pin bore diameter if the piston pin has been found with rotation that was easy during disassembly. If a piston has been in an engine event which has caused force against the piston, check the pin bore for distortion.

Refer to manufactures operating manual for step by step instructions setup and measuring the pin bore.

To provide addition clarification and details, a Caterpillar Channel 1 video has been created outlining the critical steps in measuring the piston bore. Reviewing the videos is recommended prior to starting the measuring process.

Note: A CWS login is required to access Caterpillar Channel 1 Videos.

Table 4

Caterpillar Channel 1
Title:	"How to Measure a C175 Piston Bore"
Caterpillar Channel 1 URL:	https://channel1.mediaspace.kaltura.com/media/How+to+Measure+a+C175+Piston+Bore/1_06ro1gl7

Ring Grooves

Note: Measuring ring grooves can consume a considerable amount of time. Make sure that the piston is reusable by all other measurements and criteria before performing the procedure to measure piston ring grooves.

Note: All piston ring grooves that show any wear steps must be measured.

Illustration 140	g06177284
Identification of piston ring grooves (12) Top piston ring (13) Intermediate piston ring (14) Oil control piston ring

Illustration 141	g02833886
Small wear step. USE AGAIN

Illustration 142	g02833885
Large wear step. DO NOT USE AGAIN

Illustration 143	g02833879
Carbon in the ring groove. Clean the piston again and reinspect. This piston is reusable if the carbon can be removed. USE AGAIN

Illustration 144	g02833877
Corrosion on the top ring grove. DO NOT USE AGAIN

Illustration 145	g02833882
Pitting in the bottom ring groove. DO NOT USE AGAIN

The ring groove gauge can be used on all pistons to inspect the grooves for the keystone ring. This gauge is recommended over former methods of checking ring groove wear because of increased tool accuracy. This gauge works on both one and two-piece pistons. Refer to Table 5 for the correct gauge part number.

Illustration 146	g01275836

Gauge is aligned with the center of the piston and the gauge has no side play.

Use the piston again.

Illustration 147	g01275838

Gauge does not slide far enough to align with the center of the piston.

Use the piston again.

Illustration 148	g01275839

Gauge is aligned with the center of piston and the gauge has side play. Any amount of side play is not acceptable.

Do not use the piston again.

Table 5 provides specifications for the piston and specifications for the piston ring.

Illustration 149	g01608173
Correct use of the ring groove gauge. The gauge should not go in the groove past the gauge line that is on the top of the gauge.

Follow this procedure to determine ring groove wear.

1. Ensure that the piston is clean.

2. Visually inspect the piston before proceeding further.

3. Select the proper Ring Groove Gauge from Table 5 and use the proper Ring Groove Gauge to measure the piston ring grooves.

4. Check the ring grooves in two locations at 90 degrees from the pin bores. If the gauge goes into a groove past the gauge line near the end of the gauge, do not use the piston again. Never use force to push the gauge into the groove.

5. The gauges have a gauge line across the width of the gauge for determining the maximum penetration of the gauge.

6. Reference Table 5 for the applicable specifications for piston ring grooves.

Inspect the Iron Band

Some one-piece pistons use an iron band for the top and intermediate ring grooves. The iron band is bonded to the piston during the manufacturing process. High potential exists for damage to the bonding for the iron band when the engine encounters cold starts of 10° C (50° F) or less. The result will be a loose iron band. If the iron band is loose or free, the piston cannot be used again. Identifying a loose iron band is difficult with a visual inspection.

Ultrasonic inspection is the only reliable method to determine if the iron band is correctly bonded to the piston body. The manufacturer uses the ultrasonic method to verify the retention of the iron band.

Illustration 150	g01276067
Use an ultrasonic flaw detection unit to determine if the band has separated.

Illustration 151	g01276068
Display of Ultrasonic Flaw Detection Unit

The display of the ultrasonic flaw detection unit will show if the piston can be used again. Illustration 152 and Illustration 153 show readings of bands. The readings can determine if the piston can be used again.

Illustration 152	g01276074
Correctly bonded bands should give a similar reading to the one above.

Use the piston again.

Illustration 153	g01276076
Bands that are incorrectly bonded will give a similar reading to the one above.

Do not use the piston again.

Visual inspection of the bond of the iron band requires looking for a gap or space between the edge of the iron band and the piston body.

Show/hide table

NOTICE
When the iron band bond is only visually inspected, there is a very high risk of reusing a piston with a loose iron band. This may result in a major failure.

Ring Lands

Illustration 154	g02833887
Slight scuffing/adhesive wear. A narrow patch of scuffing is acceptable for reuse. USE AGAIN

Illustration 155	g02833890
Slight scuffing/adhesive wear. This is a close up photo of Illustration 154. USE AGAIN

Illustration 156	g02835377
Slight scuffing/adhesive wear on the second land. This contact pattern is too wide for reuse of the piston. DO NOT USE AGAIN

Illustration 157	g02835379
Adhesive wear on ring lands. DO NOT USE AGAIN

Illustration 158	g02839518
Middle ring land polished smooth but no scratches. USE AGAIN

Illustration 159	g02835376
Slight pitting in the top ring land. USE AGAIN

Illustration 160	g06297226
The piston shows normal carbon scratches. The scratches are common on piston with offset pin bores. USE AGAIN

Illustration 161	g06297229
Example of light carbon scratches on the piston. USE AGAIN

Illustration 162	g06297232
The piston is displaying heavy carbon scratches in the top ring land. DO NOT USE AGAIN

Illustration 163	g06297239
The piston has light carbon scratches in the top ring land. USE AGAIN

Use the piston again after the raised areas are removed with a file and the piston is properly cleaned.

Illustration 164	g02835578
Slight pitting on the bottom land. USE AGAIN

Illustration 165	g02835576
Small nicks without raised material. USE AGAIN

Illustration 166	g02835382
Slight wear to bottom land with no raised metal and the machining marks still visible. USE AGAIN

Illustration 167	g02835586
Small ding to middle ring land that does not extend into the ring groove. This piston can be reused after salvage and inspection. USE AGAIN

Illustration 168	g02836556
Small ding on top of crown. USE AGAIN

Illustration 169	g02835579
Handling damage with slight raised material. This piston can be reused after salvage and inspection. USE AGAIN

Illustration 170	g02835582
Light handling damage with no raised material. USE AGAIN

Illustration 171	g02835584
Handling damage with raised material across the entire land. DO NOT USE AGAIN

Illustration 172	g02835588
Handling damage that runs across the lands. DO NOT USE AGAIN

Illustration 173	g02836657
Handling damage with raised material that extends into the ring groove. DO NOT USE AGAIN

Illustration 174	g02836716
Light handling damage. USE AGAIN

Illustration 175	g03586270
Ding in top ring land that has no raised material. USE AGAIN

Illustration 176	g02836719
Dent that is present across more than one land and also has raised material into the ring groove. DO NOT USE AGAIN

Illustration 177	g03586268
Small dent in bottom land with no raised material. USE AGAIN

Illustration 178	g02836721
Small dent in the top land with light raised material. This piston can be reused after salvage and inspection. USE AGAIN

Skirt

Illustration 179	g03586266
The horizontal marking is discoloration and does not affect the reusability of the piston. USE AGAIN

Illustration 180	g03586265
The horizontal markings are the result of the manufacturing process and are not a defect. USE AGAIN

Illustration 181	g01993079
Discoloration is due to the cleaning solution. USE AGAIN

Illustration 182	g02840281
A buffed and polished skirt that is ready for reuse. USE AGAIN

Illustration 183	g02870179
Polishing marks with the original machining marks still showing after polishing. USE AGAIN

Illustration 184	g02839818
Small dings with no raised metal. USE AGAIN

Illustration 185	g02870421
Slight ding on edge and side surface with no raised metal. USE AGAIN

Illustration 186	g02862484
Slight pitting. USE AGAIN

Illustration 187	g02839920
Slight pitting with no raised areas. USE AGAIN

Illustration 188	g02839819
Light scratches on the bottom of the skirt. USE AGAIN

Illustration 189	g02840168
Minor scratches in the bottom of skirt. USE AGAIN

Illustration 190	g02839919
Light handling damage with no raised material. USE AGAIN

Illustration 191	g02840167
Light scratches in the skirt. USE AGAIN

Illustration 192	g02840164
Steel piston with a scratch in the skirt that shows no raised material. USE AGAIN

Illustration 193	g02840257
This piston has been buffed and still shows a long deep scratch. DO NOT USE AGAIN

Illustration 194	g02840159
Deep horizontal scratch with raised material. DO NOT USE AGAIN

Illustration 195	g02840290
The scratches on this skirt are deeper than the machining marks and is quite large. DO NOT USE AGAIN

Illustration 196	g02840171
Large scratches deeper than machining marks and also with raised material. DO NOT USE AGAIN

Illustration 197	g02840387
Light scratch on the skirt. USE AGAIN

Illustration 198	g02840280
Scratch that still shows after polishing the skirt. DO NOT USE AGAIN

Illustration 199	g02840386
Light scuffing. USE AGAIN

Illustration 200	g02871536
Two dings in the skirt with light raised material. This piston can be reused after salvage and inspection. USE AGAIN

Illustration 201	g02840170
Deep gouges in the skirt. DO NOT USE AGAIN

Illustration 202	g02840237
Large gouge above the pin bore. DO NOT USE AGAIN

Illustration 203	g03585897

Damage on top surface of the skirt. This damage is at the joint between the skirt and the crown on two-piece pistons. No damage is allowed in this area. DO NOT USE AGAIN

Illustration 204	g02872467
Scuffing on the skirt with transferred material. DO NOT USE AGAIN

Illustration 205	g02871660
Scuffing on the skirt with transferred material. DO NOT USE AGAIN

Illustration 206	g02862798
Scuffing on the skirt with transferred material. DO NOT USE AGAIN

Illustration 207	g02840288
Severe scuffing due to seizure. DO NOT USE AGAIN

Illustration 208	g02864699
Severe scuffing due to seizure. DO NOT USE AGAIN

Illustration 209	g02864704
Severe scuffing due to seizure. DO NOT USE AGAIN

Note: No embedded material is allowed. Embedded material appears as dark hard specks in the skirt surface that can scratch the cylinder wall. Do not reuse any piston skirt that has embedded material.

Illustration 210	g01989435
Material is embedded into the surface. DO NOT USE AGAIN

Illustration 211	g03585901
Material is embedded into the surface. DO NOT USE AGAIN

Illustration 212	g03585902
Small amounts of embedded material are unacceptable. DO NOT USE AGAIN

Illustration 213	g01993234
This example shows heavy concentration of embedded particles. DO NOT USE AGAIN

Illustration 214	g01993235
A single large embedded particle is unacceptable, even if scratches are light. DO NOT USE AGAIN

Illustration 215	g01993236
Scratches are not deep and no embedded material is visible. USE AGAIN

Illustration 216	g01993237
Scratches are not deep and no embedded material is visible. USE AGAIN

Structure

Illustration 217	g02872659
Clean underside of piston. No discoloration or any other defects seen. USE AGAIN

Illustration 218	g02872661
Clean underside of piston. No discoloration or any other defects seen. USE AGAIN

Illustration 219	g02872665
Slight Pitting. USE AGAIN

Illustration 220	g02872677
Slight Pitting. USE AGAIN

Illustration 221	g02872679
Heavy Pitting. DO NOT USE AGAIN

Graphite Coated Pistons

Note: If a piston has severe scoring, material transfer, embedded material, or other obvious damage the piston should not be used again.

Illustration 222	g03398643

If the lower cover plates of the cooling gallery are found to be loose, the piston cannot be used again. Great care should be taken to inspect the inside of the cooling gallery for debris. The use of a borescope may aid in inspecting the gallery.

Illustration 223	g02863420
Mild wear of graphite coating with no scratches. USE AGAIN

Illustration 224	g02862678
Mild wear to graphite with scratch not penetrating the graphite coating. USE AGAIN

Illustration 225	g02863421
Mild wear to graphite coating with no scratches. Slight polishing to upper skirt area. USE AGAIN

Note: Do not use the piston again if the loss of coating on the skirt exceeds half the area of the skirt. The piston should not be reused if the wear is from hard contact.

Illustration 226	g02863439
No deep scratches but over half of graphite coating is worn away. DO NOT USE AGAIN

Illustration 227	g02862679
Polishing should not go out to the edge of the skirt. DO NOT USE AGAIN

Illustration 228	g02863418
Minor scratches/coating wear/handling damage. USE AGAIN

Illustration 229	g02862736
Scratches with over half of the graphite coating worn. DO NOT USE AGAIN

Illustration 230	g02862756
Over half of the graphite coating is worn. DO NOT USE AGAIN

Illustration 231	g02862796
Over half of the graphite coating is worn. DO NOT USE AGAIN

Illustration 232	g02864698
Over half of the graphite coating is worn. DO NOT USE AGAIN

Illustration 233	g02877646
Debonding of the graphite coating. DO NOT USE AGAIN

Illustration 234	g02864702
Debonding of the graphite coating. DO NOT USE AGAIN

Cracks in the Piston

Small cracks around the heat plug are normal. To measure these cracks, use a 34 gauge wire that has a diameter of 0.15 mm (0.006 inch) as a gauge. A 6V-2196 Microscope and 6V-7894 Microlite can also be used.

Illustration 235	g06297500
If necessary, use a 6V-2196 Microscope and 6V-7894 Microlite to measure the size of the cracks around the heat plug.

Illustration 236	g06297503
View the cracks through the eyepiece of the 6V-2196 Microscope. This crack is wider than 0.15 mm (0.006 inch).

Illustration 237	g06297509
Small cracks that are less than 0.15 mm (0.006 inch) wide around the heat plug. USE AGAIN

Illustration 238	g06297510
The arrows show cracks that are wider than 0.15 mm (0.006 inch). DO NOT USE AGAIN

Illustration 239	g06297514
Large cracks connected to each other. DO NOT USE AGAIN

Illustration 240	g06297522
The crack goes across the area between the relief for the valves. DO NOT USE AGAIN

Illustration 241	g06297530
Cracks in the crater that are not wider than 0.15 mm (0.006 inch). USE AGAIN

Note: Direct injection aluminum pistons have a sharp edge at the edge of the crater bowl to ensure good engine performance for emissions and fuel economy. Fine cracks can begin at this sharp edge due to thermal fatigue and mechanical fatigue. Although some fine cracking may be normal, larger cracks can be a sign of severe engine load factor. The pistons with crater cracks that are less than 6.00 mm (0.236 inch) long may be reused. The piston can be reused if the cracks are on the edge of the crater rim of the piston. The cracks in the piston should not be within 30 degrees of the centerline of the piston pin bore.

Illustration 242	g02877359
Cracks that are less than 6.00 mm (0.236 inch) long are allowed within the shaded area. (A) 30 degrees (B) 6.00 mm (0.236 inch)

Illustration 243	g06297532
The cracks are in the crater area of an aluminum direct injection piston. Measure the length and angle of the crack in relation to the pin bore. Use the piston again if the crack is less than 6.00 mm (0.236 inch) long and the crack is not within 30 degrees of the pin bore. This crack is over 6.00 mm (0.236 inch). DO NOT USE AGAIN

Illustration 244	g06297536
The crack in the piston is outside of the allowable area for cracks. DO NOT USE AGAIN

Illustration 245	g06297541
A crack in the top land of the piston. DO NOT USE AGAIN

Illustration 246	g06297546
The crack is in the ring land of the piston. DO NOT USE AGAIN

Illustration 247	g01199333
The piston is showing heavy damage to the skirt. A piston with cracks in any area of the skirt make the piston unusable. DO NOT USE AGAIN

Note: Illustration 248,249, and 250 are the same piston. There is wear on the outside of the skirt but closer inspection shows a crack on the inside of the skirt.

Illustration 248	g03390700

Illustration 249	g03390704

Illustration 250	g03390736

No cracks are permitted. DO NOT USE AGAIN

Illustration 251	g01201914
The piston has a crack in the web area. There is also damage near the pin bore of the piston. DO NOT USE AGAIN

Damage from Improper Handling

Illustration 252	g02840163
Top skirt damage. This piston can be reused after salvage operation and reinspect piston. USE AGAIN

Illustration 253	g02776937
Small ding in crown. This piston can be reused after salvage operation and inspection. USE AGAIN

Illustration 254	g02817941
Small dent in very edge of crown. USE AGAIN

Illustration 255	g02776936
Small dent in crown. This piston can be reused after salvage operation and inspection. USE AGAIN

Illustration 256	g02783251
Large dent in very edge of crown. DO NOT USE AGAIN

Illustration 257	g02783259
Small dent in very edge of crown. USE AGAIN

Illustration 258	g02817940
Small dent in very edge of crown. USE AGAIN

Illustration 259	g02821959
Nick in the pin bore. DO NOT USE AGAIN

Reconditioning Procedure

There are several methods for reconditioning minor damage to the piston crown and the piston skirt. Use the method for cleaning that is least aggressive during the process for reconditioning of the piston.

A depression results when a part is scratched, nicked, or dented. The scratch, the nick, or the dent can also result in an area that is raised.

Illustration 260	g02882814
Carefully remove the raised metal area that is caused by nicks, dents, and scratches. Illustration 249 shows examples of the various types of damage to the piston. In order for the piston to be reused, the piston must be cleaned and the area of metal that is raised must be removed from the surface. (A) Scratch (B) Raised Metal

The raised areas of the piston can be removed by several methods. The most common methods of removing raised metal are a file, a polishing wheel, or a Scotch-Brite abrasive disc. The file is the most aggressive method for removing raised material. The file is recommended for small areas on the surface for material that has been raised more than 0.20 mm (0.008 inch). Use caution to ensure that only the raised material is removed. Be sure that no indentations are left behind from the reconditioning procedure.

The polishing wheel and the Scotch-Brite abrasive disc are used to remove small scratches in larger areas. The piston skirt is made from aluminum. To reduce the risk of damage to the piston, manual buffing is preferred to a polishing wheel to remove scratches and imperfections. Illustration 182 and Illustration 183 show an example of a skirt that was buffed with a Scotch-Brite abrasive disc.

Piston Pins that are Reusable

A piston pin can usually be used again if the following specifications are met.

• The piston pin does not have visible signs of scratches, grooves, or nicks.

• The piston pin does not have indication of smearing or metal transfer.

• The surface texture is within the specification of 0.125 µm (5.0000 µinch). Refer to "Procedure to Check Surface Texture" within this document.

• The piston pin does not have a wear step that is larger than 0.005 mm (0.0002 inch). Refer to the section "Wear Step" within this document.

• The piston pin is within the diameter specifications listed in Table 12.

Note: Discoloration on the piston pin has no effect on the performance.

Visual Inspection

A through visual inspection is the first step in determining the reusability of a piston pin. Inspect the pin for nicks, dings, cracks, grooves, and overall abuse. The following are some examples of light wear, however the piston pin is still reusable.

Illustration 261	g01248172
Reuse the Pin

The piston pin is smooth. Grooves or wear steps cannot be felt on this pin.

Note: The dark horizontal lines on the piston pin are dark spots in the picture. These lines will not be found on piston pins that are checked in the field. Most of the photos in this guideline have these black lines in various forms. The black lines should be ignored.

Illustration 262	g01248175
Reuse the Pin

The surface of the piston pin is smooth.

Discoloration

Hot engine oil can discolor the piston pin through normal operation. Normally discoloration alone does not affect the pins hardness or heat treatment. Discoloration alone is not a reason to discard a piston pin. The following section shows some examples of common discoloration that can occur and still reuse the piston pin.

Illustration 263	g01248377
Reuse the Pin

The piston pin is discolored from hot engine oil.

Illustration 264	g01248382
Reuse the Pin

The piston pin is discolored from hot engine oil. Use the pin again if the surface is smooth and scratches cannot be felt.

Illustration 265	g01248386
Reuse the Pin

The piston pin has been polished but the stains remain. No pits of rust exist.

Illustration 266	g01248476
Reuse the Pin

The piston pin is discolored on the surface.

Illustration 267	g01248486
Reuse the Pin

The piston pin is discolored from the engine oil.

Illustration 268	g01248497
Reuse the Pin

The piston pin is discolored from the engine oil. Use the pin again if the surface is smooth and scratches cannot be felt with a fingernail.

Illustration 269	g01248514
Reuse the Pin

The piston pin is discolored. The discoloration may remain on the pin. Use the pin again if the surface is smooth and the pin meets the requirements for the surface texture.

Illustration 270	g01248548
Reuse the Pin

The piston pin is discolored.

Piston Pins that are not Reusable

A piston pin cannot usually be used again if the following specifications are met.

• The piston pin has distinct signs of scratches, grooves, or nicks.

• The piston pin has indication of smearing or metal transfer.

• The surface texture is beyond specifications. Refer to Table 12 within this document.

• The piston pin has wear steps that are larger than specifications. Refer to the section "Wear Step" within this document.

• The piston pin is not within the diameter specifications listed in Table 12.

Visual Inspection

A through visual inspection is the first step in determining the reusability of a piston pin. Inspect the pin barrel, end and chamfer area for nicks, dings, cracks, grooves, and overall abuse. The following are some visual indicators that would render a piston pin unusable.

Illustration 271	g06297607
Do Not Reuse the Pin

The piston pin has a scratch or a groove on the surface. Scratches or grooves are not acceptable.

Illustration 272	g06297611
Do Not Reuse the Pin

The piston pin has a nick on the end of the pin. Nicks are not acceptable in any area of the piston pin.

Illustration 273	g06297614
Do Not Reuse the Pin

The piston pin has damage from smearing.

Illustration 274	g06297616
Do Not Reuse the Pin

The piston pin shows indications of aluminum transfer.

Illustration 275	g06297618
Do Not Reuse the Pin

The piston pin has a rough surface texture. When the surface texture is more than 0.125 µm (5.0000 µinch), the surface texture is considered rough and unacceptable.

Illustration 276	g06246567
Do Not Reuse the Pin

The piston pin shows wear of the coating on the pin. Do not reuse piston pins with the coating that is worn off.

Handling Damage

Care must be taken during the disassembly process. The following are some examples of damage that was created in handling the piston pin after disassembly.

Illustration 277	g01249363
Do Not Reuse the Pin

The piston pin has damage from handling on both ends.

Illustration 278	g01249380
Do Not Reuse the Pin

The piston pin has nicks near the area for the rod eye bushing.

Illustration 279	g01259849
Do Not Reuse the Pin

The piston pin has a small nick (A) near the area for the rod eye bushing and a stain (B). The stain is acceptable, but the nicks are unacceptable.

Rust Pitting

Rust will occasionally occur on the piston pin. When the rust is deep and begins to eat into the metal with a pit, then the pin would not be reusable. The following are some examples of piston pins that had surface rust, were cleaned and polished, and the rust pits remained.

Illustration 280	g01249407
Do Not Reuse the Pin

The piston pin has been polished to remove the stains, but the pits of rust remain on the piston pin.

Illustration 281	g01249410
Do Not Reuse the Pin

The piston pin has been polished to remove the discoloration, but pits of rust remain on the piston pin.

Illustration 282	g01249537
Do Not Reuse the Pin

The piston pin still has pits of rust after being polished.

Illustration 283	g01249550
Do Not Reuse the Pin

The piston pin has one large pit of rust and several small pits of rust near the area of wear for the rod eye bushing.

Illustration 284	g01249608
Do Not Reuse the Pin

The piston pin has a damaged area that looks like a stain. However, light pitting can be seen by using 8S-2257 Eye Loupe As.

Illustration 285	g01249612
Do Not Reuse the Pin

The piston pin has pits of rust in the area for the rod eye bushing.

Illustration 286	g01249677
Do Not Reuse the Pin

The piston pin has pits of rust that are still present after polishing.

Illustration 287	g01259854

The piston pin has pits of rust (C) after being polished.

Note: If the pits of rust are removed and the stains (B) remain, then the piston pin can be reused.

Illustration 288	g01259859
Do Not Reuse the Pin

The piston pin has pits of rust (C) that are present after polishing. Some stains (B) can appear to be pits of rust without close examination.

Wear Step

A wear step is formed as the piston runs in the engine. If a piston pin has wear steps that can be felt with a fingernail or measured beyond the specification, then the piston pin should not be reused. This section details how to measure a wear step in a piston pin.

Illustration 289	g06297629
Detail of an unacceptable wear step on a pin. Do Not Reuse the Pin (A) Wear step (B) Height of wear step

The wear step (A) can be felt with a fingernail. The height of the wear step (B) measures larger than 0.005 mm (0.0002 inch).

Illustration 290	g01249727
Excessive wear step. The wear step can be felt after polishing. Do Not Reuse the Pin

Illustration 291	g03443017
Do Not Reuse the Pin (A) Wear step (C) Pitting

The wear step (A) can be felt with a fingernail after polishing. Pitting (C) also makes the piston pin unusable.

Barrel Shaped Pins and Wear Steps

Some piston pins have a barrel shape near the ends of the pin (Illustration 292). This barrel shape can be mistaken for a wear step. Table 12 shows which piston pins have barrel shaped ends.

Illustration 292	g06297631
Detail of the barrel shape found on certain piston pins.

The height of the lip of barrel shaped pins is shown in Illustration 292. This lip in the pin can often be confused for a wear step, check Table 12 to see which pins are barrel shaped, and use good judgment when looking for a wear step.

Procedure to Measure Wear Steps

Illustration 293	g01249940

The piston pins can be checked for wear steps by hand. Refer to Illustration 293. If a wear step can be felt, the piston pin must be inspected more carefully. If a wear step can be felt and the wear step is more than 0.005 mm (0.0002 inch), then the pin is unacceptable.

Illustration 294	g01249947
An example of excessive wear steps on a piston pin.

To be acceptable for reuse, a wear step must be no larger than 0.005 mm (0.0002 inch).Pins with wear steps larger than 0.005 mm (0.0002 inch) cannot be reused. Measuring the wear step is possible with a V-block, a 3P-1568 Dial Indicator, a 6V-6167 Contact Point, and parts from a 8S-2328 Dial Indicator. Refer to Illustration 295 and Illustration 296.

Note: The back of the 3P-1568 Dial Indicator must be replaced with a back that has a vertical center lug. Refer to Illustration 296.

Illustration 295	g06297634

Illustration 296	g01249958
3P-1568 Dial Indicator with a back that has a vertical lug (A) and a 6V-6167 Contact Point (B)

Reusing Pin Plugs

Illustration 297	g01250434

Piston plugs can be reused if there are no signs of cracking, pitting, or scratches. This applies to all surfaces. Carefully check the fillet for cracking. Refer to Illustration 297.

Illustration 298	g01250529

Any wear on the plug must be evenly distributed around the top of the plug. Refer to Illustration 298. Normal wear will appear as a polished surface and no material will be removed. If the top of the plug shows signs of wear on the material, do not reuse the plug.

Show/hide table

NOTICE
If the plug or pin assembly is dropped, do not use it again. Dropping can cause impact loading which can cause a crack in the plug. The crack may not be visible during inspection. These cracks can then cause the parts to fail which will result in engine damage.

Piston Plug Assembly

When assembling the piston plug, take note of the following special assembly instructions.

Show/hide table

Illustration 299	g03441396

1. Apply Loctite Hysol 9434 epoxy in a continuous bead where indicated in 299 on each pin plug.

2. Insert the plug into the wrist pin.

3. Do not allow any visible adhesive to remain on the outside of the plug after assembly.

4. Allow five days to cure at room temperature.

Retaining Rings

The retaining rings for piston pins cannot be reused once the engine has been run. A retaining ring must always be replaced with a new ring after being removed from a piston.

Procedure for Measurement of Pistons and Pistons Pins

Checking Ring Gap

Recommendations state replacement of the piston rings whenever the piston is removed. However, the piston rings may be reused only if the following stringent criteria are met:

• The engine must have operated with the original piston less than 8,000 hours.

• There must be no visual defects on the piston ring.

• Reuse the piston ring with the same liner or a new liner.

Specifications of Pistons

Illustration 300	g06297678
Section view of piston showing pin of the ring groove gage

Table 5

Specifications of Pistons
Part Number of Piston			Pin Bore Diameter	Top Ring Groove
One Piece	Two-Piece			Straight or Tapered	Width of Straight Groove	Ring Groove Gauge	Pin for Tapered Ring Groove
	Crown	Skirt					(B)	(A)
2W-4831 2W-8410 2W-8411 2W-8412 2W-8414 2W-8415 7C-1146 7C-2553 7C-3858 7W-3846 7W-3847 7W-8111 9L-7737 9L-7827 9L-7828 9Y-1219 9Y-4187 9L-7737 9L-7827 9L-7828	N/A	N/A	Ø 38.118 ± 0.005 mm (1.5007 ± 0.0002 inch)	S	3.276 ± 0.013 mm (0.1290 ± 0.0005 inch)	N/A	N/A	N/A
4P-2654 4P-2655	N/A	N/A	Ø 38.128 ± 0.005 mm (1.5011 ± 0.0002 inch)	S	3.230 ± 0.010 mm (0.1272 ± 0.0004 inch)	N/A	N/A	N/A
4P-2990 9Y-7452 105-1710 107-7563 115-4124	N/A	N/A	Ø 40.005 ± 0.005 mm (1.5750 ± 0.0002 inch)	T	N/A	4C-8164	Ø 2.540 mm (0.1000 inch)	Ø 102.250 ± 0.076 mm (4.0256 ± 0.0030 inch)
4P-7187	N/A	N/A	Ø 50.815 ± 0.005 mm (2.0006 ± 0.0002 inch)	S	2.525 ± 0.010 mm (0.0994 ± 0.0004 inch)	N/A	N/A	N/A
4P-8996 107-1704 112-4585 127-5723 136-6007 160-7992 160-7994	N/A	N/A	Ø 50.815 ± 0.005 mm (2.0006 ± 0.0002 inch)	S	3.864 ± 0.010 mm (0.1521 ± 0.0004 inch)	N/A	N/A	N/A
6I-1144 7E-1298 7C-5668 101-4495	N/A	N/A	Ø 40.031 ± 0.007 mm (1.5760 ± 0.0003 inch)	T	N/A	4C-8164	Ø 2.540 mm (0.1000 inch)	Ø 102.250 ± 0.076 mm (4.0256 ± 0.0030 inch)
6I-4609 7E-7600 101-4140 133-9375 192-3896 197-3765 212-7596 280-3213 342-9847 486-0883 495-5305	N/A	N/A	Ø 70.003 ± 0.005 mm (2.7560 ± 0.0002 inch)	S	3.630 ± 0.010 mm (0.1429 ± 0.0004 inch)	N/A	N/A	N/A
7C-0473	N/A	N/A	Ø 50.815 ± 0.008 mm (2.0006 ± 0.0003 inch)	T	N/A	325-8422	Ø 3.300 mm (0.1299 inch)	Ø 134.639 ± 0.097 mm (5.3007 ± 0.0038 inch)
7C-2431 9Y-2100 9Y-4124	N/A	N/A	Ø 70.003 ± 0.005 mm (2.7560 ± 0.00020 inch)	T	N/A	9U-7360	Ø 3.500 mm (0.1378 inch)	Ø 168.630 ± 0.097 mm (6.6390 ± 0.0038 inch)
7C-3496	N/A	N/A	Ø 50.808 ± 0.004 mm (2.0003 ± 0.0002 inch)	T	N/A	325-8423	Ø 3.300 mm (0.1299 inch)	Ø 134.820 ± 0.100 mm (5.3079 ± 0.0039 inch)
7E-0292	N/A	N/A	Ø 55.021 ± 0.004 mm (2.1662 ± 0.0002 inch)	T	N/A	4C-8169	Ø 3.300 mm (0.1299 inch)	Ø 134.341 ± 0.097 mm (5.2890 ± 0.0038 inch)
7E-0305 7E-0539 7E-8656 7E-8700 7E-8885 160-1131	N/A	N/A	Ø 50.814 ± 0.004 mm (2.0005 ± 0.0002 inch)	T	N/A	4C-8169	Ø 3.302 mm (0.1300 inch)	Ø 134.341 ± 0.097 mm (5.2890 ± 0.0038 inch)
7E-1298 9Y-7452	N/A	N/A	Ø 40.005 ± 0.005 mm (1.5750 ± 0.0002 inch)	T	N/A	4C-8164	Ø 2.540 mm (0.1000 inch)	Ø 102.250 ± 0.076 mm (4.0256 ± 0.0030 inch)
7E-3888 7E-8335	N/A	N/A	Ø 50.815 ± 0.005 mm (2.0006 ± 0.0002 inch)	S	2.527 ± 0.013 mm (0.0995 ± 0.0005 inch)	N/A	N/A	N/A
7E-4729 7E-9937 101-0812 118-2285	N/A	N/A	Ø 38.128 ± 0.005 mm (1.5011 ± 0.0002 inch)	T	N/A	4C-8166	Ø 2.540 mm (0.1000 inch)	Ø 111.087 ± 0.076 mm (4.3735 ± 0.0030 inch)
7N-3510 7N-3511	N/A	N/A	Ø 50.815 ± 0.008 mm (2.0006 ± 0.0003 inch)	T	N/A	N/A	Ø 2.540 mm (0.1000 inch)	Ø 133.932 ± 0.097 mm (5.2729 ± 0.0038 inch)
8L-5277	N/A	N/A	Ø 38.128 ± 0.005 mm (1.5011 ± 0.0002 inch)	S	3.233 ± 0.013 mm (0.1273 ± 0.0005 inch)	N/A	N/A	N/A
8N-3180 8N-3184	N/A	N/A	Ø 38.128 ± 0.005 mm (1.5011 ± 0.0002 inch)	S	3.233 ± 0.013 mm (0.1273 ± 0.0005 inch)	N/A	N/A	N/A
9N-5249	N/A	N/A	Ø 43.182 ± 0.005 mm (1.7001 ± 0.0002 inch)	S	3.233 ± 0.013 mm (0.1273 ± 0.0005 inch)	N/A	N/A	N/A
9N-5402				T	N/A	4C-8168	Ø 2.540 mm (0.1000 inch)	Ø 117.455 ± 0.097 mm (4.6242 ± 0.0038 inch)
9Y-3116	N/A	N/A	Ø 50.815 ± 0.008 mm (2.0006 ± 0.0003 inch)	T	N/A	4C-8169	Ø 3.302 mm (0.1300 inch)	Ø 134.341 ± 0.097 mm (5.2890 ± 0.0038 inch)
9Y-7212 9Y-9889 378-1441	N/A	N/A	Ø 50.815 ± 0.008 mm (2.0006 ± 0.0003 inch)	T	N/A	4C-8169	Ø 3.302 mm (0.1300 inch)	Ø 134.341 ± 0.097 mm (5.2890 ± 0.0038 inch)
100-7403	N/A	N/A	Ø 50.814 ± 0.004 mm (2.0005 ± 0.0002 inch)	T	N/A	4C-8169	Ø 3.302 mm (0.1300 inch)	Ø 134.341 ± 0.097 mm (5.2890 ± 0.0038 inch)
101-0016 117-5063	N/A	N/A	Ø 55.021 ± 0.004 mm (2.1662 ± 0.0002 inch)	T	N/A	4C-8169	Ø 3.300 mm (0.1299 inch)	Ø 134.341 ± 0.097 mm (5.2890 ± 0.0038 inch)
107-0984 107-8366 128-2952 128-3295 160-6600 200-7904 225-4284 234-4814 239-8506 346-2096 418-9359	N/A	N/A	Ø 30.005 ± 0.005 mm (1.1813 ± 0.0002 inch)	T	N/A	4C-8164	Ø 2.550 mm (0.1004 inch)	Ø 95.112 ± 0.210 mm (3.7445 ± 0.0082 inch)
107-3565 154-8087 165-4262 168-4531	N/A	N/A	Ø 43.118 ± 0.004 mm (1.6976 ± 0.0002 inch)	T	N/A	4C-8168	Ø 2.540 mm (0.1000 inch)	Ø 117.455 ± 0.097 mm (4.6242 ± 0.0038 inch)
129-0358 164-6560	N/A	N/A	Ø 43.188 ± 0.004 mm (1.7003 ± 0.0002 inch)	S	3.233 ± 0.013 mm (0.1273 ± 0.0005 inch)	N/A	N/A	N/A
136-9360	N/A	N/A	Ø 130.059 ± 0.009 mm (5.12042 ± 0.00035 inch)	S	Top Ring 6.175 ± 0.015 mm (0.24311 ± 0.00059 inch)	197-3710	N/A	N/A
					Center Ring 6.175 ± 0.015 mm (0.24311 ± 0.00059 inch)	197-3710	N/A	N/A
					Oil Control Ring 8.075 ± 0.015 mm (0.31791 ± 0.00059 inch)	N/A	N/A	N/A
144-0720	N/A	N/A	Ø 70.035 ± 0.005 mm (2.75728 ± 0.00020 inch)	T	N/A	9U-7360	Ø 3.500 mm (0.1378 inch)	Ø 168.630 ± 0.097 mm (6.6390 ± 0.0038 inch)
160-1131	N/A	N/A	Ø 50.814 ± 0.004 mm (2.0005 ± 0.0002 inch)	T	N/A	4C-8169	Ø 3.302 mm (0.1300 inch)	Ø 134.341 ± 0.097 mm (5.2890 ± 0.0038 inch)
165-4262 168-4531	N/A	N/A	Ø 43.188 ± 0.004 mm (1.7003 ± 0.0002 inch)	T	N/A	4C-8168	Ø 2.540 mm (0.1000 inch)	Ø 117.455 ± 0.097 mm (4.6242 ± 0.0038 inch)
172-3280 174-6102 174-6103	N/A	N/A	Ø 50.814 ± 0.004 mm (2.0005 ± 0.0002 inch)	T	N/A	4C-8169	Ø 3.302 mm (0.1300 inch)	Ø 134.341 ± 0.097 mm (5.2890 ± 0.0038 inch)
192-2208 192-2209 367-5183	N/A	N/A	Ø 50.858 ± 0.008 mm (2.0023 ± 0.0003 inch)	T	N/A	325-8423	Ø 3.300 mm (0.1299 inch)	Ø 134.820 ± 0.100 mm (5.3079 ± 0.0039 inch)
197-9340	N/A	N/A	Ø 40.012 ± 0.003 mm (1.5753 ± 0.0001 inch)	T	N/A	325-8420	Ø 3.162 mm (0.1245 inch)	Ø 109.660 ± 0.100 mm (4.3171 ± 0.0039 inch)
238-2729								Ø 109.810 ± 0.100 mm (4.3232 ± 0.0039 inch)
197-9381 197-9383 265-1111 267-2068 286-7208 322-0329 322-3146 322-3148 339-8174 339-8176 339-8177 342-6357 384-3698 388-2310 388-9353 388-9355 388-9356	N/A	N/A	Ø 53.250 ± 0.010 mm (2.0965 ± 0.0004 inch)	T	N/A	208-7632	Ø 3.500 mm (0.1378 inch)	Ø 128.530 ± 0.097 mm (5.0602 ± 0.0038 inch)
219-8102	N/A	N/A	Ø 60.093 ± 0.008 mm (2.3658 ± 0.0003 inch)	T	N/A	325-8418	Ø 2.54 mm (0.100 inch)	Ø 143.5 ± 0.1 mm (5.649 ± 0.0039 inch)
233-2431	N/A	N/A	Ø 69.864 mm (2.7505 inch) to 70.075 mm (2.7588 inch)	T	N/A	246-1176	Ø 3.500 mm (0.1378 inch)	Ø 168.350 ± 0.111 mm (6.6279 ± 0.0044 inch)
235-6257	N/A	N/A	Ø 60.093 ± 0.008 mm (2.3658 ± 0.0003 inch)	T	N/A	325-8419	Ø 2.540 mm (0.1000 inch)	Ø 143.500 ± 0.100 mm (5.6496 ± 0.0039 inch)
235-8098 239-7844 319-6715 329-4509 329-4510 329-4511	N/A	N/A	Ø 60.093 ± 0.008 mm (2.3658 ± 0.0003 inch)	T	N/A	N/A	Ø 3.300 mm (0.1299 inch)	Ø 142.250 ± 0.100 mm (5.6004 ± 0.0039 inch)
238-2698	N/A	N/A	Ø 40.012 ± 0.003 mm (1.5753 ± 0.0001 inch)	T	N/A	325-8420	Ø 3.162 mm (0.1245 inch)	Ø 109.610 ± 0.100 mm (4.3153 ± 0.0039 inch)
238-2713	N/A	N/A	Ø 53.220 ± 0.010 mm (2.0953 ± 0.0004 inch)	T	N/A	N/A	3.500 mm (0.1378 inch)	128.72 ± 0.097 mm (5.0677 ± 0.0038 inch)
238-2720	N/A	N/A	Ø 40.038 ± 0.010 mm (1.5763 ± 0.0004 inch)	T	N/A	325-8420	Ø 3.000 mm (0.1181 inch)	Ø 108.664 ± 0.080 mm (4.2781 ± 0.0031 inch)
247-6123 248-5516 252-0656 306-7460	N/A	N/A	Ø 60.093 ± 0.008 mm (2.3658 ± 0.0003 inch)	T	N/A	325-8420	Ø 3.300 mm (0.1299 inch)	Ø 134.820 ± 0.100 mm (5.3079 ± 0.0039 inch)
247-7791 247-7792	N/A	N/A	Ø 60.093 ± 0.008 mm (2.3658 ± 0.0003 inch)	T	N/A	325-8423	Ø 3.300 mm (0.1299 inch)	Ø 134.820 ± 0.110 mm (5.3079 ± 0.0043 inch)
262-7330	N/A	N/A	Ø 46.015 ± 0.003 mm (1.8116 ± 0.0001 inch)	T	N/A	325-8420	Ø 3.200 mm (0.1260 inch)	Ø 110.189 ± 0.075 mm (4.3381 ± 0.0030 inch)
262-7331 319-7886 357-0447 369-5326 396-1539 437-7099	N/A	N/A	Ø 50.013 ± 0.003 mm (1.9690 ± 0.0001 inch)	T	N/A	418-9826	Ø 3.270 mm (0.1287 inch)	Ø 115.845 ± 0.110 mm (4.5608 ± 0.0043 inch)
262-9288	N/A	N/A	Ø 40.012 ± 0.003 mm (1.5753 ± 0.0001 inch)	T	N/A	325-8420	Ø 3.200 mm (0.1260 inch)	Ø 110.189 ± 0.075 mm (4.3381 ± 0.0030 inch)
265-1313	N/A	N/A	Ø 53.220 ± 0.010 mm (2.0953 ± 0.0004 inch)	T	N/A	208-7632	Ø 3.500 mm (0.1378 inch)	Ø 128.530 ± 0.097 mm (5.0602 ± 0.0038 inch)
278-0274 299-5204 314-5005 314-5006 314-5007 348-5356 374-2082 374-2083 453-2335 481-5617	N/A	N/A	Ø 70.0705 ± 0.0075 mm (2.75868 ± 0.00030 inch)	T	N/A	246-1176	Ø 3.500 mm (0.1378 inch)	Ø 168.350 ± 0.111 mm (6.6279 ± 0.0044 inch)
278-0574	N/A	N/A	Ø 40.012 ± 0.003 mm (1.5753 ± 0.0001 inch)	T	N/A	325-8420	Ø 2.900 mm (0.1142 inch)	Ø 107.830 ± 0.080 mm (4.2453 ± 0.0031 inch)
280-7098 322-3149	N/A	N/A	Ø 53.260 ± 0.010 mm (2.0969 ± 0.0004 inch)	T	N/A	208-7632	Ø 3.500 mm (0.1378 inch)	Ø 128.530 ± 0.097 mm (5.0602 ± 0.0038 inch)
290-0017 378-0509	N/A	N/A	Ø 50.815 ± 0.008 mm (2.0006 ± 0.0003 inch)	T	N/A	4C-8169	Ø 3.302 mm (0.1300 inch)	Ø 134.341 ± 0.097 mm (5.2890 ± 0.0038 inch)
297-7750 297-7751 297-7752 297-7753	N/A	N/A	Ø 34.007 ± 0.005 mm (1.3389 ± 0.0002 inch)	T	N/A	4C-8164	Ø 3.000 mm (0.1181 inch)	Ø 102.336 ± 0.241 mm (4.0290 ± 0.0095 inch)
319-6716 319-6717 330-6090	N/A	N/A	Ø 60.093 ± 0.008 mm (2.3658 ± 0.0003 inch)	T	N/A	325-8425	Ø 3.300 mm (0.1299 inch)	Ø 142.250 ± 0.100 mm (5.6004 ± 0.0039 inch)
322-0329	N/A	N/A	Ø 53.25 ± 0.01 mm (2.09645 ± 0.00039 inch)	T	N/A	208-7632	Ø 3.500 mm (0.1378 inch)	Ø 128.530 ± 0.097 mm (5.0602 ± 0.0038 inch)
323-4017 323-4018 477-2237 477-2235	N/A	N/A	Ø 75.121 ± 0.008 mm (2.9575 ± 0.0003 inch)	S	Top Ring 3.6 ± 0.01 mm (0.142 ± 0.0004 inch)	510-5864	N/A	N/A
					Intermediate Ring 3.11 ± 0.01 mm (0.12244 ± 0.00039 inch)	327-8645	N/A	N/A
					Oil Control Ring 4.06 ± 0.01 mm (0.15984 ± 0.00039 inch)	327-8646	N/A	N/A
325-9492 330-7762 342-6359 346-6615 346-6616 346-6617 346-6618 347-3241 352-4981 356-4787 356-9946 376-7362 381-9249 381-9250 432-1858	N/A	N/A	Ø 60.095 ± 0.010 mm (2.3659 ± 0.0004 inch)	T	N/A	325-8423	Ø 3.400 mm (0.1339 inch)	Ø 135.6795 ± 0.1185 mm (5.34170 ± 0.00467 inch)
331-9822 339-3027 343-7301 348-5357 349-8473 369-1284 376-8090	N/A	N/A	Ø 70.0705 ± 0.0075 mm (2.75868 ± 0.00030 inch)	T	N/A	N/A	Ø 3.500 mm (0.1378 inch)	Ø 164.397 ± 0.111 mm (6.4723 ± 0.0044 inch)
338-3641	N/A	N/A	Ø 60.095 ± 0.005 mm (2.3659 ± 0.0002 inch)	T	N/A	N/A	Ø 3.8 mm (0.150 inch)	Ø 146.425 ± 0.125 mm (5.7647 ± 0.0050 inch)
346-2096 478-7472	N/A	N/A	Ø 70.003 ± 0.005 mm (2.7560 ± 0.0002 inch)	S	3.6 ± 0.01 mm (0.142 ± 0.0004 inch)	N/A	N/A	N/A
361-5742 361-5744 367-5160 375-8134 375-8261 394-3591	N/A	N/A	Ø 60.125 ± 0.005 mm (2.3671 ± 0.0002 inch)	T	N/A	325-8425	Ø 3.6 mm (0.1417 inch)	Ø 144.705 ± 0.125 mm (5.6970 ± 0.0049 inch)
362-9350 362-9351	N/A	N/A	Ø 60.125 ± 0.005 mm (2.3671 ± 0.0002 inch)	T	N/A	N/A	Ø 3.8 mm (0.150 inch)	Ø 146.425 ± 0.125 mm (5.7647 ± 0.0050 inch)
367-5181	N/A	N/A	Ø 60.095 ± 0.005 mm (2.3659 ± 0.0002 inch)	T	N/A	325-8425	Ø 3.6 mm (0.1417 inch)	Ø 144.705 ± 0.125 mm (5.6970 ± 0.0049 inch)
368-7815 368-7816 368-7817 368-7818 368-8179 372-4884 372-4970 396-0368	N/A	N/A	Ø 60.125 ± 0.005 mm (2.3671 ± 0.0002 inch)	T	N/A	325-8425	Ø 3.6 mm (0.1417 inch)	Ø 144.705 ± 0.125 mm (5.6970 ± 0.0049 inch)
384-2884	N/A	N/A	Ø 70.0705 ± 0.0075 mm (2.75868 ± 0.00030 inch)	S	3.630 ± 0.010 mm (0.1429 ± 0.0004 inch)	N/A	N/A	N/A
384-3698	N/A	N/A	Ø 53.250 ± 0.010 mm (2.0965 ± 0.0004 inch)	T	N/A	N/A	Ø 3.4 mm (0.1339 inch)	Ø 127.67 ± 0.097 mm (5.0263 ± 0.0038 inch)
385-1657	N/A	N/A	Ø 46.04 ± 0.01 mm (1.813 ± 0.0004 inch)	T	N/A	325-8421	Ø 3.300 mm (0.1299 inch)	Ø 113.059 ± 0.100 mm (4.4511 ± 0.0039 inch)
418-9359	N/A	N/A	Ø 70.0705 ± 0.0075 mm (2.7587 ± 0.0003 inch)	S/T	3.6 ± 0.01 mm (0.142 ± 0.0004 inch)	N/A	Ø 3.500 mm (0.1378 inch)	Ø 168.35 ± 0.111 mm (6.62794 ± 0.00437 inch)
444-6465	N/A	N/A	Ø 50.09 mm (1.9720 inch) to 50.11 mm (1.9728 inch)	T	N/A	N/A	Ø 3.2 mm (0.1260 inch)	Ø 115.247 ± 0.100 mm (4.5373 ± 0.0034 inch)
458-7308	N/A	N/A	Ø 70.071 ± 0.008 mm (2.7587 ± 0.0003 inch)	S	3.630 ± 0.010 mm (0.1429 ± 0.0004 inch)	N/A	N/A	N/A
N/A	4P-5852 133-7098 197-9358	238-2710	Ø 50.830 ± 0.008 mm (2.0012 ± 0.0003 inch)	T	N/A	4C-8165	Ø 3.500 mm (0.1378 inch)	Ø 123.530 ± 0.097 mm (4.8634 ± 0.0038 inch)
N/A	4P-8959 7C-7888 118-3517 150-2512 204-6114 204-6117 205-5807 205-5808 205-5809 240-4641 240-4642 240-4643 240-4644 240-4645	N/A	Ø 120.0605 ± 0.0205 mm (4.72678 ± 0.00081 inch)	S	Top Ring 5.16 ± 0.01 mm (0.20315 ± 0.00039 inch)	4C-3654	N/A	N/A
					Center Ring 5.16 ± 0.01 mm (0.20315 ± 0.00039 inch)	4C-3654	N/A	N/A
					Oil Control Ring 8.05 ± 0.01 mm (0.31693 ± 0.00039 inch)	1U-9029	N/A	N/A
N/A	6I-1210 6I-4248 105-1720 107-7545 107-7553 107-7852 115-4088 142-7307	238-2716	40.031 ± 0.007 mm (1.5760 ± 0.0003 inch)	T	N/A	4C-8164	Ø 2.540 mm (0.1000 inch)	Ø 102.250 ± 0.076 mm (4.0256 ± 0.0030 inch)
N/A	113-5999 123-4612 155-4336 173-0138 197-9314	163-0930	Ø 50.858 ± 0.008 mm (2.0023 ± 0.0003 inch)	T	N/A	325-8423	Ø 3.300 mm (0.1299 inch)	Ø 134.820 ± 0.100 mm (5.3079 ± 0.0039 inch)
N/A	113-6119 133-4983 133-5044 144-3444 150-4621 164-6556 165-4265 175-3671 197-9320 391-7837 393-8986393-8987 393-8988	238-2726	Ø 40.031 ± 0.007 mm (1.5760 ± 0.0003 inch)	T	N/A	186-0190	Ø 2.540 mm (0.1000 inch)	Ø 104.709 ± 0.040 mm (4.1224 ± 0.0016 inch)
N/A	114-6655 156-1704 157-1116 204-4131 204-4438 204-5282 290-2036 290-2037 359-1722	154-4318 156-5568 201-5389 204-5268 290-2038	Ø 120.0605 ± 0.0205 mm (4.72678 ± 0.00081 inch)	S	Top Ring 5.15 ± 0.01 mm (0.20276 ± 0.00039 inch)	4C-3654	N/A	N/A
					Center Ring 5.15 ± 0.01 mm (0.20276 ± 0.00039 inch)	4C-3654	N/A	N/A
					Oil Control Ring 8.05 ± 0.01 mm (0.31693 ± 0.00039 inch)	1U-9029	N/A	N/A
N/A	123-4612	163-0930	Ø 50.824 ± 0.004 mm (2.0009 ± 0.0002 inch)	T	N/A	325-8423	Ø 3.300 mm (0.1299 inch)	Ø 134.820 ± 0.100 mm (5.3079 ± 0.0039 inch)
	180-7352 221-2305	132-6663	Ø 55.047 ± 0.008 mm (2.1672 ± 0.0003 inch)
	7C-2888	128-2830
	125-8869 135-2837 138-1791 149-5566 168-4540	130-0241
N/A	128-5633 173-3952	128-5634 172-6773	Ø 120.0405 ± 0.0205 mm (4.72599 ± 0.00081 inch)	S	Top Ring 5.16 ± 0.01 mm (0.20315 ± 0.00039 inch)	4C-3654	N/A	N/A
					Center Ring 5.16 ± 0.01 mm (0.20315 ± 0.00039 inch)	4C-3654	N/A	N/A
					Third Ring 5.050 ± 0.010 mm (0.19882 ± 0.00039 inch)	1U-9030	N/A	N/A
					Oil Control Ring 8.05 ± 0.01 mm (0.31693 ± 0.00039 inch)	1U-9029	N/A	N/A
N/A	139-8500 139-8500 192-8810	284-6039	Ø 55.0505 ± 0.0055 mm (2.16734 ± 0.00022 inch)			208-7636	Ø 3.300 mm (0.1299 inch)	Ø 137.436 ± 0.100 mm (5.4109 ± 0.0039 inch)
	145-6700	130-0241	Ø 55.077 ± 0.008 mm (2.1684 ± 0.0003 inch)			325-8423		Ø 134.820 ± 0.100 mm (5.3079 ± 0.0039 inch)
N/A	144-2948 197-9328 197-9374	238-2712	Ø 53.190 ± 0.005 mm (2.0941 ± 0.0002 inch)	T	N/A	208-7632	Ø 3.500 mm (0.1378 inch)	Ø 128.530 ± 0.097 mm (5.0602 ± 0.0038 inch)
N/A	145-6700	130-0241	Ø 55.077 ± 0.008 mm (2.1684 ± 0.0003 inch)	T	N/A	325-8423	Ø 3.300 mm (0.1299 inch)	Ø 134.820 ± 0.100 mm (5.3079 ± 0.0039 inch)
N/A	172-0919 249-4512 279-6770	155-5271	Ø 70.0525 ± 0.0075 mm (2.75797 ± 0.00030 inch)	T	N/A	204-8041	4.100 mm (0.1614 inch)	169.494 ± 0.111 mm (6.6730 ± 0.0044 inch)
	230-9043	230-8095
N/A	180-7351 180-7352 221-2305 225-0115	132-6663	Ø 55.019 ± 0.045 mm (2.1661 ± 0.0018 inch)	T	N/A	325-8423	Ø 3.300 mm (0.1299 inch)	Ø 134.820 ± 0.100 mm (5.3079 ± 0.0039 inch)
N/A	197-9297	324-7380	Ø 46.04 ± 0.01 mm (1.81259 ± 0.00039 inch)	T	N/A	325-8417	Ø 2.540 mm (0.1000 inch)	Ø 110.340 ± 0.100 mm (4.3441 ± 0.0039 inch)
	197-9303 197-9345 197-9368 238-2701 265-1401 272-2312 385-1657					325-8421	Ø 3.300 mm (0.1299 inch)	Ø 113.059 ± 0.100 mm (4.4511 ± 0.0039 inch)
N/A	314-2694 436-9030	314-2695 436-9026	Ø 120.0375 ± 0.0225 mm (4.72588 ± 0.00089 inch)	S	Top Ring 6.185 ± 0.015 mm (0.24350 ± 0.00059 inch)	197-3710	N/A	N/A
					Center Ring 6.185 ± 0.015 mm (0.24350 ± 0.00059 inch)	197-3710	N/A	N/A
					Oil Control Ring 8.050 ± 0.010 mm (0.31693 ± 0.00039 inch)	N/A	N/A	N/A
N/A	393-8990	N/A	Ø 55.030 ± 0.005 mm (2.1665 ± 0.0002 inch)	T	N/A	208-7636	Ø 3.300 mm (0.1299 inch)	Ø 137.436 ± 0.100 mm (5.4109 ± 0.0039 inch)

Two-Piece Pistons in 3054 and 3056

Table 6

Piston Pin Bore Specifications
Description	Dimension
Diameter of the Bore for the Piston Pin (Naturally Aspirated Engines)	34.928 mm (1.3751 inch) to 34.934 mm (1.375 inch)
Diameter of the Bore for the Piston Pin (Turbocharged Engines)	38.103 mm (1.5001 inch) to 38.109 mm (1.5003 inch)

If the gap is larger than the dimensions shown, the ring and/or the bore may be worn.

Table 7

Top Ring Gap Specifications (Turbocharged Engines)
Description	Dimension
Shape of groove for top ring Shape of top ring	Tapered Wedge
Gap of top ring	0.35 mm (0.0138 inch) to 0.80 mm (0.0315 inch)
Gap of top ring with internal step	0.35 mm (0.0138 inch) to 0.70 mm (0.0275 inch)
Top Ring Gap Specifications (Naturally Aspirated Engines)
Width of groove in piston for top ring	2.57 mm (0.101 inch) to 2.59 mm (0.102 inch)
Clearance between groove and top ring (new piston)	0.08 mm (0.003 inch) to 0.11 mm (0.004 inch)
Gap of top ring (early engines)	0.40 mm (0.016 inch) to 0.85 mm (0.033 inch)
Gap of top ring (later engines)	0.28 mm (0.011 inch) to 0.63 mm (0.025 inch)

Note: Install the word "TOP" toward the top of the piston. New top rings have a red or blue identification mark, which must be on the left of the ring gap when the top ring is installed on an upright piston.

Table 8

Intermediate Ring Gap Specifications (Turbocharged Engines)
Description	Dimension
Width of groove in piston for intermediate ring	2.56 mm (0.100 inch) to 2.58 mm (0.102 inch)
Clearance between the groove and the intermediate ring	0.07 mm (0.003 inch) to 0.11 mm (0.004 inch)
Gap of intermediate Ring	0.30 mm (0.011 inch) to 0.76 mm (0.030 inch)
Gap of intermediate ring with outside step	0.40 mm (0.016 inch) to 0.85 mm (0.033 inch)
Thickness of the intermediate ring	2.48 mm (0.097 inch) to 2.49 mm (0.098 inch)
Intermediate Ring Gap Specifications (Naturally Aspirated Engines)
Width of groove in piston for intermediate ring	2.55 mm (0.100 inch) to 2.57 mm (0.101 inch)
Clearance between the groove and the intermediate ring	0.06 mm (0.002 inch) to 0.09 mm (0.003 inch)
Gap of intermediate Ring Early Engines	0.30 mm (0.011 inch) to 0.76 mm (0.030 inch)
Gap of intermediate Ring Later Engines	0.40 mm (0.016 inch) to 0.85 mm (0.033 inch)

Note: Install the word "Top" toward the top of the piston. New intermediate rings have a green identification mark, which must be on the left of the ring gap when the intermediate ring is installed on an upright piston.

Table 9

Oil Control Ring Specifications (Turbocharged Engines)
Description	Dimension
Width of groove in piston for oil control ring	4.04 mm (0.159 inch) to 4.06 mm (0.159 inch)
Clearance between groove and oil control ring	0.05 mm (0.002 inch) to 0.08 mm (0.003 inch)
Gap of oil control ring	0.38 mm (0.015 inch) to 0.84 mm (0.033 inch)
Thickness of oil control ring	3.98 mm (0.156 inch) to 3.99 mm (0.157 inch)
Oil Control Ring Specifications (Naturally Aspirated Engines)
Width of groove in piston for oil control ring	4.03 mm (0.159 inch) to 4.06 mm (0.160 inch)
Clearance between groove and oil control ring	0.04 mm (0.002 inch) to 0.08 mm (0.003 inch)
Gap of oil control ring	0.38 mm (0.015 inch) to 0.84 mm (0.033 inch)
Thickness of oil control ring	3.98 mm (0.156 inch) to 3.99 mm (0.157 inch)

Piston Height

Illustration 301	g06177287

3054 & 3056

The piston height above the top face of the cylinder block is controlled by different grades of height of the piston. Identification of the height grade is by the letter that is stamped on the top of each piston. The difference between each grade of height is 0.045 mm (0.0018 inch).

Table 10

Height Grades of the Piston
Letter on top of the Piston	Height Dimension	Latest Equivalent Grade
A(1)	70.334 mm (2.7690 inch)	G
B(1)	70.289 mm (2.7672 inch)	H
C(1)	70.244 mm (2.7655 inch)	J
D(1)	70.199 mm (2.7637 inch)	K
E(1)	70.154 mm (2.7619 inch)	L
F	70.391 mm (2.7712 inch)	N/A
G	70.345 mm (2.7694 inch)	N/A
H	70.299 mm (2.7676 inch)	N/A
J	70.253 mm (2.7658 inch)	N/A
K	70.207 mm (2.7640 inch)	N/A
L	70.161 mm (2.7622 inch)	N/A

(1)	Earlier Engines

Illustration 302	g02465117
Piston height above top face of cylinder block Quadram piston 0.14 mm (0.006 inch) to 0.36 mm (0.014 inch)

Illustration 303	g02465140
Piston height above top face of cylinder block Fastram pistons 0.38 mm (0.015 inch) to 0.50 mm (0.0197 inch)

C175

When new pistons are being installed, new pistons must have the same height of compression.

Table 11

Height of Piston
Part Number of Piston	Height of Compression	Distance (K) from the Centerline of Pin Bore to the Top of the Piston
323-4017	Standard	120.8 ± 0.1 mm (4.756 ± 0.004 inch)
323-4018
477-2237
477-2235		121.0 ± 0.1 mm (4.764 ± 0.004 inch)

Piston Pin Measuring Locations

Straight Pin Locations

Straight piston pin diameter and roughness are measured in at least three places where the bushing has contacted the pin. Within the distance (A) from each end and the middle of the pin (B). Distance (A) on straight pins is determined by visually identifying where the piston pin bushing has contacted the pin. Refer to Table 12 for the minimum reuse diameter of piston pin.

Illustration 304	g06297639
(A) Measurement area of contact from piston pin bushing. (B) Measurement area of contact from piston rod bushing.

Tapered Pin Locations

Tapered Pin diameter and roughness are measured in at least three places. At least the distance (A) away from each end and at the middle of the pin (B). Refer to Table 12 for distance (A) and minimum reuse diameter of piston pin.

Illustration 305	g06297688
(A) Measurement of taper. (B) Measurement area of contact from piston rod bushing.

Barrel Shaped Pin Locations

Barrel Shaped Pin diameter and roughness is measured in at least three places. At the barrel radius peak, the distance (A) away from each end and at the middle of the pin. Refer to Table 12 for distance (A) and minimum reuse diameter of piston pin.

Illustration 306	g06297684
(A) Measurement from end of pin to peak of barrel. (B) Measurement area of contact from piston rod bushing.

Procedure to Check Surface Texture

Always check the surface texture of piston pins with adequate tooling. Do not reuse the piston pin if the surface texture is too rough. Refer to Table 12 for the surface texture specifications.

Piston Pin Specifications

Use the following guide for measuring the specifications of the piston pin.

Table 12

Specifications for Piston Pins
Piston Pin	Length (A)	Minimum Diameter for Reuse	Diameter of a New Piston Pin	Wear Step	Surface Texture (Ra)	Shape of Piston Pin
1M-6101 7N-9806	N/A	Ø 50.780 mm (1.9992 inch)	Ø 50.795 ± 0.005 mm (1.9998 ± 0.0002 inch)	0.005 mm (0.0002 inch)	0.125 µm (4.9212 µinch)	Straight
524-7988	6.1 mm (0.24016 inch)
4W-7403	N/A	Ø 69.942 mm (2.7536 inch)	Ø 69.957 ± 0.005 mm (2.7542 ± 0.0002 inch)	0.005 mm (0.0002 inch)	0.125 µm (4.9212 µinch)	Straight
4W-8484 138-8506	20.5 ± 2.5 mm (0.8071 ± 0.10 inch)	Ø 69.947 mm (2.7538 inch)	Ø 69.962 ± 0.005 mm (2.75440 ± 0.0002 inch)	0.005 mm (0.0002 inch)	0.125 µm (4.9212 µinch)	Barrel(1)
6I-2718	9.25 mm (0.364 inch)	Ø 50.780 mm (1.9992 inch)	Ø 50.795 ± 0.005 mm (1.9998 ± 0.0002 inch)	0.005 mm (0.0002 inch)	0.125 µm (4.9212 µinch)	Tapered
7C-0115 7C-3901	9.25 mm (0.364 inch)	Ø 39.985 mm (1.5742 inch)	Ø 40.000 ± 0.005 mm (1.57480 ± 0.0002 inch)	0.005 mm (0.0002 inch)	0.125 µm (4.9212 µinch)	Tapered
524-7980 524-7982	4.8 mm (0.18898 inch)
7C-1412	N/A	Ø 119.988 mm (4.7239 inch)	Ø 119.994 ± 0.006 mm (4.7242 ± 0.0002 inch)	0.005 mm (0.0002 inch)	0.125 µm (4.9212 µinch)	Straight
7C-8610 138-8507	N/A	Ø 69.957 mm (2.7542 inch)	Ø 69.962 ± 0.005 mm (2.75440 ± 0.0002 inch)	0.005 mm (0.0002 inch)	0.125 µm (4.9212 µinch)	Straight
7E-1749 168-7246	9.25 mm (0.364 inch)	Ø 54.985 mm (2.1648 inch)	Ø 55.000 ± 0.005 mm (2.1654 ± 0.0002 inch)	0.005 mm (0.0002 inch)	0.125 µm (4.9212 µinch)	Tapered
524-5613	6.6 mm (0.25984 inch)
7N-2393	N/A	Ø 69.950 mm (2.7539 inch)	Ø 69.965 ± 0.005 mm (2.7545 ± 0.0002 inch)	0.005 mm (0.0002 inch)	0.125 µm (4.9212 µinch)	Straight
7N-9803 9L-9889	N/A	Ø 38.082 mm (1.4993 inch)	Ø 38.097 ± 0.005 mm (1.4999 ± 0.0002 inch)	0.005 mm (0.0002 inch)	0.125 µm (4.9212 µinch)	Straight
7N-9804	9.25 mm (0.364 inch)	Ø 38.093 mm (1.4997 inch)	Ø 38.108 mm (1.5003 inch)	0.005 mm (0.0002 inch)	0.125 µm (4.9212 µinch)	Tapered
524-7984	4.6 mm (0.18110 inch)
7N-9805	9.25 mm (0.364 inch)	Ø 43.160 mm (1.6992 inch)	Ø 43.175 mm (1.6998 inch)	0.005 mm (0.0002 inch)	0.125 µm (4.9212 µinch)	Tapered
524-7986	5.2 mm (0.20472 inch)
7N-9807 7W-9710 8N-1608	9.25 mm (0.364 inch)	Ø 50.780 mm (1.9992 inch)	Ø 50.795 ± 0.005 mm (1.9998 ± 0.0002 inch)	0.005 mm (0.0002 inch)	0.125 µm (4.9212 µinch)	Tapered
524-5564 524-7990	6.1 mm (0.24016 inch)
8L-3443	N/A	Ø 50.780 mm (1.9992 inch)	Ø 50.795 ± 0.005 mm (1.9998 ± 0.0002 inch)	0.005 mm (0.0002 inch)	0.125 µm (4.9212 µinch)	Straight
8M-6487	N/A	Ø 43.160 mm (1.6992 inch)	Ø 43.175 mm (1.6998 inch)	0.005 mm (0.0002 inch)	0.125 µm (4.9212 µinch)	Straight
9H-4016	N/A	Ø 38.093 mm (1.4997 inch)	Ø 38.1076 ± 0.005 mm (1.5003 ± 0.0002 inch)	0.005 mm (0.0002 inch)	0.125 µm (4.9212 µinch)	Straight
094-7134	N/A	Ø 33.985 mm (1.3380 inch)	Ø 34.000 ± 0.005 mm (1.3385 ± 0.0002 inch)	0.005 mm (0.0002 inch)	N/A	Straight
101-3210	N/A	Ø 39.985 mm (1.5742 inch)	Ø 40.000 ± 0.005 mm (1.57480 ± 0.0002 inch)	0.005 mm (0.0002 inch)	0.125 µm (4.9212 µinch)	Straight
102-9796	9.25 mm (0.364 inch)	Ø 54.985 mm (2.1648 inch)	Ø 55.000 ± 0.005 mm (2.1654 ± 0.0002 inch)	0.005 mm (0.0002 inch)	0.125 µm (4.9212 µinch)	Tapered
524-7819	6.6 mm (0.25984 inch)
103-9679 234-4815	N/A	Ø 29.985 mm (1.1805 inch)	Ø 30.000 ± 0.005 mm (1.1811 ± 0.0002 inch)	0.005 mm (0.0002 inch)	N/A	Straight
138-8508	N/A	Ø 69.947 mm (2.7538 inch)	Ø 69.962 ± 0.005 mm (2.75440 ± 0.0002 inch)	0.005 mm (0.0002 inch)	0.125 µm (4.9212 µinch)	Straight
141-6063	N/A	Ø 129.929 mm (5.1153 inch)	Ø 129.944 ± 0.006 mm (5.1159 ± 0.0002 inch)	0.005 mm (0.0002 inch)	0.125 µm (4.9212 µinch)	Straight
153-5540	N/A	Ø 20.985 mm (0.8262 inch)	Ø 21.000 ± 0.002 mm (0.8268 ± 0.0001 inch)	0.005 mm (0.0002 inch)	N/A	N/A
154-0873	N/A	Ø 27.985 mm (1.1018 inch)	Ø 28.000 ± 0.004 mm (1.1024 ± 0.0002 inch)	0.005 mm (0.0002 inch)	N/A	N/A
161-8417	9.25 mm (0.364 inch)	Ø 50.755 mm (1.9982 inch)	Ø 50.770 mm (1.9988 inch)	0.005 mm (0.0002 inch)	0.125 µm (4.9212 µinch)	Tapered
524-7841	6.1 mm (0.24016 inch)
164-6555	9.25 mm (0.364 inch)	Ø 39.978 mm (1.5739 inch)	Ø 39.993 ± 0.005 mm (1.5745 ± 0.0002 inch)	0.005 mm (0.0002 inch)	N/A	Tapered
524-7845	4.8 mm (0.18898 inch)
166-3648	9.25 mm (0.364 inch)	Ø 45.985 mm (1.8104 inch)	Ø 46.000 ± 0.005 mm (1.8110 ± 0.0002 inch)	0.005 mm (0.0002 inch)	0.125 µm (4.9212 µinch)	Tapered
524-5611	5.5 mm (0.21654 inch)
168-7224	9.25 mm (0.364 inch)	Ø 39.978 mm (1.5739 inch)	Ø 39.993 ± 0.005 mm (1.5745 ± 0.0002 inch)	0.005 mm (0.0002 inch)	0.125 µm (4.9212 µinch)	Tapered
524-7848	4.8 mm (0.18898 inch)
168-7226	9.25 mm (0.364 inch)	Ø 39.978 mm (1.5739 inch)	Ø 39.993 ± 0.005 mm (1.5745 ± 0.0002 inch)	0.005 mm (0.0002 inch)	0.125 µm (4.9212 µinch)	Tapered
524-0480	4.8 mm (0.18898 inch)
168-7276	9.25 mm (0.364 inch)	Ø 50.780 mm (1.9992 inch)	Ø 50.795 ± 0.005 mm (1.9998 ± 0.0002 inch)	0.005 mm (0.0002 inch)	0.125 µm (4.9212 µinch)	Tapered
524-6484	6.1 mm (0.24016 inch)
168-7296	9.25 mm (0.364 inch)	Ø 53.155 mm (2.0927 inch)	Ø 53.170 ± 0.005 mm (2.0933 ± 0.0002 inch)	0.005 mm (0.0002 inch)	0.125 µm (4.9212 µinch)	Tapered
524-6469	6.4 mm (0.25197 inch)
173-0148	9.25 mm (0.364 inch)	Ø 50.780 mm (1.9992 inch)	Ø 50.795 ± 0.005 mm (1.9998 ± 0.0002 inch)	0.005 mm (0.0002 inch)	0.125 µm (4.9212 µinch)	Tapered
524-7118	6.1 mm (0.24016 inch)
180-7350	9.25 mm (0.364 inch)	Ø 59.960 mm (2.3606 inch)	Ø 59.975 ± 0.005 mm (2.3612 ± 0.0002 inch)	0.005 mm (0.0002 inch)	0.125 µm (4.9212 µinch)	Tapered
524-5565	7.2 mm (0.28346 inch)
197-0560	15 mm (0.591 inch)	Ø 69.947 mm (2.7538 inch)	Ø 69.962 ± 0.005 mm (2.75440 ± 0.0002 inch)	0.005 mm (0.0002 inch)	0.125 µm (4.9212 µinch)	Straight
197-9291	9.25 mm (0.364 inch)	Ø 59.930 mm (2.3594 inch)	Ø 59.945 ± 0.005 mm (2.3600 ± 0.0002 inch)	0.005 mm (0.0002 inch)	0.125 µm (4.9212 µinch)	Tapered
524-7850	7.2 mm (0.28346 inch)
197-9327	9.25 mm (0.364 inch)	Ø 53.140 mm (2.0921 inch)	Ø 53.155 ± 0.005 mm (2.0927 ± 0.0002 inch)	0.005 mm (0.0002 inch)	0.125 µm (4.9212 µinch)	Tapered
524-6478	6.4 mm (0.25197 inch)
197-9371	9.25 mm (0.364 inch)	Ø 39.973 mm (1.5737 inch)	Ø 39.988 ± 0.005 mm (1.5743 ± 0.0002 inch)	0.005 mm (0.0002 inch)	0.125 µm (4.9212 µinch)	Tapered
524-6492	4.8 mm (0.18898 inch)
215-5829	9.25 mm (0.364 inch)	Ø 54.960 mm (2.1638 inch)	Ø 54.975 mm (2.1644 inch)	0.005 mm (0.0002 inch)	0.125 µm (4.9212 µinch)	Tapered
238-2731	9.25 mm (0.364 inch)	Ø 49.985 mm (1.9679 inch)	Ø 50.000 ± 0.005 mm (1.9685 ± 0.0002 inch)	0.005 mm (0.0002 inch)	0.125 µm (4.9212 µinch)	Tapered
524-5566	6.0 mm (0.23622 inch)
238-2735	9.25 mm (0.364 inch)	Ø 45.985 mm (1.8104 inch)	Ø 46.000 ± 0.005 mm (1.8110 ± 0.0002 inch)	0.005 mm (0.0002 inch)	0.125 µm (4.9212 µinch)	Tapered
524-7881	5.5 mm (0.21654 inch)
239-6051	N/A	Ø 74.985 mm (2.952 inch)	Ø 75.000 ± 0.005 mm (2.95275 ± 0.00020 inch)	0.005 mm (0.0002 inch)	0.125 µm (4.9212 µinch)	Straight
263-8955	15 mm (0.591 inch)	Ø 69.915 mm (2.7526 inch)	Ø 69.930 ± 0.005 mm (2.7531 ± 0.0002 inch)	0.005 mm (0.0002 inch)	0.125 µm (4.9212 µinch)	Straight
272-0961	9.25 mm (0.364 inch)	Ø 54.960 mm (2.1638 inch)	Ø 59.975 ± 0.005 mm (2.36122 ± 0.00020 inch)	0.005 mm (0.0002 inch)	0.125 µm (4.9212 µinch)	Tapered
524-7884	6.6 mm (0.25984 inch)
302-3451	23.00 mm (0.906 inch)	Ø 69.915 mm (2.7526 inch)	Ø 69.930 ± 0.005 mm (2.7531 ± 0.0002 inch)	0.005 mm (0.0002 inch)	0.125 µm (4.9212 µinch)	Tapered
384-0401	9.25 mm (0.364 inch)	Ø 49.970 mm (1.9673 inch)	Ø 49.985 ± 0.005 mm (1.9679 ± 0.0002 inch)	0.005 mm (0.0002 inch)	0.125 µm (4.9212 µinch)	Tapered
384-0401	6.0 mm (0.23622 inch)
392-4608	109.85 ± 0.25 mm (4.32479 ± 0.00984 inch)	Ø 74.985 mm (2.952 inch)	Ø 75.000 ± 0.005 mm (2.95275 ± 0.00020 inch)	0.005 mm (0.0002 inch)	0.125 µm (4.9212 µinch)	Straight
469-1989	9.25 mm (0.364 inch)	Ø 54.960 mm (2.1638 inch)	Ø 59.975 ± 0.005 mm (2.36122 ± 0.00020 inch)	0.005 mm (0.0002 inch)	0.08 µm (3.1496 µinch)	Tapered
524-5565	7.2 mm (0.28346 inch)				0.09 µm (3.5433 µinch)

(1)	Lip Height of barrel shaped piston pinch: .02 ± 0.005 mm (0.00079 ± 0.00020 inch)

Procedure for Assembly

Note: Caterpillar does not recommend disassembly and subsequent assembly of the 3618 piston or gas piston. Disassembly and subsequent assembly should only apply to the diesel engine that has three and four piston rings.

Note: Provide a clean environment for assembly and torquing, and use a nonmetallic surface for storing and handling to avoid scratching the surfaces that are matching.

Note: Ensure that the piston components are cleaned prior to assembly.

Show/hide table

NOTICE
Keep all parts clean from contaminants Contaminants may cause rapid wear and shorten component life

Pistons with a Single Bolt and Three Rings

Show/hide table

Illustration 307	g06321542

1. Place the skirt back on the crown. The alignment pin (1) should be in the hole (2) in the skirt. The alignment pin should not be in an oil passage.
   Show/hide table

   Illustration 308	g06321546
   (3) Washer (4) Spacer (5) Washer (6) Bolt

2. Place the washer and the spacer in the skirt. Make sure that they have the proper orientation.

3. Lubricate the bolt threads and the area under the bolt head with Molykote-Paste G-n Plus.

4. Tighten the bolt to a torque of 160.0 N·m (118.01 lb ft).

5. Loosen the bolt and then tighten the bolt to a torque of 40.0 N·m (29.50 lb ft).

6. Place the 342-6241 Piston Gauge on the washer around the bolt and place the 0° mark on the skirt and measure back to the line on the bolt. If this measurement is greater than 60°, then the piston is reusable for a second life.

7. If the measurement is NOT greater than 60°, torque the bolt an additional 90°.

Piston Crown to Piston Skirt for the Piston that has Four Rings

The following is a set of step-by-step instructions for reassembly of the piston. Reference the applicable Tables that accompany the steps of the procedure for the specifications for torquing the hardware and torque and then turn specifications.

Show/hide table

Illustration 309	g06321549

1. Place the piston crown upside-down on a flat surface. Clean the stud holes (2) in the crown and the stud threads with a degreaser that is alcohol. Before beginning the assembly, ensure that the bolt hole is clean and ensure that the bolt hole is dry. Assemble the studs (1) into the crown with no lubrication, and torque the studs to 40 N·m (29.5 lb ft).

2. The new O-ring seal should be coated with P-80 Assembly Lubricant or another grease that is free from acid for ease of assembly. Make sure that all the studs, the nuts, and the contact surface of the spacers are clean and dry. Minor scratches and minor nicks may be reworked at the discretion of the technician.

   Note: Remove all the plugs that were used during the cleaning of the piston.

3. Install the skirt onto the crown. Use a brush and apply a thin coat of 6V-4876 Molybdenum Paste to the stud threads and to the contact surface of the hex nut.

4. To properly seat the crown to the skirt, torque all four nuts in a cross pattern to 80 N·m (59.0 lb ft).

5. Loosen all four nuts and recheck the torque for the studs. The torque should be 40 N·m (29.5 lb ft). Measure the distance from the end of the skirt to the end of the studs and record the value.
   Show/hide table

   Illustration 310	g06321554

6. Tighten the nuts until the nuts are finger tight. Measure the “inner” gap and record the “inner” gap between the steel crown and the aluminum skirt at four points around the piston. The “inner” gap should be measured with a feeler gauge in two locations that are parallel to the pin bore and the “inner” gap should be measured with a feeler gauge in two locations that are perpendicular to the pin bore. The measurement locations should be zero degrees, 90 degrees, 180 degrees, and 270 degrees. The “inner” gap should not exceed 0.15 mm (0.006 inch). If the gap exceeds this measurement the piston will not have the probability of meeting expected operating hours.

7. Torque each nut in a cross pattern to 15 N·m (11.1 lb ft).

8. Use the SPX/OTC J36660 tool that is to torque and turn. Turn the nuts in a cross pattern to 90 degrees.

   Note: There will be some clearance in the tooling that will accompany the twisting and the torque reaction that occurs during the turning portion of torquing of the nuts and this will result in the nut that will have turned a number of degrees less than the indication on the keypad. To determine the amount of lost turn, relax the force on the greaser bar and then pull back until all the clearance and the torque reaction is removed. Note the reading on the keypad and offset the 90 degrees of turn by the amount of torque reaction. Normally, the clearance and the torque reaction will be approximately 3 to 5 degrees that is dependent on the hand tools that are used.

9. Assembly Check

   The retaining nuts should not turn when 55 N·m (40.6 lb ft) of torque is applied.

   Note: The torque specification of the Assembly Check which is step 9 is not a replacement for the assembly procedure.

10. Remeasure the distance from the end of the skirt to the end of the studs and record the value.

11. Calculate the stretch of the stud and record the stretch of the stud. The distance is equal to 0.30 ± 0.05 mm (0.012 ± 0.002 inch). The stretch of the stud equals the measured distance with the nuts that are loose minus the measured distance that is referred to in the previous statement. Ifthe stretch of the stud varies from the average stretch of the stud that is over 0.05 mm (0.002 inch) then the following steps must be repeated. Loosen the nuts. Remeasure the distance. Tighten the nuts. Recalculate the stretch on the stud. If the variation of the stretch of the stud still exceeds 0.05 mm (0.002 inch) then replace all the pieces for retention. The pieces for retention include the studs, the nuts, and the spacers.

12. Mark each skirt on the bottom of the rim or mark each boss that is part of the skirt to show the date that the piston was reconditioned. Refer to Reuse and Salvage Guideline, SEBF8187, "Standardized Parts Marking Procedures" for additional information.

Installation of the Piston Rings

Show/hide table

NOTICE
Do not install the piston rings without the use of the piston ring expander. Piston ring breakage and piston damage may result if the piston ring expander is not used.

Use the following steps to install the piston rings for all engine models.

Note: Use the appropriate Ring Expander Group to install the oil ring first. Refer to Table 3 for the correct tool. The oil ring is the bottom piston ring on the piston. A spring is on the inner diameter of the grooved oil ring. The middle of the spring is marked with a white band. Orient the ends of the spring to 180 degrees opposite side of the ring gap. The white band on the spring will be visible through the ring gap.

1. Grip the oil ring and grip the spring in the inner diameter of the ring. Separate the two ends of the spring until the oil ring is expanded enough to be installed over the piston. After the oil ring is over the bottom groove in the piston, release the spring and allow the oil ring to contract into the groove. Make sure that the white band on the spring is visible through the ring gap.

2. Use the appropriate Ring Expander Group to install the second compression ring. The second compression ring is the middle piston ring on the piston. Install the compression ring with the side marked “UP 2” toward the top of the piston. Install the compression ring in the middle groove of the piston. Orient the ring gap to 120 degrees away from the oil ring gap.

   Note: Pistons with four piston rings have two Center piston rings. Use the Ring Expander Group to install the third compression ring with the side marked “UP 3” toward the top of the piston. The ring end gap must be 120 degrees from the adjacent ring end gap. Use the Ring Expander Group to install the second compression ring with the side marked “UP 2” toward the top of the piston. The ring end gap must be 120 degrees from the adjacent ring end gap.

3. Use the Ring Expander Group to install the first compression ring. The first compression ring is the top piston ring on the piston (3). Install the compression ring with the side marked “UP 1” toward the top of the piston. Orient the ring gap to 120 degrees away from the adjacent ring gap.

Crack Detection Methods

Show/hide table

NOTICE
Regardless of which crack detection method is used, it is important that the instructions furnished with the detection equipment are followed closely when checking any component. Failure to do so may cause inaccurate results or may cause injury to the operator and/or surroundings.

Crack detection methods or Non-Destructive Testing (NDT) are utilized for examining components for cracks without damaging the component. Visual inspection (VT), Liquid Penetrant Testing (PT), Magnetic Particle Inspection (MT), Ultrasonic Testing (UT), Radiographic Testing (RT) and Eddy-Current Testing (ET) are recommended methods. There may be more than one acceptable crack detection method for the inspection of a given part, though the liquid penetrant is the most versatile. For example, the liquid penetrant method can be used when inspecting smooth machined components such as shafts, gear teeth, and splines, but using the Wet Magnetic Particle Inspection is more accurate. Refer to Table 13 for advantages and disadvantages and Table 14 for standards and requirements for these NDT methods.

Table 13

Crack Inspection Method Advantages vs. Disadvantages
Inspection Method	Advantages	Disadvantages
Visual Surface Inspection (VT)	- Least expensive - Detects most damaging defects - Immediate results - Minimum part preparation	- Limited to surface-only defects - Requires inspectors to have broad knowledge of welding and fabrication in addition to non-destructive testing
Liquid Penetrant (PT)	- Inexpensive - Minimal training - Portable - Works on nonmagnetic material	- Least sensitive - Detects surface cracks only - Rough or porous surfaces interfere with test
Dry Magnetic Particle (MT)	- Portable - Fast/Immediate Results - Detects surface and subsurface discontinuities	- Works on magnetic material only - Less sensitive than Wet Magnetic Particle
Wet Magnetic Particle (MT)	- More sensitive than Liquid Penetrant - Detects subsurface as much as 0.13 mm (0.005 inch)	- Requires Power for Light - Works on magnetic parts only - Liquid composition and agitation must be monitored
Ultrasonic Testing (UT)	- Most sensitive - Detects deep material defects - Immediate results - Wide range of materials and thickness can be inspected	- Most expensive - Requires operator training and certification - Surface must be accessible to probe
Eddy-Current Testing (ET)	- Surface and near surface flaws detectable -Moderate speed/Immediate results -Sensitive too small discontinuities	- Difficult to interpret - Only for metals -Rough surfaces interfere with test - Surface must be accessible to probe
Radiographic Testing (RT)	-Detects surface and internal flaws - Minimum part preparation - Can inspect hidden areas	- Not for porous materials - Radiation protection needed - Defect able to be detected is limited to 2% of thickness

Table 14

Applicable Crack Detection Standards
Inspection Method	Standard	Acceptance Criteria	Required Personnel Qualifications
Visual Surface Inspection (VT)	EN-ISO 5817 AWS D1.1	EN-ISO 5817 - Level B AWS D1.1 - Table 6.1	EN-ISO 9712 - Level 2 ANSI-ASNT SNT-TC-1A Level 2
Liquid Penetrant Testing (PT)	EN-ISO 3452 ASTM E165	EN-ISO 23277 AWS - D1.1	EN-ISO 9712 - Level 2 ANSI-ASNT SNT-TC-1A Level 2
Magnetic Particle Testing (MT)	EN-ISO 17638 ASTM E709	EN-ISO 23278 - Level 1 AWS D1.1 - Table 6.1	EN-ISO 9712 - Level 2 ANSI-ASNT SNT-TC-1A Level 2
Ultrasonic Testing (UT)	EN-ISO 17640 - Level B AWS D1.1	EN-ISO 11666 Technique 2 - Level 2 AWS D1.1 - Class A - Table 6.3	EN-ISO 9712 - Level 2 ANSI-ASNT SNT-TC-1A Level 2
Eddy-Current Testing (ET)	EN-ISO 15549 ASTM E426	EN-ISO 20807	EN-ISO 9712 - Level 2 ANSI-ASNT SNT-TC-1A Level 2
Radiographic Testing (RT)	EN-ISO 5579 ASTM E94	EN-ISO 10657-1	EN-ISO 9712 - Level 2 ANSI-ASNT SNT-TC-1A Level 2

Visual Surface Inspection (VT)

Illustration 311	g06085008
Example of Visual Inspection Tools (A) Flashlight or adequate light source (B) Magnifying eye loupe (C) Tape measure or other measuring device (D) Inspection mirror (E) Weld size inspection gauges

Components and welds that are to be inspected using PT, MT, or UT shall first be subject to Visual Surface Inspection (VT). Visual Inspection is often the most cost-effective inspection method and requires little equipment as seen in Illustration 311. It is suggested that at a minimum personnel performing Visual Inspection are either trained to a company standard or have sufficient experience and knowledge with regard to the components being inspected. It is also suggested that personnel performing visual inspections take some type of eyesight test regularly.

Liquid Penetrant Testing (PT)

Show/hide table

Personal injury can result from improper handling of chemicals. Make sure you use all the necessary protective equipment required to do the job. Make sure that you read and understand all directions and hazards described on the labels and material safety data sheet of any chemical that is used. Observe all safety precautions recommended by the chemical manufacturer for handling, storage, and disposal of chemicals.

Materials and Equipment Required

Refer to Tooling and Equipment Table 3 for part numbers.

• Cleaner: Removes dirt before dye application and dissolves the penetrant making possible to wipe the surface clean.

• Penetrant: This solution is highly visible, and will seep into openings at the surface of a part with capillary action.

• Developer: Provides a blotting action, bringing the penetrant out of the discontinuities and providing a contrasting background to increase the visibility of the penetrant indications.

• Wire Brush: Removes dirt and paint.

• Cloth or Wipes: Use with cleaner and for other miscellaneous uses.

Procedure

Show/hide table

Illustration 312	g06107074
Typical example of pre-cleaning area.

1. Preclean inspection area. Spray on cleaner / remover to loosen any scale, dirt, or any oil. Wipe the area to inspect with a solvent dampened cloth to remove remaining dirt and allow the area to dry. If there is visible crack remove paint using paint remover or wire brush.
   Show/hide table

   Illustration 313	g06107081
   Typical example of applying penetrant.

2. Apply penetrant by spraying to the entire area to be examined. Allow 10 to 15 minutes for penetrant to soak. After the penetrant has been allowed to soak, remove the excess penetrant with clean, dry wipe.
   Show/hide table

   Illustration 314	g06107088
   Typical example of removing excess penetrant oil.

3. The last traces of penetrant should be removed with the cleaner solvent dampened cloth or wipe. Allow the area to dry thoroughly.
   Show/hide table

   Illustration 315	g06107094
   Typical example of applying developer.

4. Before using Developer, ensure that it is mixed thoroughly by shaking can. Holding can approximately 203.20 - 304.80 mm (8.00 - 12.00 inch) away from part, apply an even, thin layer of developer over the area being inspected. A few thin layers are a better application method than one thick layer.
   Show/hide table

   Illustration 316	g06084042
   Typical example of cracks found during a liquid penetrant testing.

5. Allow the developer to dry completely for 10–15 minutes before inspecting for cracks. Defects will show as red lines in white developer background, refer to Illustration 316. Clean the area of application of the developer with solvent cleaner.

Dry Magnetic Particle Testing (MT)

Materials and Equipment Required

Refer to Tooling and Equipment Table 3 for part numbers.

Illustration 317	g06085930
(A) Indications shown by magnetic particle testing. (B) Typical electromagnetic yoke. (C) Dry powder bulb.

1. Dry magnetic powder shall be of high permeability and low retentively and of suitable sizes and shapes to produce magnetic particle indications. The powder shall be of a color that will provide adequate contrast with the background of the surface being inspected.

2. Dry magnetic particles shall be stored in suitable containers to resist contamination such as moisture, grease, oil, non-magnetic particles such as sand, and excessive heat. Contaminants will manifest in the form of particle color change and particle agglomeration. The degree of contamination will determine further use of the powder.

3. Dry magnetic powder shall be tested in accordance with ASTM E709 Section 18 (Evaluation of System Performance/Sensitivity) when not performing.

4. Equipment should include a "U" shaped electromagnetic yoke made from highly permeable magnetic material, which has a coil wound around the yoke. This coil carries a magnetizing current to impose a localized longitudinal magnetic field into the part. The magnetizing force of the yoke is related to the electromagnetic strength and can be tested by determining the lifting power of a steel plate. The yoke shall have a lifting force of at least 4.5 kg (10 lbs).

5. Check dry powder blower routinely to ensure that the spray is a light, uniform, dust-like coating of the dry magnetic particles. Blower should also have sufficient force to remove excess particles without disturbing those particles that are evidence of indications.

6. All equipment shall be inspected at a minimum of once a year or when accuracy is questionable.

Procedure

1. Ensure surface to be inspected is dry and free from oil, grease, sand, loose rust, mil scale, paint, and other contaminants.

2. Apply the magnetic field using the yoke against the faces and inside diameter of each bore.

3. Simultaneously apply the dry powder using the dry powder blower.

4. Remove excess powder by lightly blowing away the dry particles.

5. Continue around the entire circumference of each bore. Position the yoke twice in each area at 1.57 rad (90°) to ensure that multiple directions of the magnetic field are created.

6. Observe particles and note if any clusters of particles appear revealing an indication.

7. Record the size and shape of any discontinuities or indications found.

Wet Magnetic Particle Testing (MT)

Materials and Equipment

Refer to Tooling and Equipment Table 3 for part numbers.

Illustration 318	g06085937
(A) Indications shown by magnetic particle testing. (B) Typical electromagnetic yoke. (D) UV Lamp used in wet magnetic particle inspection process.

Illustration 319	g06003178
Pear Shaped Centrifuge Tube

1. Wet magnetic particles are fluorescent and are suspended in a vehicle in a given concentration that will allow application to the test surface by spraying.

2. Concentration:

   1. The concentration of the suspended magnetic particles shall be as specified by the manufacturer and be checked by settling volume measurements.

   2. Concentrations are determined by measuring the settling volume by using an ASTM pear shaped centrifuge tube with a 1 mL (0.034 oz) stem with 0.05 mL (0.0017 oz) 1.0 mL (0.034 oz) divisions, refer to Illustration 319. Before sampling, the suspension shall be thoroughly mixed to assure suspension of all particles, which could have settled. A 100 mL (3.40 oz) sample of the suspension shall be taken and allowed to settle for 30 minutes. The settling volume should be between 0.1 mL (0.0034 oz) and 0.25 mL (0.0085 oz) in a 100 mL (3.40 oz) sample.

   3. Wet magnetic particles may be suspended in a low viscosity oil or conditioned water.

   4. The oil shall have the following characteristics:

      • Low viscosity not to exceed 50 mSt (5.0 cSt) at any temperature at which the vehicle is to be used.

      • Low inherent fluorescence and be non-reactive.

   5. The conditioning agents used in the conditioned water shall have the following characteristics:

      • Impart good wetting characteristics and good dispersion.

      • Minimize foaming and be non-corrosive.

      • Low viscosity shall not exceed a maximum viscosity of 50 mSt (5.0 cSt) at 38° C (100° F).

      • Non-fluorescent, non-reactive, and odorless.

      • Alkalinity shall not exceed a pH of 10.5.

3. Equipment should include a "U" shaped electromagnetic yoke made from highly permeable magnetic material, which has a coil wound around the yoke. This coil carries a magnetizing current to impose a localized longitudinal magnetic field into the part. The magnetizing force of the yoke is related to the electromagnetic strength and can be tested by determining the lifting power of a steel plate. The yoke shall have a lifting force of at least 4.5 kg (10 lbs).

Procedure

1. Ensure surface to be inspected is dry and free from oil, grease, sand, loose rust, mil scale, paint, and any other contaminants.

2. Apply the magnetic field using the yoke against the surface in the area to be inspected.
   Show/hide table

   Illustration 320	g03536210

3. For case hardened and ground surfaces:

   • Due to the sensitivity required to locate the grinding cracks, inspection of case hardened and ground surfaces require that the yoke is applied so that the magnetic field is 1.57 rad (90°) to the expected direction of the indications. Also, due to the increased sensitivity resulting when the yoke is energized, the yoke is not moved until the evaluation is completed in the first direction. An AC yoke shall be used. See Illustration 320 for an example of yoke placement.

4. Visually inspect for indications of discontinuities using the proper illumination.

5. Record the size and shape of any discontinuities found.

Ultrasonic Testing (UT)

Note: Crack depth cannot be accurately determined by UT, only full depth cracking can be consistently determined. For cracks that are not full depth, an indication of a partial depth cracks can be detected by an experienced technician.

Show/hide table

NOTICE
All personnel involved in ultrasonic testing shall be qualified to Level 2 in accordance to standards stated in Table 14.

Refer to Tooling and Equipment Table 3 for part numbers.

1. Ultrasonic Testing (UT) is a method of Non-Destructive Testing (NDT) using short ultrasonic pulse waves (with frequencies from 0.1-15 MHz up to 50 MHz) to detect the thickness of the object. Ultrasonic testing consists of an ultrasound transducer connected to a diagnostic machine and passed over the object being inspected.

2. There are two methods of receiving the ultrasound waveform from the transducer: reflection and attenuation.

   1. Reflection - Ultrasonic pulses exit the transducer and travel throughout the thickness of the material. When the sound waves propagate into an object being tested, the waves return to the transducer when a discontinuity is discovered along the sonic path. These waves continue and reflect form the backsurface of the material to project the thickness of the material.

   2. Attenuation - A transmitter sends ultrasound through one surface, and a separate receiver detects the amount that has reached it on another surface after traveling through the medium. Any discontinuities or other conditions within the medium will reduce the amount of sound transmitted, revealing the presence of the imperfections.

Eddy-Current Testing (ET)

Show/hide table

NOTICE
All personnel involved in Eddy-Current Testing shall be qualified to Level 2 in accordance to standards stated in Table 14.

Illustration 321	g06090873
Eddy-Current Testing

Eddy-Current Testing (ET) is a Non-Destructive Testing (NDT) method in which eddy-current flow is induced in the test object. Changes in the flow caused by variations in the specimen are reflected in to a nearby coil or coils for subsequent analysis by suitable instrumentation and techniques. Major applications of eddy-current testing are surface inspection and tubing inspections.

Radiographic Testing (RT)

Note: CAUTION: This process is dangerous. Only qualified personnel and test equipment should be appointed to perform this type of testing.

Show/hide table

NOTICE
All personnel involved in radiographic testing shall be qualified to Level 2 in accordance to standards stated in Table 14.

Illustration 322	g06090892
Radiographic Testing

Radiographic Testing (RT) is a Non-Destructive Testing (NDT) method in which short wavelength of electromagnetic radiation is used to penetrate materials to find hidden discontinuities such as cracks. In radiographic testing, the test object is placed between the radiation source and the film, or x-ray detector. The electromagnetic radiation will penetrate the thickness of the test object and, when all the way through, will project onto the film any indications that have been in the path of the radiation waves.