3306 Cylinder Head To Block Joint Repair Procedure{1124, 1101, 1201} Caterpillar

Introduction

This Special Instruction contains the necessary procedures and information for the repair of a 3306 engine after a cylinder head gasket failure. Proper repair procedures will increase the longevity of a head to block joint repair. The omission of any of the steps from the procedure could reduce the useful service life of the new cylinder head gasket.

In addition to the steps outlined in this special instruction, correct calibration and operation of other components/systems should be verified. These can include:

* Ether Starting Aids

* Timing Advance

* Governor Rack/Torque Settings

* Water Pump Output/Thermostat Operation

* Radiator/Oil Cooler Flow - Winter Fronts

* Intake/Exhaust System Restriction Levels

These components affect the cylinder pressure and thermal stress to which the head gasket is subjected. Improper calibration and operation will adversely affect the life of the head to block joint repair.

NOTE: Refer to the service manual for operations not covered in this special instruction. Refer to the guidelines for reusable parts for other criteria on component reuse not covered in this publication.

Combustion Gas Leakage Tests

Coolant loss and aeration can be caused by reasons other than combustion gas leakage past the head gasket fire ring seal.

Air can enter the system by:

Filling the system improperly.

Allowing the coolant level to drop too low.

Improper coolant system maintenance.

Venting the system improperly.

Through a cracked air compressor head.

Any cooling system leakage points.

Combustion gases can enter the cooling system at:

The head to block joint.

An injector adapter/seal.

A cracked cylinder head.

A cracked cylinder liner flange.

Through a pitted cylinder liner.

One way to detect air or combustion gases entrance in the cooling system is to visually inspect the system's components.

The simplest is to check the coolant level. Significant coolant aeration is unlikely if the system is full and no coolant has recently been added. If it is low, there may have been an overflow discharge, a result of air or gases in the cooling system.

A more thorough procedure is to pressurize the system [75 to 103 kPa (11 to 15 psi)] and check for external leaks:

Hoses and lines.

Clamps and connections

Water pump seal.

Radiator cap.

Radiator core, header and tanks.

Gaskets and drain plugs.

All of these could be sources of leaks and should be repaired immediately.

A properly functioning radiator cap is crucial to sealing and maintaining the cooling system pressure. If the cap is not seated tightly in the filler neck or the pressure relief valve opens at a pressure that is too low, the system pressure and the boiling point of the coolant will be reduced. This can allow coolant to escape through the overflow hose.

It is very important to make sure the cooling system is filled to the proper level. BE CAREFUL NOT TO OVERFILL THE SYSTEM. It will purge itself to reach equilibrium and coolant will be discharged through the overflow.

When the radiator is filled initially or when the coolant is changed, premixed coolant should be added no faster the 20 liters (5 gallons) per minute, This reduces the chance of trapping air bubbles in the system and causing the coolant level to be too low.

Inspect the coolant level in the top tank. Bring the coolant to the proper level before testing.

An easy method to test for air or combustion gases in the cooling system is the Pressure Test using a pressurizing pump with a gauge, part no. 9S8140 or equivalent.

Remove the pressure cap and run the engine until the thermostat opens and the engine reaches operating temperature of 91 to 100°C (195 to 210°F). This will vent the normal coolant expansion.

After the temperature stabilizes install the pressurizing pump and gauge kit.

Use the pump to pressurize the system to nominal pressure of 35 to 50 kPa (5 to 7 psi). Continue to run the engine at a constant temperature and rpm (between 1500 to 1800 rpm) and monitor the gauge.

If the pressure reaches 75 kPa (11 psi) or greater within 5 to 10 minutes release it back to 34 to 48 kPa (5 to 7 psi). If the pressure rises again to 75 kPa (11 psi) or greater there probably is an internal leak that will require removal and inspection of cylinder head, gasket, injector adaptors or cylinder liners.

If there is no combustion gas leak, the gauge will remain at 34 to 48 kPa (5 to 7 psi), varying approximately 7 to 14 kPa (1 to 2 psi) when the fan comes on.

Air and gas in the system can also be checked by another simple test called the Bottle Test.

The equipment needed to perform this test is a bucket of water, a calibrated half liter or pint bottle and a length of hose attached to a modified radiator cap.

After the pressure test the engine should already be at operating temperature [90°C to 99°C (195°F to 210°F)] and the expansion air and gases vented. Install the modified radiator cap and hose. Submerge the bottle in the bucket, filling the bottle completely with water. Invert the bottle keeping the mouth under water. Place the loose end of the hose into the water-filled bottle.

Continue to run the engine at constant temperature and rpm (between 1500 to 1800 rpm). If there is a combustion gas leak, the gases will make their way to the radiator, through the hose and into the inverted bottle.

If more than 0.5 L (0.13 gal) of water per minute is displaced, air or gas entering the cooling system is excessive. Under a load condition on a dyno, 0.75 L (.195 gal) per minute would be excessive. There is probably an internal leak that will require removal and inspection of the cylinder head, gasket, injector adaptors or cylinder liners.

Repair Procedure

Cylinder Head - Bottom Deck

Remove the cylinder head from the engine to expose the bottom deck sealing surface. Before cleaning or machining of the cylinder head bottom deck, remove fuel injection nozzles/adapters from the head. Use a putty knife to scrape off any excess gasket material. With the valves still in place, thoroughly clean the bottom deck with a wire wheel or "Scotchbrite" pad. Use solvent or 8T9011 Component Cleaner to remove any oil, grease or loose carbon from the combustion surface and wipe clean.

Visually inspect the bottom deck of the cylinder head for damage. Determine if the combustion surface flatness is within specification. Occasionally, the head gasket fire ring sealing surface can suffer erosion or "Beat-In" following a gasket failure. If a depression can be felt in this area with the fingertip or fingernail, measure the depth with a 8T0455 Liner Projection Tool Group. Be sure the tool dial indicator is correctly calibrated before use.

If erosion or fire ring "Beat-In" exceeds 0.025 mm (0.001 in), the cylinder head combustion surface must be repaired by machining or the head replaced.

Erosion around the water hole is not critical if there is enough material left to support the water ferrule. Erosion in this area can sometimes be corrected with a room temperature vulcanizing (RTV) compound used to help seal the water ferrule.

Cylinder Heads - Critical Factors for Reconditioning

There are several factors which affect the amount of material that can be removed from the surface of a cylinder head. These include valve projections, surface flatness and finish. Measure these areas as well as the cylinder head minimum thickness dimensions whenever you recondition the head to block mating surface.

Before cleaning or machining of the cylinder head bottom deck, remove fuel injection nozzles/adapters from the head. On occasion, intake and exhaust valves may also require removal. Machining this surface can be accomplished with a mill, surface broach machine or surface grinder.

NOTE: Remove the minimum amount of material necessary to make the repair. Minimum head thickness following machining is 98.89 mm (3.893 in).

Surface Finish/Flatness

Machined surfaces must be smooth to form a good seal. The surface finish of the cylinder head faces must be as smooth as a new head after machining. Cylinder head flatness must not vary more than 0.10 mm (0.004 in) overall, or 0.05 mm (0.002 in) for any 152 mm (6.0 in) span.

Cylinder head flatness can be measured by using a 610 mm (24 in) straight edge for measuring the total length flatness and a 152 mm (6 in) straight edge for measuring across the sealing surface.

* Place the straight edge on the sealing surface.

* Use the feeler gauge and very carefully slide it under the straight edge.

NOTE: Clean machining debris from internal head passages prior to reassembly.

Valve Projection

After the cylinder head has been reconditioned, you must measure the valve projection. The maximum and minimum projection specifications for intake and exhaust valves are listed in the Service Manual for the engine. Excessive projection can cause the valve head to contact the piston during engine operation.

Spacer Plate

Thoroughly clean both sides of the steel spacer plate with a wire wheel or "Scotchbrite" pad. Use caution when cleaning around the liner hole with rotary abrasive pads. The spacer plate can be damaged if pad is not held parallel with the block surface. Gasket marks left on the plate are acceptable. The standard spacer plate measures 9.970 ± .025 mm (.3925 ± .0010 in). If the spacer plate has corrosion damage the thickness may vary an additional .025 mm (.001 in).

Perforated gasket core imprint - Use Again

Cylinder Liner - Inspect Flanges

Extended operation after a head gasket failure or filler band leakage can allow erosion or corrosion on the liner flange to cylinder block joint(s). Excessive amounts of erosion/corrosion damage can affect the sealing capability of the head to block joint if not corrected. In order to thoroughly inspect this joint, the cylinder packs must be removed.

Do not measure liner projection before cylinder pack removal unless necessary to verify the workmanship of a previous repair.

Remove all cylinder packs from the engine using the 8T0812 puller or equivalent. Use care when removing the packs from the block to guard against inadvertent damage to the liner seat by the connecting rod/bolts. Remove the filler bands and clean the liner flange/seat area with a hand or rotary wire brush to allow for careful visual inspection. Do not use glass beads as this process will disguise any erosion or flange cracks.

Evidence of minor fretting/dark stains or discoloration is acceptable when it is circumferential and does not prevent the liner from sealing. Groups or patches of pits/erosion occurring in random patterns under the liner flange are not acceptable; do not reuse the liner. This type of extensive damage normally occurs adjacent to similar erosion on the cylinder block.

Measure the liner flange thickness in four places, 90° apart or in eroded areas.

Cylinder Liner - Flange Thickness

Use a 6V7059 Micrometer to measure the thickness of the flange.

Measure the thickness of the flange with a 6V7059 Micrometer. Use the liner again only if it is acceptable according to the specifications in the chart below.

Liner with significant erosion/corrosion in filler band area, under liner flange and in fillet radius (crack could be hidden by glass beading or by improper cleaning) - Do Not Use Again

Liner with nick on the bottom of flange - Do Not Use Again

Damage to the fire dam. Use Again only if the damage is not extended completely across the fire dam and any burrs or sharp edges are removed.

Damage in the gasket surface area. Do Not Use Again.

Nick in the vertical flange edge. Use Again after any sharp edges or high areas are removed with a file.

Chip in the seal edge of the flange. Do Not Use Again.

Rough, pebbly surface extending in a random pattern. Do Not Use Again.

Pits and fretting under the liner flange. Large pits or groups of pits are not acceptable, especially in the radius. Do Not Use Again.

Fretting is acceptable when it is circumferential and does not prevent the liner from sealing. Measure flange thickness. Use Again.

Refer to Guideline For Reusable Parts SEBF8068 "Cylinder Liners".

Cylinder Block - Top Deck

Cylinder block top deck cleaning.

Clean the cylinder block top deck completely with wire brush or "Scotchbrite" pad. Use caution when cleaning around the liner bores with rotary abrasive pads. The liner seat can be damaged if pad is not held parallel with the block surface. This damage and its reduced seating area may cause a head joint failure shortly after engine operation has begun.

Removing burrs from top deck.

After cleaning, use a flat file to dress the top deck to remove burrs and highlight the original factory milling marks.

Milling pattern marks.

Carefully inspect each liner seat area for signs of measurable erosion. Determine measurable erosion with an 8T0455 Liner Projection Tool Group. Measurable erosion generally will destroy the milling mark pattern and exhibit a rough, pebbly surface. If erosion directly under the liner flange measures .025 mm (.001 in) deep or more with the depth gauge, record these measurements in the Service Report.

Measurable erosion under liner flange is permissible when the eroded area is not more than .025 mm (.001 in) deep. Multiple areas of erosion are also permissible if depth does not exceed .025 mm (.001 in) deep. These small areas of erosion under the liner flange are acceptable. The liner flange is designed with sufficient rigidity to span those areas without affecting sealability of the head gasket. This erosion or fretting damage is acceptable if it does not affect liner projection.

Milling marks evident, no visible or measurable erosion, liner seat areas with dark stains. Do Not Counterbore.

Milling marks evident, no visible or measurable erosion, liner seat areas with dark stains. Do Not Counterbore.

Milling marks evident, no visible or measurable erosion, liner seat areas with dark stains. Do Not Counterbore.

Milling marks evident, no visible or measurable erosion, liner seat areas. Do Not Counterbore.

Casting damage extends more than half way across width of liner seat. Counterbore to restore liner seat flatness.

Erosion and milling mark pattern measures less than 0.025 mm (0.001 in) deep. Do Not Counterbore.

Erosion and milling mark pattern measures less than 0.025 mm (0.001 in) deep. Do Not Counterbore.

Measurable erosion outside the immediate liner seat. Do Not Counterbore.

Measurable erosion occuring outside the immediate liner seat area is permissible. This erosion does not affect the stability of the liner nor the sealing ability of the head gasket. This erosion will not clean up by counterboring.

Erosion under the water ferrules and outside the liner seat area.

Erosion under the water ferrules is permissible. This erosion can be filled with 5P3321 Epoxy, a compound of liquid metal fillers or Belzona "Ceramic R".

NOTE: Machining the top deck of the block for this type of erosion around the water ferrule is NOT required.

Pebbly block surface in liner seat.

Measurable erosion of .0890 mm (0.0035 in) deep.

Rough pebbly block surface in liner seat area must be measured. Erosion measuring more than .025 mm (0.001 in) deep must be removed by counterboring. Repair this damage by counterboring the block deck and installing the thinnest possible stainless steel insert.

Cylinder Block - Counterbore For Liner Seat Inserts

Counterbore only the block liner seats that exhibit measurable erosion of 0.025 mm (0.001 in) or greater. Generally, liner seat erosion resulting from a head gasket failure require counterboring only one or two cylinder liner seats. Use only stainless steel inserts. The part numbers are 9L5855, 9L5856, 9L5857 and 9L5858.

Protected crankshaft journal.

When machining work is done on a cylinder block, special precautions are required to protect other engine components from contamination. Protect the crankshaft rod journals adjacent to the repair by covering with paper towels and taping. Cover the lifter bore area with paper towels or foam inserts. Tape or coat with heavy grease the oil supply dowel to prevent chip entry.

Installation of counterbore tool.

Install counterboring tool and tighten the hold down bolts to a torque of 68 N·m (50 lb ft). A counterboring tool, equipped with a dealer fabricated handle for continuous rotation of the tool, provides a smoother cut than a tool equipped with a "Tee" style handle. Continuous rotation of the tool reduces tool chatter caused by start-stop rotation. Machine a maximum of 0.10 mm (.004 in) for any one dial setting.

Depth gauge.

Use depth gauge to measure progress when nearing the depth needed to install the thinnest insert. Reduce machine depth to .025 mm (0.001 in) per cut until reaching the final depth. Measure to verify actual insert thickness and install insert so that it is flush with the top of the block within 0.013 mm (.0005 in).

NOTE: The bore in the block for the insert should be 144.051 ± 0.025 mm (5.671 ± .001 in).

Left: A good counterbore. Right: Chatter marks must be cleaned up before assembly.

Counterbore machining.

If counterboring to the depth of the thinnest insert does not clean up 100 percent of the erosion/crack damage, machine to the depth of the next insert.

NOTE: At the time of installation, the stainless steel inserts are installed dry (WITHOUT the use of sealants).

1. The design of insert (1) and the size of the counterbore give the insert a slip (loose) fit in the cylinder block. The outer diameter of the counterbore is 144.051 ± 0.025 mm (5.671 ± .001 in). If the counterbore has been cut correctly, the top of the insert will be even or within 0.0127 mm (0.0005 in) of the top surface (A) of the cylinder block to give the necessary projection for the cylinder liner. Location (B) shows the liner seat area that must clean up 100 percent before it is permissible to install an insert in the counterbore. The radius (C), 0.64 ± 0.13 mm (0.025 ± 0.005 in), is determined by the cutting tool.

2. There is a plus or minus tolerance for the thickness of the insert and for the depth of the counterbore. When inserts are installed in a cylinder block, there must be no more than 0.05 mm (0.002 in) difference in height between the inserts of any two counterbores that are next to each other. It is necessary then, to measure the depth of each counterbore and install an insert of the correct thickness to give the 0.05 mm (0.002 in) specification. The insert thickness should be measured prior to installation to determine the plus or minus tolerance.

Counterbore deburring.

When machining is complete, deburr both edges of the counterbore with emery paper or #400 wet-dry sandpaper. Use a wet-dry vacuum to remove cuttings from cylinder bores, water jacket and head bolt holes. Remove plastic bore plugs, foam inserts, paper towels, tape and all other protective covers. If necessary, run threaded tap down head bolt holes to remove burrs and thoroughly clean out head bolt holes. Wash down cylinder block with solvent or use pressure air to ensure block/crankshaft/lifter bore cleanliness. Install inserts dry (no sealant) with chamfer facing down.

Cylinder Liner Projection

NOTE: This procedure alleviates the need for the "H" bar to hold down liners during projection measurements.

Illustration 1.
Liner projection components

1. Bolt.

2. Hard washer.

3. Washer.

4. Fabric washer.

5. Spacer plate.

6. Spacer plate gasket.

7. Cylinder liner.

8. Block.

Install clean liners or cylinder packs (without the filler band or the rubber seals), spacer plate gasket and clean spacer plate.

Install bolts and washers, as indicated previously, in the holes indicated with an X. Install all bolts or the six bolts around the liner. Tighten the bolts to a torque of 95 N·m (70 lb ft).

Use the 8T0455 Liner Projection Tool Group to measure liner projection at positions indicated with and A, B, C and D. Record measurements for each cylinder. Add the four readings for each cylinder and divide by four to find the average.

If the liner projections are out of specification, try rotating the liner or install the liner in another bore to see if the measurements improve.

Do not exceed the maximum liner projection of 0.175 mm (0.0069 in). Excessive liner projection will contribute to liner flange cracking.

With the proper liner projection, mark the liners in the proper position and set them aside.

When the engine is ready for final assembly, the o-ring seals, cylinder block and upper filler band must be lubricated before installation.

If the lower o-rings are black in color, apply liquid soap on the lower o-ring seals and the cylinder block. Use clean engine oil on the upper filler band.

If the lower o-rings are brown in color, apply engine oil on the lower o-ring seals, the cylinder block and the upper filler band.

NOTE: Apply liquid soap and/or clean engine oil immediately before assembly. If applied too early, the filler bands may swell and be pinched under the liners during installation.

Head Bolts

Inspect head bolts for reusability. Replace the head bolts that have surface damage (pitting or erosion) on the shank that cannot be polished smooth.

The high stress areas on a bolt are:

1. The first exposed thread root on the joint side of the nut or tapped hole.

2. The first thread root after the shank.

3. The underhead fillet.

Damage in these areas can lead to bolt failure.

Corrosion on bolt shank. Do Not Reuse.

Corrosion on bolt shank. Do Not Reuse.

Combustion gas leakage can lead to corrosion on the bolt shank. If this corrosion damage cannot be removed with emery paper or wet-dry sand paper, replace the bolt. Any remaining irregular surfaces would create unnecessary stress raisers and ultimately weaken the bolt.

Final Engine Assembly

Use a 1P2991 Tap to remove burrs from each head bolt hole. Thoroughly clean each hole to remove excess fluid and debris which would affect final torque values.

Lightly coat the head bolt threads, washers and bottom of bolt heads with 6V4876 Molykote Paste Lubricant. Use of this friction reducing paste will significantly improve the load on the head gasket. Do not use oil.

Install the head gasket dry. Remove excess oil/grease from the top of the liner flanges, spacer plate and bottom of the cylinder head with solvent or preferably 8T9011 Component Cleaner.

1. Clean the surfaces of the cylinder head and the cylinder block that make contact with each other. Make sure the surfaces are clean and dry. Install a new dry gasket (2) on the cylinder block.

2. Fasten a hoist to the cylinder head (1) and put it in position on the cylinder block.

3. Put 6V4876 Molykote Paste Lubricant on all the head bolts and rocker shaft bolts.

NOTE: Do not tighten bolts at this time.

4. Loosen the adjusting screws on the rocker arms for valve clearance. This will prevent a bent valve or push rod at installation.

5. Install push rods (4) and rocker shaft assembly (3). Install the bolts and washers that hold the rocker shaft in place.

6. Tighten the bolts as follows:

(1) Large bolts. Put 6V4876 Molycoat on bolt threads and between washer and underside of bolt heads. Tighten bolts in the following step sequence.

a. Tighten bolts from 1 through 26 in number sequence to a torque of ... 155 N·m (115 lb ft).

b. Tighten bolts from 1 through 26 in number sequence to a torque of ... 250 ± 17 N·m (185 ± 13 lb ft).

c. Tighten bolts from 1 through 26 in number sequence again to a torque of ... 250 ± 17 N·m (185 ± 13 lb ft).

d. Tighten bolts A through G in letter sequence (hand tighten only) to a torque of 43 ± 7 N·m (32 ± 5 lb ft).

6. Make an adjustment until the intake valve lash is 0.38 mm (.015 in) and the exhaust valve lash is 0.64 mm (.025 in). Tighten the locknuts (5) for the adjusting screws to a torque of 29 ± 7 N·m (21 ± 5 lb ft).

7. Connect tube assembly (6) and install the bolts to fasten clips (7).