3176 Cylinder Head Gasket Repair Procedure{1124} Caterpillar

3176 Cylinder Head Gasket Repair Procedure{1124}

Usage:

Introduction

This Special Instruction contains the necessary procedures and information for checking cylinder head gaskets.

Reference: Service Manual

Cylinder Head Gasket Failure Identification

A 3176 cylinder head gasket failure can be identified by the following failure modes:

Scheduled oil sample sodium reading of 300 ppm or greater.

Verify that the engine oil has been changed within the recommended intervals and confirm the sodium reading with a Caterpillar SOS test. If unsure of the oil change interval, perform an oil change at customer's expense and schedule truck for retest.

A coolant leak can also be caused by an improperly installed injector sleeve. To eliminate this possibility, perform the following test.

1. With cylinder head on engine, remove all injectors.

2. Pressurize cooling system to 69 to 83 kPa (10 to 12 psi).

3. Check for coolant leak at bottom of brass injector sleeve.

4. If leak is detected, remove leaking sleeve and install new 4P7135 Injector Sleeve.

5. If no leak is detected, continue with procedure.

Visible coolant leak between cylinder head and spacer block.

Verify coolant leak by pressurizing the coolant system to 69 to 83 kPa (10 to 12 psi) and observing leakage.

NOTE: Check for leaks with engine cold and engine warm.

Excessive combustion gas leakage into the cooling system.

Bottle test to verify combustion gas leakage using the following steps:

1. Attach a hose to the radiator top tank. The hose must not be restricted by the pressure cap.

2. Route the hose to a bucket of water.

3. Operate the engine at 1800 rpm until coolant temperature is stable.

NOTE: If possible install engine on dyno and under load bring engine up to operating temperature.

4. Fill a one liter graduated container with water. Invert the container in bucket and place hose end into container.

5. Measure the time required to push 500 mL (0.53 quart) of water from container under load and 300 mL (0.32 quart) with no load.

6. If the time required in step 5 is less than one minute, an unacceptable combustion leak is present.

7. A coolant leak can also be caused by an improperly installed injector sleeve. To eliminate this possibility, perform steps 1 through 5 in "Scheduled oil sample sodium reading of 300 ppm or greater" on page 1.

Repair Procedure

1. Parts Inspection And Reusability

Cylinder Head

Clean bottom deck of cylinder head and inspect for obvious cracks and fire ring damage. Resurface cylinder head to remove visible fire ring damage [minimum cylinder head thickness is 104.6 mm (4.12 in)]. After machining cylinder head, inspect bottom deck for cracks between all four valves including inlet valve flycuts. Clean machining debris from ports and other passages prior to installation.

NOTE: Install remanufactured cylinder head if machining cost exceeds remanufacture cost or machining turn around time causes undo hardships to the customer. Cylinder heads can be machined without removing valves.

Oil Filter

Cut and inspect oil filter during head gasket repair. Coolant can cause the paper element and center tube to deteriorate allowing filter material to plug the lube passages. If filter element or center tube has been damaged by coolant, the lube passages must be flushed and adequate flow to crankshaft, camshaft, rocker arms and piston cooling jets must be verified. Pressure air is the preferred method of cleaning lube passages.

Spacer Block

Clean surface. Reusable.

Head gasket pattern. Do not remove indentations. Reusable.

Acceptable pitting. Reusable.

Unacceptable pitting. Do not use again.

Unacceptable erosion. Do not use again.

Impact damage. Do not use again.

Inspect spacer block for damage, erosion and pitting.

Measure flatness of the spacer block with spacer block installed on engine by using a straight edge and feeler gage. If a .002 inch or greater gauge can be inserted between spacer block and straight edge, the spacer block should be replaced.

NOTE: When measuring flatness, secure spacer block to cylinder block.

Cylinder Block

If the spacer block is removed due to damage caused by a head gasket failure, corrosion on cylinder block under the liner seal may be visible. This corrosion does not affect liner projection or the sealing capability of the liner seal. Clean corrosion by hand with a wire brush.

Show/hide table

NOTICE

Do not damage or round off liner seating area. Do not replace cylinder block.

Cylinder Liners

Reusable.

Fire ring erosion. Do not use again.

Inspect cylinder liners for fire ring damage. A fire ring mark on the liner is acceptable and the liner should not be replaced. If a wear step, fretting, or pitting is found on the liner, replace the liner.

Rebuild

Spacer Block

Reference SIMS data for head bolt thread depth update. Depth of the bottom full thread should be 143 mm (5.6 in) from the top surface of the spacer block. Bottom tap holes if work has not been completed. Clean spacer block lightly with hand held Scotchbrite pad. Do not use heavy strokes with pad. Do not use power tools or sharp tools (chisels, screwdrivers, etc.) to clean spacer block.

It is unnecessary to remove all residual black gasket coating material from the spacer block. However, gasket material should be removed near liner bore area in order to accurately measure liner projection. If a perforated core gasket (6I0104, 6I2009 or 4P2004) was previously on engine, indentations from the perforations may be visible on the spacer block surface. Do not attempt to remove these indentations.

Remove coolant and oil from all head bolt holes.

Before installing head gasket, clean spacer block with alcohol or Cleaner Solvent (8T9011) to remove all oil, coolant and dirt.

Cylinder Liner Projection

Use the procedure that follows to measure cylinder liner projection.

NOTE: The use of conventional cylinder liner projection tooling can cause damage to the sealing surface of the aluminum spacer block.

1. Clean the cylinder liner flange and spacer block surface. Remove any nicks on the top of the spacer block.

Location of components required to retain the cylinder liner and spacer block when measuring cylinder liner projection.

2. The illustration and chart identify the components required. An 8T0455 Cylinder Liner Projection Indicator Group is also required.

3. Assemble the components as shown in the illustration. The 7K1977 Washer (4) is make of a cotton fabric that is impregnated with resin. It will not damage the sealing surface of the block spacer.

NOTE: Inspect washer before measuring liner projection and replace if worn or damaged.

4. Tighten bolts (1) evenly as follows:

a. First tighten each bolt to 27 N·m (20 lb ft)

b. Tighten each bolt to 54 N·m (40 lb ft)

c. Tighten each bolt to 68 N·m (50 lb ft)

d. Tighten each bolt again to 68 N·m (50 lb ft).

5. Loosen bolt (5) until dial indicator (6) can be moved. Place gauge body (7) and dial indicator (6) on the long side of gauge (8).

6. Slide dial indicator (6) down until the point contacts gauge (8) and moves the needle 1/4 revolution clockwise to a vertical position. Tighten bolt (5) and zero indicator (6).

7. Put gauge body (7) on the spacer plate, with the indicator point on the liner flange. Read the dial indicator to find the amount of liner projection. Check projection at four locations (90 degrees apart) around each cylinder liner. Liner projection must be 0.040 to 0.200 mm (0.0016 to 0.0079 in). The maximum allowable difference between high and low measurements made at four places around each liner is 0.05 mm (0.002 in). Difference in the average projection of the liners must not exceed 0.10 mm (0.004 in) and difference in the average projection of adjacent liners should not exceed 0.05 mm (0.002 in).

8. If a liner does not meet the liner projection specifications, check the thickness of the spacer block [100.00 ± 0.05 mm (3.937 ± 0.002 in)] and the liner flange [100.12 ± 0.03 mm (3.942 ± 0.001 in)] to determine if they are correct. If not within specification, replace and repeat the liner projection measurements.

Cylinder Head

Clean bottom deck of cylinder head with Scotchbrite (power tool is OK). After removing carbon build-up from head, clean with alcohol or 8T9011 Cleaner Solvent prior to installing head on spacer block.

When installing head, use guide studs to prevent damage to the head gasket.

Inspect head bolts and replace if the shanks are pitted from corrosion. Apply a small amount of 6V4876 Molykote Paste Lubricant to the head bolt threads, under bolt head and on both sides of the washers prior to assembly. Wipe Molykote build-up from bolts to avoid contaminating the head gasket sealing surfaces.