Product Support Program For Replacing Failed Cylinder Head Gaskets On Certain 3406B Truck Engines Caterpillar

Only items directly referred to under the heading "Parts Needed " are applicable to this program.

Testing for cylinder head cracks (external and internal) and replacement for these reasons is not part of this program.

It is no longer necessary to check timing advance unit operation.

Inspection of the cooling jets is included in the time allowed to R & I cylinder packs (1239-010).

If claiming more oil than specified in the Operation & Maintenance Guide, such as engines equipped with Luberfiners, document the need for additional oil in the claim story.

Parts Disposition

Cosa Dealers

Handle the parts in accordance with your Warranty Bulletin on warranty parts handling.

All Other Dealers

Warranty claim parts that do not involve core credit must be held for 30 days after the Caterpillar Claim Register Date. Warranty claim parts that involve core credit must be held for 15 days after the Caterpillar Claim Register Date.

NOTE: Failure to clearly mark the areas of damage on all of the parts can result in claim credit being denied.

Head To Block Joint Repair Guideline

NOTE: This is Caterpillar's recommended procedure for the repair of 3406 Engine cylinder head gasket failures.

Contents

Fuel System

For governors that are not factory sealed, check fuel settings and record the actual and factory specifications in the Service Report. This program cannot be applied to engines not found within factory specs.

NOTE: It is not necessary to measure fuel settings on PEEC engines.

Exhaust Gas Leakage Tests

Coolant loss and aeration can be caused by reasons other than exhaust gas leakage. (OEM bleed system, overfilling or rapid fill, air compressor leakage, faulty radiator cap, etc.) See the August 1990 Truck Engine News. Perform a test to detect exhaust gas leakage into the coolant.

Exhaust leaking past the fire ring seal will normally escape into the atmosphere or coolant. Unless the leak is severe, detection of leakage into the coolant will require further investigative testing for verification.

Two methods can be used to verify head gasket fire ring damage.

If exhaust gas leakage is not detected and verified, this program does not apply.

1. Install a modified radiator cap, or cooling system test adapter, that prevents a buildup of system pressure for the bottle test. Run the engine until reaching operating temperature of 85 °-99° C (186°-210° F). Fill a clear bottle with water and place the overflow tube or extension from the cap or adapter into the bottle. If exhaust gas is entering the cooling system, a consistent flow of bubbles will be visible in the water; fire ring damage is likely.

2. Install system pressurizing pump/gauge kit part no. 9S8140 or equivalent and run the engine until reaching operating temperature of 85 °-99° C (186° - 210° F). Pressurize the system to nominal pressure 35-48 kPa (5-7 PSI) with the pump and continue to run the engine. Monitor the gauge and if pressure continues to rise during engine operation, fire ring damage is likely.

With exhaust gas leakage verified and the governor settings found within factory specifications, this program can be administered.

Clean

Steam clean the engine if needed before disassembly.

Cylinder Head - Bottom Deck

Thoroughly clean the cylinder head bottom deck with a wire wheel or Scotchbrite pad. If erosion or fire ring beat-in exceeds .025 mm (.001 ") in the fire ring sealing area as measured with the 8T0455 liner projection tool kit, repair by machining while maintaining minimum head thickness specifications of 111.51 mm (4.390 "). Intake and exhaust valves and bridge dowels may occasionally require removal to machine the head bottom deck. See the Service Manual.

If damage is excessive and/or if time constraints dictate defined as more than a 24 hour turnaround to complete machining), use a remanufactured cylinder head.

NOTE: Cylinder heads with internal or external cracks are not claimable under this program.

Cylinder Head-drill Coolant Passages

To improve coolant flow within the rear section of the existing cylinder head, drill two new coolant flow passages through the top and intermediate decks of the head. (See the illustrations.) The coolant flow passages must be drilled before proceeding with the head gasket repair. If using a parts stock cylinder head, see the June 1992 Truck Engine News.

Remove the cup (core) plug from the rear face of the cylinder head. This plug is often hidden from view by the rear engine lifting eye. The rear head coolant passage and exhaust port wall will be visible. Measure the distance from the rear face of the head to the wall of the exhaust port. This dimension will vary on every cylinder head due to casting variations. Locate the centerline of the new drilled hole so that the drill bit does not contact the exhaust port wall. Do this by subtracting a minimum of 8.1 mm (.32 ") from the measured dimension. Locate and mark the cylinder head center line. (See illustration.) This centerline extends through the nozzle adapter holes. The first step is to use a " drill bit and drill a 15 mm (.594 ") diameter hole 85 mm (3.35") deep. approximately 25.4 mm (1.00 ") from the bottom surface of the head). Do not exceed this depth as damage to the bottom deck may occur. Use the existing hole as a pilot. Use a "drill bit and enlarge the hole to 18 mm (.719 ") diameter and to 20 mm (.79") deep. Tap the hole to accept an -14 NPTF threaded pipe plug.

Remove the existing pipe plug from the right rear corner of the cylinder head top deck. Visible inside is a 5 mm (.20 ") diameter bleed hole. Use a " drill bit and enlarge this hole to a 15 mm (.594 ") diameter by drilling 85 mm (3.35") deep. Use care not to damage the existing pipe threads. Clean up threads if necessary.

NOTE: Some older version heads have inch pipe plug in this location. The inch pipe plug can be retained or it can be enlarged to a inch pipe plug using drill diameters given above.

Clean the chips from both holes using a magnet. Scrape out any existing sludge from the newly exposed cavities to improve heat rejection. Install the new and previously removed pipe plugs with thread sealant. Press in a new cup (core) plug 2M6471 with 7M7456 Bearing Mount or 6V6640 Liquid Gasket on the outside diameter to prevent leakage.

Spacer Plate

Use care when removing and handling aluminum spacer plates to retain maximum reusability. Before cleaning the spacer plate perform a quick visual inspection for bending (warping), deep scratches or cuts, wide cracks, heat or impact damage. Hairline cracks do not necessarily prevent the reuse of the spacer plate. The Guideline For Reusable Parts, SEBF8131, clarifies the reuse guidelines for 3400 engine spacer plates. Do not reuse a spacer plate that has cracks with spalling of material or scorch paths from prolonged exhaust gas leakage.

Cracks without measurable width (hairline) are permitted between the large head bolt holes and the large cylinder liner clearance holes or valve train pockets. Hairline cracks are also permitted between adjacent large cylinder liner clearance holes as these cracks do not affect the function of the spacer plate. Cracks or connecting surface depressions across the outside perimeter of the plate on either side are not permitted. These characteristics may create paths for external fluid leakage. Mark the damaged area(s).

Glass beading is the preferred cleaning method. Do not scrape the plate with a steel putty knife or sand the surface with sandpaper, wire brush or wheel. The standard spacer plate should measure 8.585 ± 0.025 mm (0.338 ± .001"). The thickness may vary up to 0.025 mm (.001 ").

Also see section on parts service spacer plate.

Cooling Jets

Remove the cooling jets before cylinder pack removal to avoid damage to the jets.

Cylinder Packs

NOTE: 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 IU6318 puller or equivalent. Use care when removing the packs from the block to guard against inadvertent damage to the liner seatby the connecting rod/bolts. Refer to Guideline For Reusable Parts SEBF8068 "Cylinder Liners". Inspect each liner wall outer diameter for deep pitting [greater than 2.23 mm (.090 ")] that would prevent reusability.

NOTE: Regardless of other damage, liners with deep pitting caused by poor cooling system maintenance are not claimable under this program.

Remove the filler band and clean the liner flange/seat area on the remaining liners with a wire brush to allow for careful visual inspection. Liner flange thickness measurement is no longer a criteria to determine liner reusability under this program. Perform a visual inspection of the seating surface (bottom) of the liner flange per the reuse guide. 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.

Mark the damaged area(s) with a paint stick or similar marker. See the Service Claim Allowances.

Piston Pin Retainers

Retainers on assembled cylinder packs are visible by pulling the pistons halfway out of the bottom of the liners exposing the pin bores. Replace all 8N7295 piston pin retainers with 7E5665 retainers.

Piston Reusability

Piston pin retainer groove wear is excessive when:

1. The piston pin cannot be slid out easily across either retainer groove due to metal displacement. It is normal for some pins to resist movement within the piston bores at room temperature. Clearances increase during engine operation.

2. The installation of the 7E5665 retainer does not provide a tight fit in the groove or rotates easily.

NOTE: Piston or cylinder pack replacement is not claimable under this program. A piston judged not reusable due to piston retainer groove wear, may be claimed as replacement cylinder packs against the March 26, 1992 Service Letter - PS0600.

Cylinder Block - Top Deck

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 may allow the liner to sink after operation due to reduced seating area. After cleaning, use a flat file to dress the top deck to remove burrs and highlight the original factory milling marks. Carefully inspect each liner seat area for signs of measurable erosion. Determine measurable erosion with an 8T0455 liner projection gauge kit 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 ") deep or more with the depth gauge, record these measurements in the Service Report. Repair this damage by counterboring the block deck and installing the thinnest possible stainless steel insert from the parts list. Measurable erosion occurring 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. A certain amount of measurable erosion under the water ferrules is permissible. Excessive erosion may be filled with 5P3321 Epoxy, 8T9022 RTV Compound, or liquid metal filler. Remove excess compound to level even with the block surface.

Cylinder Block - Counterbore For Liner Seat Inserts

NOTE: Counterboring all six liner seats to improve liner projection is not claimable under this program. (See section on new service spacer plate.)

Counterbore only the block liner seats that exhibit measurable erosion of .025 mm (.001 ") 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. (See parts list.)

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. Install plastic cylinder bore plugs into the lower bore to keep chips off the crankshaft (use Kent Moore USA part no. PT-2000-101 or equivalent). Tape, plug or coat with heavy grease the two oil supply dowels/holes to prevent chip entry.

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 speed handle provides a smoother cut than a tool equipped with a "Tee" style handle by reducing tool chatter caused by start-stop rotation. Machine a maximum of .10 mm (.004 ") for any one dial setting. Use depth gauge to measure progress when nearing the depth needed to install the thinnest insert (9Y3368 Insert) .824 mm (.0324 " thick). Reduce machine depth to .001" 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 .013 mm (.0005 "). Ensure that the machined counterbore is level in four spots and free of tool chatter marks.

If counterboring to the depth of the thinnest insert does not clean up 100% of the erosion/crack damage, machine to the depth of the next insert. The 2W3815 Insert is 1.595 mm (.0628 ") thick. Caterpillar recommends counterboring only to the depth of the thickest available stainless steel insert. The thickest available stainless steel insert is the 5N0093 Insert. The 5N0093 Insert is 2.700 mm (.1063 ") thick. Contact your Caterpillar Dealer or service rep. if damage extends deeper than described above.

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 pressurized air to ensure block/crank/lifter bore cleanliness. Install inserts dry (no sealant) with chamfer facing down.

Liner Projection

The liner projection specification is .025-.152 mm (.001" -.006"). (Also see section on new parts service spacer plate.)

NOTE: The following procedure is for checking liner projection during final assembly.

Replace all liner filler bands and o-rings. Lubricate the filler bands with oil and lubricate the "black" o-rings with liquid soap and the "brown " o-rings with oil. Install the cylinder packs with new connecting rod bearings before the filler band swells. Install oil supply dowels (if removed), spacer plate gasket and spacer plate. Bolt down the cylinder liners and spacer plate with 7K1977 Fiber Washers, 8F1484 Washers and 7H3598 bolts (6/cylinder or 26 total). Be sure the fiber washers are placed below the 8F1484 Washers so that no damage is done to the spacer plate or liner flanges. This method alleviates the need for the "H" bar to hold down liners during projection measurements. Tighten the bolts evenly in 3-4 intervals up to a maximum of 70 ft-lb (95N-m). Use the 8T0455 liner projection tool group to obtain four measurements on each liner flange. Besides the allowable range for the entire set of liners .025-.152 mm (.001 "-.006"), the maximum differential between high and low measurements made at 4 places around each liner is .051 mm (.002 "). The average projection of liners next to each other must not be more than .051 mm (.002 "). The maximum difference of all average measurements of all liners must not exceed .102 mm (.004 ").

Spacer Plate - New Parts Service

A new 6I3189 or 6I4303 Spacer Plate is available for parts service. The 6I3189 and 6I4303 Spacer Plate is .076 mm (.003 ") thinner than the production 2W8601 Spacer Plate. It can compensate for repairs that produce liner projection less than .076 mm (.003 "). It can be used when liner projection across all six cylinders is consistent but near minimum specification of .152 mm (.001 "). If inspection of the block top deck reveals no measurable damage directly under the liner flanges but the average liner projection is less than .076 mm (.003 "), this new service spacer plate can be installed.

NOTE: Use of the service spacer plate in situations that result in excessive liner projection greater than .152 mm (.006 ") is not an acceptable repair.

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

Final Engine Assembly

Install the cylinder head bolts and tighten to the correct specifications and sequence. Follow the new instructions. See Illustration 3.

Illustration 1

Illustration 2

Illustration 3