CAMPAIGN: DIESEL FUEL QUALITY MAY CONTAIN A HIGH GUM LEVEL. GMC Truck GMC MD Conventional (C Model) 1990

SUBJECT: DIESEL FUEL QUALITY

MODELS: 1990 TOPKICK/KODIAK EQUIPPED WITH 3116 CAT ENGINES

It has been brought to our attention that a number of Chevrolet VINs were inadvertently added to Campaign 90C09. ONLY VEHICLES WITHIN THE FOLLOWING BREAKPOINTS ARE INVOLVED:

GMC: SOP thru LJ601811 CHEVROLET: SOP thru LJ201169

Vehicles produced after the above breakpoints were built with the correct fuel quality.

Vehicles built prior to the VIN breakpoints including those at body builders may have the fuel quality concern listed above and must have that fuel purged if the vehicle has not been delivered to a customer. Those vehicles which have some time/mileage on the engine will not exhibit engine performance concerns. Arrangements for this procedure must also be made for all vehicles in process at upfitters or body builders which are within the VIN breakpoints.

SUBJECT: Diesel Fuel Quality

MODELS: 1990 TopKick/Kodiak Equipped with 3116 CAT Engines

Initial build diesel units may have been fueled at the plant with a fuel containing a high GUM level.

A service procedure for fuel purging which includes changing of the fuel filters was transmitted via DCS on 1/13/90 and included VIN breakpoints.

A small number of vehicles described in the DCS of 1/13/90 may exhibit excessive valve train noise. This noise can be attributed to one or more stuck exhaust valves and the resulting damage to the engine can include loose valve and injector pushrods resulting from the high GUM level fuel. The loose pushrods may damage the engine camshaft, lifters, side covers, and/or other associated parts.

For engines which do develop a noise condition, repair should be done in-chassis. To date, no piston-to-valve contact has occurred. The head can be repaired without being removed by carefully loosening the stuck valves. It should not be necessary to remove any of the injectors, or the injector control shaft assembly or governor, unless these components were damaged during the failure. Bring the pistons to top dead center (two cylinders at a time), remove the valve retainers, valve springs, valve seals, etc. A tool to compress valve springs can be fabricated. The instructions for fabricating this tool, and the procedure for removing valve springs without dropping the valves into the cylinders can be obtained from the GMC Technical Assistance Center or from your Caterpillar distributor. You will need to request a copy of the article, "New Valve Stem Seal Used on Inlet Valves and Added to Exhaust Valves", found in the Service Magazine, dated May 15, 1989.

IMPORTANT: The 3116 truck engines already have the new valve seals that were announced in this article.

After the valve springs and valve seals have been removed, apply Caterpillar 1U8265 Penetrating Oil or an alternate solvent such as Kroil (R), 3M (R) Five-Way, or Loctite (R) Penetrating Oil to assist in loosening stuck valves. DO NOT use pliers or hammer the valve stem tips directly to loosen them as the valves could be damaged or bent. Use only a soft mallet or a wood block on top of the valve stem to tap against. When the valve begins to loosen, rotate the engine slightly to lower the piston so the valve can be moved up and down sufficiently to aid in complete loosening. DO NOT let the valve fall into the cylinder. After loosening each valve, lubricate with clean engine oil before reinstalling valve seals and springs.

IMPORTANT: When repairing an engine with stuck valves, use penetrating oil or other solvent to remove deposits on ALL valves, not just the stuck valves.

"We believe these sources and their equipment to be reliable. There may be additional manufacturers of such equipment. General Motors does not endorse, indicate any preference for or assume any responsibility for the products or equipment from these firms or for any such items which may be available from other sources."

Replace other damaged parts as needed. If pushrods have fallen past the camshaft into the oil pan, be sure to check piston cooling jets for damage while the pan is removed. Reassemble engine. Set fuel timing and valve clearance settings. The 1U6680 tool group will be needed. See the procedures in the testing and adjusting section of the 3116 Truck Engine Service Manual, form X-9059. The 3116 Parts Book is Form SEBP1879, and is available at your Caterpillar distributor. After repair, follow the service procedure for replacing the fuel with kerosene as outlined in the prior DCS message on this subject.

IMPORTANT: Make sure that all dealership personnel and customers that will start a diesel powered TopKick/Kodiak are aware of the starting procedure for this vehicle. Refer to starting procedures beginning on page 23 of the Operation and Maintenance Manual for the 3116 engine, found in the glove compartment of each vehicle.

Labor Op Information: (GMC Truck Division warranty claim)

V5831 Straight time labor operation is to be used to make necessary repairs to correct valve train noise caused by the incorrect fuel.

Note: This labor operation requires GMC Truck straight time documentation as outlined in the Claims Processing Manual section II.R.c&d (page 7). This labor operation will also require DCS claim comments and approval from your District Service Manager or service Development Manager. All parts used in this repair procedure must be retained indefinitely for GMC Truck inspection.

SUBJECT: Diesel Fuel Quality

MODELS: 1990 TopKick/Kodiak Equipped with 3116 CAT Engines

Initial build diesel units may have been fueled at the plant with a fuel containing a high GUM level.

Vehicles produced after the following VIN breakpoints were built with the correct fuel quality.

GMC: LJ601811 Chevy: LJ201169

Fuel Purge Procedure:

Drain the factory supplied fuel from the vehicles tanks. The amount of fuel to be drained will be 10 to 22 gallons for single tanks and 25 to 47 gallons for vehicles equipped with dual tanks.

CAUTION:

To prevent an accident when working on the fuel system, disconnect the vehicle battery ground (-) cable(s) and provide fire fighting and safety equipment, as required by dealership policies and local regulations.

1. The engine control switch must be in the "OFF" position.

2. Remove the drain plug(s) from the base of the tank(s).

IMPORTANT: When draining any tank, always make sure that your container is large enough to handle all the fuel drained from the tank, is sealable and is in good condition.

3. Dispose of the factory supplied fuel properly. DO NOT reuse this fuel.

4. Install the drain plug(s) after all of the fuel has drained from the tank.

5. Fill the tanks with 10 to 20 gallons of Kerosene.

6. Remove the engine mounted secondary fuel filter.

7. Clean the gasket sealing surface of the fuel filter base. make sure all of the old gasket is removed.

8. Apply clean diesel fuel (or kerosene) to a new filter element (Caterpillar part number lP2299) gasket. Do not "prefill" this filter.

9. Install the new filter element on the fuel filter housing base. Tighten the filter element by hand until the gasket seats, then tighten 3/4 of a turn more.

10. Remove the plug on the top out-board side of the fuel filter housing base (see pg. 75 of Diagnostic Procedure and Maintenance Manual). Use a squeeze bottle filled with kerosene to slowly fill the filter through the plug hole.

11. Install the plug in the fuel filter housing base after the filter is full of kerosene.

12. Remove the frame-mounted primary fuel filter element.

13. Clean the gasket sealing surface of the fuel filter base. Make sure all of the old gasket is removed.

14. Apply clean diesel fuel (or kerosene) to the filter element gasket. Fill the new filter element (part number 25010776 EXC. RPO NWB (fuel/water separator) or 15618921 W/ RPO NWB) with clean filtered kerosene until full.

15. Install the new filter element on the cover assembly. Tighten the filter element by hand until the gasket seats, then tighten to 13 ft.lbs (17 N.m).

16. Start the engine according to the starting procedure found on the beginning of page 23 in the Caterpillar Operation and Maintenance Manual for TopKick/Kodiak Medium Truck Models. Also refer to pages 74 and 75.

IMPORTANT: There should be enough residual fuel in the system to allow the engine to start. If the engine runs and then stops, crank the engine for a period of 30 seconds, then allow the starter to cool for 30 seconds. Repeat this cranking and cooling cycle until the engine starts and runs.

17. After the vehicle has reached operating temperature, it should be allowed to run for one-half hour to help reduce any deposits on the valve stems which have already formed. Then slowly increase engine speed to maximum throttle, and return to idle. Repeat this step 5 times. Stop the engine immediately if unusual noises develop.

Parts Information: Part Number Quantity --------------------------------------- ----------- -------- Secondary filter element (engine mounted): 1P2299 1

Part is currently available from Caterpiller.

Primary filter element (chassis mounted): 25010776 1 EXC. RPO NWB (Fuel/Water Separator)

Part is currently available from GMSPO.

Primary filter element (chassis mounted): 15618921 1 W/ RPO NWB (Fuel/Water Separator)

Part is expected to be available on January 22, 1990. Until then normal part orders will not be accepted by GMSPO. Only verifiable emergency VIP orders will be accepted. All parts will be placed on 400 control to waive VIP surcharges. However, the part will be shipped premium transportation at dealer's expense. All other order types will be canceled as incorrectly ordered while the 400 control is in place.

Labor Op Information: (GMC Truck Division warranty claim)

V5830 0.8 Hrs. Drain Fuel Tank and Change Filters

add 0.4 Hrs. For vehicles with second fuel tank

In certain situations when improper starting procedures are used in extremely cold ambients in combination with poor fuel quality the possibility of stuck exhaust valves or loose push rods may exist.

IMPORTANT: Should the vehicle exhibit unusual valve train noise contact the GMC Truck Technical Assistance Center immediately so that a TAC case may be initiated.

Information and Labor Operation information for valve train repairs will follow.

General Motors bulletins are intended for use by professional technicians, not a "do-it-yourselfer". They are written to inform those technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions and know-how to do a job properly and safely. If a condition is described, do not assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See a General Motors dealer servicing your brand of General Motors vehicle for information on whether your vehicle may benefit from the information.