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CAMPAIGN: AIR COMPRESSOR MOUNT BRACKET BOLTS MAY LOOSEN

AIR COMPRESSOR MOUNTING BRACKET

1987-1988 C6/C7, B6, S7 and P6 with 8.2L DDAD Engines (LH3/LH4) and with One-Piece Air Compressor Mounting Bracket (KYA/K55/K56)

General Motors of Canada has determined that certain 1987-1988 Medium Duty Trucks equipped with 8.2L diesel engines (LH3/LH4) and built with one piece air compressor brackets (P/N 15556206) may be subject to the air compressor mounting bracket bolts loosening. The loosening of the bracket is the result of an interference between a web on the bracket and a boss on the left-hand intake manifold of the engine. Although proper bolt torque was achieved during assembly, the point contact on the web can wear from normal engine vibration which causes loss of clamp load. The loss of clamp load can ultimately result in bolt breakage and the bracket separating from the engine causing a loss of compressor function. Additionally, this separation can sever the compressor oil supply line causing loss of engine oil and severe engine damage.

If this condition should occur, noise from the compressor falling loose may be noted. The low air pressure warning light and buzzer on the instrument panel will activate although the accumulated air pressure in the separate air reservoirs for the front and rear brake systems will not begin to be depleted until brake application. After eight full brake applications the reservoirs' air pressure is so depleted that the rear spring brakes automatically apply. The truck must be repaired before further operation.

It will be necessary to check for interference between the engine left bank intake manifold and air compressor bracket; if necessary grind/ rework the air compressor mounting bracket or replace the mounting bracket if the bracket bolt holes are oblong from the bracket being loose.

VEHICLES INVOLVED:

Involved are 1987-1988 GMC and Chevrolet Medium Duty Model Trucks equipped with 8.2L DDAD engines (LH3/LH4) and one piece air compressor brackets (KYA/K55/K56) built within the following VIN breakpoints:

Model Year Model Plant From Through ---------- --------- ------- -------- -------- 1987 Chevrolet Pontiac HV105486 HV117662 GMC Pontiac HV519639 HV541293

1988 Chevrolet Pontiac JV100021 JV102763 GMC Pontiac JV500005 JV504756

All affected vehicles have been identified by the VIN listing provided to involved Dealers with this bulletin. Any Dealer not receiving a listing was not shipped any of the affected vehicles.

DEALER CAMPAIGN RESPONSIBILITY:

Dealers are to service all vehicles subject to this campaign at no charge to owners, regardless of mileage, age of vehicle, or ownership, from this time forward.

Whenever a vehicle subject to this campaign is taken into your new or used vehicle inventory, or it is in your Dealership for service in the future, you should take the steps necessary to be sure the campaign correction has been made before reselling or releasing the vehicle.

Owners of vehicles recently sold from your new vehicle inventory are to be contacted by the Dealer, and arrangements made to make the required modification according to instructions contained in this bulletin.

CAMPAIGN PROCEDURE:

Refer to Section 4 of the Service Policies and Procedures Manual for the detailed procedure on handling Product Campaigns. Dealers are requested to complete the campaign on all transfers as soon as possible.

OWNER NOTIFICATION:

All owners of record at the time of campaign release are shown on the attached computer listing and have been notified by first class mail from General Motors. The listings provided are for campaign activity only and should not be used for any other purpose.

PARTS INFORMATION:

Parts, if required, should be ordered through regular channels, as follows:

Part Number Description Quantity Per Vehicle ---------- ---------------------- ---------------------- 11513588 Bolt M10 x 1.5 x40mm 1 11508110 Bolt M10 x 1.5 x55mm 2 11503649 Bolt M10 x 1.5 x75mm 1 11504596 Bolt M10 x 1.5 x25mm 1 Pur. Loc. Bolt 3/8-16 x 1-3/4 (280mm) 2 11509161 Washer 11.0 x 21.8 x 2.9 5 15556206 Support Air Compressor 1

PARTS AND LABOUR CLAIM INFORMATION:

Credit for the campaign work performed will be paid upon receipt of a properly completed campaign claim card, RAPID terminal or DCS transmission in accordance with the following:

Repair Code Description Time Allowance ----------- ---------------------- -------------- 1A Inspect bracket for proper .3 clearances and proper bolts; no further action necessary.

2A Inspect bracket for necessary .8 clearance and remove bracket, grind bracket, reinstall bracket, inspect bolts.

3A Inspect bracket - replace bracket 1.0 due to bolt hole(s) elongated.

6A Inspect bracket for necessary .3 clearance; remove and replace bolts as required.

Additional bolts .2

Time allowance includes 0.1 hour for Dealer administrative detail associated with this campaign. Parts credit will be based on Dealer net plus 30% to cover parts handling.

SERVICE INFORMATION:

Listed below are two possible conditions which may create poor bolt durability and the repair recommended.

1. Interference between engine left bank intake manifold and air compressor bracket resulting in false bolt torque reading.

A. Check for proper clearance (.020) feeler gauge between the compressor mounting bracket and the front of the left bank intake manifold with a feeler gauge. See Figure No. 1 (if OK, proceed to Item 2). If the (.020) feeler gauge does not fit, remove the air compressor mounting bracket and grind approximately 3mm or 1/8" from the rib above #10 bolt approximately 2" in length as shown in Figure No. 2. It is important that this rework area be smooth and free of sharp corners. After rework has been completed, install new mounting bolts.

Notice: To help avoid property damage do not grind across the web. Grind the web in an upward or downward motion.

B. If the air compressor bracket has contacted the front of the manifold or if it is loose, check for oblong holes #7, #9, and #10. See Figure No. 3. If the bolt holes are oblong, replace the bracket and install new mounting bolts. If the bracket is replaced, inspection for proper clearances (#lA above) must be repeated.

2. Improper mounting bracket attaching bolts and torque.

A. To determine if the proper bolts were installed, the numbers on the head of the bolt must be inspected. With the exception of Bolt #7 in Figure No. 3, all bolts should be 9.8 grade and 9.8 should be cast on the head of the bolt. Bolt #7 should be 10.9 grade and may be 75mm or 80mm in length, either of which is correct. if an improper bolt is found during inspection, it should be replaced and torqued to the specification listed below:

Notice: To help avoid property damage, use the correct bolt torque for all bolts. Bolt torque specifications for 9.8 grade bolts are different than for 10.9 grade bolts.

B. Associated fasteners and torque specifications are listed below. It is important that the proper grade bolt is used on the mounting bracket installation.

Item No. Qty P/N Description Grade Specification --- ---- -------- --------------------- ----- ----------------- 10 1 11513588 Bolt M10 x 1.5 x 40mm 9.8 45 Nm (35 lbs ft) 9 2 11508110 Bolt M10 x 1.5 x 55mm 9.8 45 Nm (35 lbs ft) 7 1 11503649 Bolt M10 x 1.5 x 75mm 10.9 62 Nm (45 lbs ft) 3 5 11509161 Washer 11.0 x 21.8 x 2.9 (1050 - 1080)

INSTALLATION OF CAMPAIGN IDENTIFICATION LABEL

Clean surface of radiator upper mounting panel and apply a Campaign Identification Label. Make sure the correct campaign number is inserted on the label. This will indicate that the campaign has been completed.

Dear General Motors Customer:

This notice has been sent to inform you that General Motors of Canada, in the interest of customer satisfaction, is conducting a recall campaign that includes your vehicle.

It has been determined that certain 1987-1988 Medium Duty Trucks equipped with 8.2L diesel engines and built with one-piece air compressor brackets may be subject to the air compressor mounting bracket bolts loosening. The loosening of the bolts can ultimately result in bolt breakage and the bracket separating from the engine causing a loss of compressor function. Additionally, this separation can sever the compressor oil supply line causing loss of engine oil and severe engine damage.

If this condition should occur prior to service, noise from the compressor falling loose may be noted. The low air pressure warning light and buzzer on the instrument panel will activate although the accumulated air pressure in the separate air reservoirs for the front and rear brake systems will not begin to be depleted until brake application. Bring your truck to a stop off the road when conditions permit, since after eight full brake applications the reservoirs' air pressure is so depleted that the rear spring brakes automatically apply. Have your truck repaired before further operation.

To correct this condition, the air compressor mounting bracket and bolts will be inspected for looseness and, if necessary, replaced with a new design material. This service will be completed for you at no charge.

Please contact your Dealer to arrange a service date. Instructions for performing this service have been sent to your GM Dealer. The labour time necessary to perform the inspection and/or correction may vary from ten minutes to one hour, depending on the amount of service required for your vehicle. Please ask your Dealer if you wish to know how much additional time will be needed to process your vehicle.

This letter identifies your vehicle. Presentation of this letter to your Dealer will assist their Service personnel in completing the necessary correction to your vehicle in the shortest possible time.

Further assistance, if required, may be obtained from the General Motors Zone Office nearest you. Your vehicle Owner's Manual provides the location and phone number of each respective Zone Office.

We are sorry to cause you this inconvenience; however, we have taken this action in the interest of your continued satisfaction with our products.


Object Number: 88310  Size: LF


Object Number: 75896  Size: FS


Object Number: 86880  Size: FS

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.