Customer Satisfaction 99078-Engine Air Induction Contamination

General Motors has decided that certain 1997-1999 Chevrolet and GMC medium duty T-series trucks equipped with diesel engines may exhibit engine air induction contamination. Dirt ingestion can occur through joints on the air induction system that do not have a tight fit. This could compromise the integrity of the air induction system.

To correct this condition, dealers are to install a redesigned air cleaner assembly and duct assembly.

Involved are certain 1997-99 Chevrolet and GMC medium duty T-series trucks equipped with diesel engines and built within the following VIN breakpoints:

Important: Dealers should confirm vehicle eligibility through DCS Screen 445 or your VIN listing prior to beginning campaign repairs. [Not all vehicles within the above breakpoints may be involved.] Only affected VINs will be paid.

Involved vehicles have been identified by Vehicle Identification Number. Computer listings containing the complete Vehicle Identification Number, customer name and address data have been prepared, and are being furnished to involved dealers with the campaign bulletin. The customer name and address data furnished will enable dealers to follow-up with customers involved in this campaign. Any dealer not receiving a computer listing with the campaign bulletin has no involved vehicles currently assigned.

Important: Check the engine code before ordering parts. The engine code is the 8th digit in the VIN.

* -- Do not order the template from GMSPO. An initial supply has been included with the bulletin for affected dealers. If additional templates are required, make a copy of the template inside this bulletin.

Registered letters will be sent to known owners of record located within areas covered by the U.S. National Traffic and Motor Vehicle Safety Act, as amended. For owners outside these areas, the attached suggested dealer letter is recommended and should be sent by dealers.

All unsold new vehicles in dealers' possession and subject to this campaign MUST be held and inspected/repaired per the service procedure of this campaign bulletin BEFORE customers take possession of these vehicles.

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

Customers who have recently purchased vehicles sold from your vehicle inventory, and for which there is no customer information indicated on the dealer listing, are to be contacted by the dealer. Arrangements are to be made to make the required correction according to the instructions contained in this bulletin. This could be done by mailing to such customers a copy of the appropriate customer letter accompanying this bulletin.

In summary, whenever a vehicle subject to this campaign enters your vehicle inventory, or is in your dealership for service in the future, please take the steps necessary to be sure the campaign correction has been made before selling or releasing the vehicle.

1. Take proper actions to ensure safety and tilt the cab forward. Follow the procedure located near the cab release on the back of the cab.
2. Loosen the clamp and remove the boot from the top of the air cleaner assembly inlet.
3. Loosen both hose-type clamps at the rear of the air cleaner.
4. Remove the battery cover and disconnect the batteries.
5. Remove the outboard battery.
6. Remove the four (4) retainers that are holding the air cleaner assembly support to the battery box and the frame bracket.
7. Remove the air cleaner assembly and the support assembly from the vehicle.

•	For engine codes "2" and "J," discard the air cleaner assembly and the support assembly.

•	For engine codes "3" and "C," remove the air cleaner assembly from the support bracket. Discard the air cleaner assembly. Keep the bracket as it will be reused.

8. Remove the air intake restriction indicator from the aluminum air cleaner duct.
9. Loosen the hose-type clamp at the forward end of the aluminum air duct, where the rubber 180-degree elbow attaches to the air duct.
10. Remove the three (3) attaching bolts that are holding the aluminum air cleaner outlet duct in place. Remove the duct assembly and discard after removing the hose clamps.
11. Install the aluminum air cleaner outlet duct to the U-shaped duct and loosely install the retainers. The new duct for the engine code "C," P/N 15746347 may have one or two attaching holes, depending on its date of manufacture. Use only the bottom one if there are two holes.
12. Reinstall the air intake restriction indicator.

Tighten
Tighten the brass fitting to 12.5 N·m (111 lb in).

Tighten
Tighten the plastic filter to 1.7 N·m (15 lb in).

13. For engine codes "2" and "J," position the template to the front air cleaner frame support and drill two (2) new 14 mm (9/16 inch) holes in the frame support to receive the new air cleaner support bracket.
14. Install the new air cleaner support bracket to the new air cleaner assembly. For VINs "3" and "C," it would be the bracket removed in Step 7.

Tighten
Tighten the bracket to 23 N·m (17 lb ft).

15. Install the clamps to the air cleaner outlet duct. Place the duct to the air cleaner.
16. Install the assembly to the vehicle.
17. Tighten the fasteners holding the air cleaner bracket to the battery box and the frame support.

Tighten
Tighten the fasteners to 70 N·m (52 lb ft).

18. Tighten the fasteners holding the aluminum air cleaner outlet duct to the cab support and the bracket.

Tighten
Tighten the fasteners to 70 N·m (52 lb ft).

19. Properly position the three (3) hose-type clamps.

Tighten
Tighten the clamps to 3 N·m (27 lb in).

20. Install the battery and hold down. Reconnect the battery cables.
21. Install the battery box cover.
22. Install the boot on the top of the air cleaner inlet tube.

Tighten
Tighten the clamp to 3 N·m (27 lb in).

23. Lower the cab.
24. Inspect for the proper alignment of the boot, on the top of the air cleaner inlet tube, to the cab-mounted intake tube.
25. Install the GM Campaign Identification Label.

Each vehicle corrected in accordance with the instructions outlined in this Product Campaign Bulletin will require a "Campaign Identification Label". Each label provides a space to include the campaign number and the five (5) digit dealer code of the dealer performing the campaign service. This information may be inserted with a typewriter or a ball point pen.

Each "Campaign Identification Label" is to be located on the radiator core support in an area which will be visible when the vehicle is brought in by the customer for periodic servicing. Additional Campaign Identification Labels can be obtained from your Regional Marketing Office.

Apply the "Campaign Identification Label" only on a clean, dry surface.

Submit a Product Campaign Claim with the information indicated below.

Refer to the General Motors Corporation Claims Processing Manual for details on Product Campaign Claim Submission.

Suggested Dealer Letter

General Motors has decided that certain 1997-99 Chevrolet and GMC medium duty T-series trucks equipped with diesel engines may exhibit engine air induction contamination. Dirt ingestion can occur through joints on the air induction system that do not have a tight fit. This could compromise the integrity of the air induction system.

To correct this condition, we will install a redesigned air cleaner assembly and duct assembly.

This service will be performed for you at no charge.

Please contact us as soon as possible to arrange a service date.

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

GMODC

General Motors Corporation

Dear General Motors Customer:

General Motors has decided that certain 1997-1999 Chevrolet and GMC Medium Duty T-Series Trucks equipped with diesel engines may exhibit engine air induction contamination. Dirt ingestion can occur through joints on the air induction system that do not have a tight fit. This could compromise the integrity of the air induction system.

To correct this condition, your GM dealer will install a redesigned air cleaner assembly and cut assembly.

This service will be provided for you at no charge.

Please contact your GM dealer as soon as possible to arrange a service date.

The card included with letter identifies your vehicle. Presentation of this card to your dealer will assist their Service Personnel in completing the necessary correction to your vehicle in the shortest possible time.

Your General Motors dealer is best equipped to obtain parts and provide service to ensure your vehicle is corrected as promptly as possible. However, if you take your vehicle to your dealer on the agreed service date and they do not remedy this condition on that date or within five days, we recommend you contact the GMODC Customer Assistance Center by telephone (905)644-4112. They will assist you and the dealer through our local GMODC office in getting your vehicle corrected.

After contacting your dealer and the Customer Assistance Center, if you are still not satisfied we have done our best to remedy this condition without charge within a reasonable time, you may wish to write to the Administrator, National Highway Traffic Safety Administration, 400 Seventh Street, S.W., Washington, D.C. 20590 or call 1-800-424-9393.

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

GMODC

General Motors Corporation