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 VISS (Vehicle Information Service System) prior to beginning campaign repairs. [Not all vehicles within the above breakpoints may be involved.]

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.

These dealer listings may contain customer names and addresses obtained from State Motor Vehicle Registration Records. The use of such motor vehicle registration data for any other purpose is a violation of law in several states. Accordingly, you are urged to limit the use of this listing to the follow-up necessary to complete this campaign.

Parts required to complete this campaign are to be obtained from General Motors Service Parts Operations (GMSPO). Please refer to your "involved vehicles listing" prior to ordering requirements. Normal orders should be placed on a DRO = Daily Replenishment Order. An emergency requirement should be ordered on a CSO = Customer Special Order.

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. If additional templates are required, you may order them by calling Dealer Support Materials at 1-888-414-6322 and asking for item number 99078TEMP.

Customers will be notified of this campaign on their vehicles by General Motors (see copy of typical customer letter included with this bulletin - actual divisional letter may vary slightly).

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 customer letter accompanying this bulletin. Campaign follow-up cards should not be used for this purpose, since the customer may not as yet have received the notification letter.

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. When installing the Campaign Identification Label, be sure to pull the tab to allow the adhesion of the clear protective covering. Additional Campaign Identification Labels can be obtained from Dealer Support Materials by calling 1-888-414-6322 (Monday-Friday, 8:00 am to 5:00 pm EST). Ask for Item Number S-1015 when ordering.

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.

Dear <Division(s) Customer:

This notice is sent to inform you of a recall campaign that includes your vehicle.

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, your dealer will install a redesigned air cleaner assembly and duct assembly. This service will be performed for you at no charge .

Please contact your Chevrolet/GMC dealer as soon as possible to arrange a service date and to assure parts availability. Instructions for making this correction have been sent to your dealer. Please ask your dealer if you wish to know how much time will be needed to schedule, process, and repair your vehicle.

If you experience any trouble scheduling your vehicle or you have any questions regarding this recall action, please contact the appropriate Customer Assistance/Relations Center at the number listed below:

The enclosed customer reply card identifies your vehicle. Presentation of this card to your dealer will assist in making the necessary correction in the shortest possible time. If you no longer own this vehicle, please let us know by completing the postage paid reply card and returning it to us.

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

Chevrolet/Pontiac-GMC Divisions

General Motors Corporation

Enclosure