CAMPAIGN: 6.2L DIESEL ENGINE OIL FILLER CAP REPLACE

1983-1984 G-VANS AND P MODEL LIGHT DUTY TRUCKS EQUIPPED WITH A 6.2L DIESEL ENGINE (RPO LH6/LL4)

General Motors has determined that some 1983- 1984 G-Vans and P Model Light Duty Trucks equipped with a 6.2L diesel engine (RPO LH6/LL4) may experience crankcase depression regulator valve (CDR) restriction or plugging.

The crankcase depression regulator valve on the 6.2L diesel maintains a negative pressure in the crankcase by drawing air out of the oil filler tube. Water vapors and vent gases present in the crankcase condense in the vent hose. This condensate (water-oil mixture) collects at the low point of the ventilation system, which is the inlet tube of the CDR valve. In extremely cold ambients this condensate freezes and restricts or plugs the ventila- tion system. This allows the crankcase pressure to increase forcing oil out of the engine causing a major engine failure requiring replacement of the engine.

To prevent the possibility of this condition occurring during below freezing temperatures, a new design oil filler cap, with a pressure relief valve, should be installed.

Since an oil filler cap can be easily installed, and to reduce owner inconvenience, new oil caps will be sent directly to owners of record. Owners may install the new cap or they may ask a dealer to do the service. Dealer service is to be done at no charge to owners.

VEHICLES INVOLVED

Involved are all 1983 and 1984 G-Vans and P Model Light Duty Trucks equipped with a 6.2L diesel engine (RPO LH6/LL4).

If your dealership has vehicles involved in this Campaign, you will receive a VIN listing, and a new oil filler cap for each vehicle for which there is no owner of record. If a vehicle has been recently delivered, and the owner's name is not on your VIN listing, please contact the owner to have the oil filler cap changed. It is your responsibility to see that the oil filler caps are changed on recently sold vehicles.

The specific vehicles involved in this campaign have been identified by Vehicle Identification Number Computer listings. These listings are furnished to all involved dealers with the campaign bulletin.

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.

If no owner's name and address were available to GMC Truck at the time of campaign initiation, the dealer will determine the owner's name and address from the dealership sales records. Please provide this information directly on the second copy of the listing next to the applicable VIN, so that our records may be updated and the appropriate notification mailed to the owner. This second copy should then be submitted to the address listed below in the previously supplied yellow campaign envelopes.

G M C Truck General Motors Corporation 101 Union Street Plymouth, Michigan 48170

OWNER NOTIFICATION

Owners will be notified of this campaign on their vehicles by GMC Truck (see copy of Owner Letter included with this bulletin). A listing of owner names and addresses has been furnished to the involved dealers to enable dealers to follow up with owners involved in this campaign. This listing may contain owner 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 this campaign.

SERVICE PROCEDURE

Install a new oil filler cap, Part No. 25060118 (identified as shown in Figure No. 1), on each involved vehicle.

PARTS INFORMATION

Parts required to complete this campaign will be mailed to the owners of record and to involved dealers by GMC Truck. Additional campaign parts can be obtained by contacting your Zone Office. Do not order parts from WDDGM.

To complete vehicles in your inventory, the $2.38 amount identified in the "Parts Allowance" column below represents 30% of dealer net for parts that were fumished by GMC Truck. This amount is to be placed in the Net Item Amount column of the claim and use type Code "M".

Part Parts Quatity Number Description Allowance Per Vehicle ------ ----------- --------- ----------- 25060118 Oil Filler Cap $2.38 1

WARRANTY INFORMATION

Dealers should submit an accurately filled out Warranty Repair Order on each vehide completed under this campaign.

Labor Operation Time Trouble Number Description Allowance Code ------ ----------- --------- ---- V2460 Replace Oil Filler 0.2HR. 96 Cap

*For dealer to receive Administration Time Allowance associated with this Campaign, add 0.1 hour to the Labor Operation Time Allowance.

CAMPAIGN IDENTIFICATION LABEL

Each vehicle modified 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 five (5) digit Dealer Code of the dealer performing the campaign service. This information may be inserted with a typewriter or ballpoint 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 for periodic servicing by the owner.

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

ADMINISTRATIVE PROCEDURE

Procedures covering this campaign are outlined in Section V of your dealership's "GMC Truck Claims Processing Manual" issued April, 1983.

Dear GMC Truck Owner:

General Motors has determined that some 1983-1984 G-Vans and P-Model Light Duty Trucks equipped with a 6.2L diesel engine (RPO LH6/LL4) may experience a rapid loss of engine oil as a result of crankcase pressure due to condensate freezing and blocking the crankcase ventilation line.

To prevent the possibility of this condition occurring on your truck during below freezing temperatures, a new design oil filler cap with a pressure relief valve, should be installed.

A new cap is enclosed for your convenience. Rather than asking you to return to your GMC Truck dealer, it is believed you might wish to install the new cap yourself. Just remove the old one, dispose of it, and install the new one in its place. If you wish to return your vehicle to your dealer for this change, they will be pleased to assist at no charge to you.

If you install the new cap, or if you have sold or traded your vehicle, please let us know by completing the enclosed postage paid owner reply card and returning it to us. This will assist us in assuring all affected vehicles have been corrected and will eliminate the need to contact you with follow-up notifications. If you no longer own the vehicle, you may dispose of the new cap.

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

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.