CAMPAIGN: AIR IN BRAKE SYSTEM BENDIX MASTER CYLINDER
SUBJECT: AIR IN HYDRAULIC BRAKE SYSTEM
MODELS: 1980-82 C5D042, C6D042, 1983 P6T042
EQUIPPED WITH JE3 & JXP SINGLE HYDRAULIC BRAKE SYSTEM USING A BENDIX MASTER CYLINDER AND A BENDIX HYDROVAC SINGLE DIAPHRAGM BOOSTER.
The National Traffic and Motor Vehicle Safety Act, as amended, provides that each vehicle which is subject to a recall campaign of this type must be adequately repaired within a reasonable time after the owner has tendered it for repair. A failure to adequately repair within 60 days after tender of a vehicle is prima facie evidence of failure to repair within a reasonable time.
If the condition is not adequately repaired within a reasonable time, the owner may be entitled to an identical or reasonably equivalent vehicle at no charge, or to a refund of the purchase price less a reasonable allowance for depreciation.
To avoid having to provide these burdensome solutions, every effort must be made to promptly schedule a service date with each owner and to repair their vehicle as soon as possible. As you will see in reading the attached copy of the letter which is being sent to owners, the owner is being instructed to contact the nearest GMC Zone Office if their dealer does not remedy the condition within five days of the mutually agreed upon service date. If the condition is not remedied within a reasonable time, they are instructed how to contact the National Highway Traffic Safety Administration.
The specific vehicles involved in this campaign have been identified by Vehicle Identification Number Computer Listings. These listings are fumished to all involved dealers with the campaign bulletin.
DEFECT INVOLVED
General Motors has determined that a defect which relates to motor vehicle safety exists in some 1980 through 1983 GMC Medium Duty Trucks equipped with single hydraulic brake systems (RPO's JE3 and JXP). Under certain conditions, trucks equipped with the combination of a Bendix master cylinder and Bendix Hydrovac frame mounted brake booster can draw air into the brake hydraulic system past some of the various seals. The effect of unwanted air in the brake system will result in increased brake pedal travel and reduction or loss of braking ability. A loss of braking ability could result in a vehicle crash without prior warning.
The service procedure to correct this condition is dependent on the type of brake equipment installed on each truck. The procedure depends on whether a truck has an aftermarket brake pressure trapping device parking brake system. A vehicle inspection is necessary to determine the service procedure and replacement parts required for each truck.
Trucks equipped with single hydraulic brake systems were assembled with either a Bendix or a Wagner Master Cylinder. Only trucks having a Bendix Master Cylinder are involved. Trucks with a Wagner Master Cylinder will require no service work other than the vehicle inspection for this campaign.
VEHICLES INVOLVED
Involved are certain 1980-82 C5D042, C6D042, C7D042 and 1983 P6042 trucks within the following VIN breakpoints.
C5D042, C6D042 AND C7D042
Model Year Plant From Through ----- ------- --------- --------- 1980 Pontiac AV557109 EOP 1981 Pontiac SOP EOP 1982 Pontiac SOP EOP
P6T042
Model Year Plant From Through ----- ------- --------- --------- 1983 Pontiac SOP DV515880
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.
GMC 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 fumished 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.
INSPECTION PROCEDURE
All owners of 1980-82 C5D042, C6D042, C7D042, and 1983 P6T042 model trucks will receive notice of this campaign. However, some of these trucks are equipped with Wagner Master Cylinders and are not involved in the campaign. Dealers must inspect each truck to determine whether it has a Bendix (Figure No. 1) or Wagner (Figure No. 2) Master Cylinder.
If the vehicle is equipped with a Wagner Master Cylinder, no further action is necessary.
If the vehicle is equipped with a Bendix Master Cylinder, follow either Service Procedure A or B.
In addition, trucks with Bendix Master Cylinders must be checked to determine if an aftermarket brake pressure trapping device parking brake system has been installed.
SERVICE PROCEDURE
A. Trucks with Bendix master cylinder (Figure No. 1) and without an aftermarket brake pressure trapping device parking brake system.
These trucks will require a new tube and hose assembly between the master cylinder and brake booster (Figure No. 3). See Table 1 for correct part number. It will also be necessary to punch holes in the master cylinder diaphragm to vent the brake system to the atmosphere.
1. Remove tube and hose assembly. Disconnect from master cylinder and from fitting on frame rail. Remove attaching clips.
2. Install new tube and hose assembly (See Table 1). Make sure the arrow on the valve in the new assembly points towards the brake booster. Connect assembly to master cylinder and to fitting on frame rail and attach with clips.
3. Remove the master cylinder cover and take the rubber diaphragm out of the cover. Punch 4 holes of 0.125" - 0.145" diameter in the diaphragm in the locations shown in Figure No. 4. A gasket punch, leather punch, hole punch, or similar tool is suggested for making a clean hole in the diaphragm. Remove the rubber plugs from the holes. Do not allow any debris from the diaphragm to enter the master cylinder. Reposition the diaphragm in the cover and install the cover on the master cylinder.
4. Bleed brake system of air. Refer to Section 5A of the GMC Medium Duty Service Manual. Also refer to Section OB for brake fluid requirements.
5. Road test vehicle to determine if normal brake performance has been restored.
6. Trucks with Bendix master cylinder (Figure No. 1) and with an aftermarket brake trapping device parking brake system.
Trucks with this equipment will require a new Wagner Master Cylinder (P/N 3900146), push rod (P/N 692947), and tube and hose assembly between the master cylinder and brake booster (Figure No. 3). See Table 1 for correct tube and hose assembly part number.
1. Remove old tube and hose assembly by disconnecting from the master cylinder and from fitting on frame rail. Remove attaching clips.
2. Remove Bendix master cylinder. Loosen bolts and remove master cylinder from firewall.
3. From inside of cab under dash, remove master cylinder push rod.
4. Install new push rod (P/N 692947).
5. Fill new Wagner master cylinder (P/N 3900146) with brake fluid. Bench bleed the master cylinder according to the procedure outlined in the appropriate GMC Medium Duty Service Manual, Section 5A. Also refer to Section OB for brake fluid requirements.
6. Install new Wagner master cylinder to firewall. Have an assistant guide the push rod into the master cylinder piston.
7. Install new tube and hose assembly (See Table 1). Make sure the arrow on the valve in the new assembly points towards the brake booster. Connect assembly to master cylinder and to fitting on frame rail and attach with clips.
8. Bleed brake system of air. Refer to Section 5A of the appropriate Medium Duty Service Manual for proper procedure.
9. Adjust master cylinder push rod. Refer to Section 5A of the appropriate Medium Duty Service Manual for proper procedure.
10. Road test vehicle to determine if normal brake performance has been restored.
PARTS INFORMATION
Parts are to be obtained from the Warehousing and Distribution Division of General Motors (WDDGM). To ensure that these parts will be obtained as soon as possible, they should be ordered from WDDGM on a C.I.O. order with no special instruction code, but order on an advise code (2).
Required for all trucks involved in this campaign.
Part Quantity Number Per Vehicle Description ----------- ----------- -------------------------- See Table 1 1 Brake Tube & Hose Assembly
TUBE AND HOSE ASSEMBLY USAGE
TUBE AND HOSE PART NUMBER
Cab Type Model Year Use With Use With Wagner Master Bendix Master Cylinder Cylinder ------------ ----------- ------------ ------------- 1980 15516050 15516054 Regular Conventional 1981 15516052 15516055 1982
Top Kick 1980 High Cab 1981 15516935 15516934 (EPG) 1982
Forward 1981 Control 1982 ------- 15516056 (BNQ) 1983
Cowl 1982 15516052 15516055 (BNR)
In addition, the following parts are required on trucks equipped with a Bendix Master Cylinder and an aftermarket brake pressure trapping device parking brake system.
Part Quantity Number Per Vehicle Description -------- ----------- ----------------------- 3900146 1 Wagner Master Cylinder
692947 1 Master Cylinder Push Rod
WARRANTY INFORMATION
Dealers should submit an accurately filled out Warranty Repair Order on each vehicle completed under this campaign.
A. Trucks with Wagner Master Cylinder with or without an aftermarket brake pressure trapping device parking brake system.
1980-1981 MODELS
Labor Operation *Time Trouble Operation Description Allowance Code --------- --------------------------------- --------- ---- V210000 Inspect vehicle for type 0.2 Hour 96 of brake master cylinder. Equipped with Wagner Master Cylinder, no further action required.
1982 - 1983 MODELS
Labor Operation *Time Trouble Operation Description Allowance Code --------- --------------------------------- --------- ---- V2100 Inspect vehicle for type 0.2 Hour 96 of brake master cylinder. Equipped with Wagner Master Cylinder, no further action required.
B. Trucks with Bendix Master Cylinder and without an aftermarket brake pressure trapping device parking brake system.
1980 - 1981 MODELS
Labor Operation *Time Trouble Operation Description Allowance Code --------- --------------------------------- --------- ---- V210100 Inspect vehicle. Replace tube and 0.6 Hour 96 hose assembly. Punch hole in master cylinder diaphragm. Includes bleed air from brake system.
1982 - 1983 MODELS
Labor Operation *Time Trouble Operation Description Allowance Code --------- --------------------------------- --------- ---- V2101 Inspect vehicle. Replace tube and 0.6 Hour 96 hose assembly. Punch hole in master cylinder diaphragm. Includes bleed air from brake system.
C. Trucks with Bendix Master Cylinder and with aftermarket brake pressure trapping device parking brake system.
1980 - 1981 MODELS
Labor Operation *Time Trouble Operation Description Allowance Code --------- --------------------------------- --------- ---- V210200 Inspect vehicle. Replace master 0.9 Hour 96 cylinder, push rod and hose assembly. Includes bleed air from brake system.
1982 - 1983 MODELS
Labor Operation *Time Trouble Operation Description Allowance Code --------- --------------------------------- --------- ---- V2102 Inspect vehicle. Replace master 0.9 Hour 96 cylinder, push rod and hose assembly. Includes bleed air from brake system.
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.
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.
