CAMPAIGN: MASTER CYLINDER BRAKE PROPORTIONER

MODELS AFFECTED: 1983 CENTURYS, SKYLARKS AND SKYHAWKS

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 sixty (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 an appointment with each owner and to repair the vehicle as soon as possible. As you will see in reading the attached copy of the letter which is being sent to owners, the owners are being instructed to contact the nearest Buick Zone Office if their dealer does not remedy the condition within five days of the agreed service date. If the condition is not remedied within a reasonable time, the owners are instructed on how to contact the National Highway Traffic Safety Administration.

DEFECT INVOLVED

General Motors has determined that a defect which relates to motor vehicle safety exists on some 1983 Centurys, Skylarks and Skyhawks. The brake proportioner valves used on some of these vehicles may break and separate from the master cylinder. This would result in a brake fluid leak and a partial loss of the brake system. These vehicles are equipped with a dual braking system; part of the system will still work and allow the vehicle to be stopped, but over a greater distance. Partial loss of the brake system at a time when minimum stopping distance is required could result in a vehicle crash without prior warning.

DEALER ACTION

To prevent the possibility of this condition from occurring on vehicles involved, dealers are to inspect to determine if a vehicle has suspect proportioner valves as instructed in the Technical Procedure of this bulletin. All suspect valves are to be replaced.

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.

VEHICLES INVOLVED

Vehicles involved are certain 1983 Centurys, Skylarks and Skyhawks within the following serial numbers:

Model Assembly Plant Beginng Up to and Including

Century Doraville DD408333 DD445796 Century Oklahoma City D6403491 D6412752 Skyhawk Leeds DK411090 DK433771 Skylark Willow Run DW425910 DW458221 Skylark Tarrytown DT403790 DT407043

DEALER MATERIAL

If your dealership has vehicles involved in this campaign, you will receive the following items:

- List of all vehicles involved in their campaign shipped to your dealership.

- One (1) campaign identification label per vehicle involved.

Involved vehicles have been identified by Vehicle Identification Number Computer Listings. Computer listings contain the complete Vehicle Identification Number, Owner Names and Address Data, and are furnished to the involved dealers with the campaign bulletin. Owner name and address data furnished will enable dealers to follow-up with owners involved in this campaign.

These listings 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 for the follow-up necessary to complete this campaign.

TRANSFER OF VEHICLE

If a vehicle has been transferred or sold to another location, please forward Campaign Identification Label and vehicle information for this vehicle to your Buick Zone Office for handling with the proper dealer.

CHANGE OF OWNER INFORMATION

Dealers are to use the Dealer Communication System (D.C.S ) to provide Buick Motor Division with subsequent Buick Owner Information. By reporting a change of owner name or address of a vehicle in Campaign status over the D.C.S., the need to sent in an S-866 Form for that vehicle is eliminated. Terminal input instructions are covered in the D.C.S. Manual under Section 9, Page 9-J01A and B.

OWNER NOTIFICATION

Owners of vehicles involved in this campaign will be notified by Buick Motor Division (see copy of owner letter included with this Bulletin).

PARTS INFORMATION

The parts for this campaign are to be obtained from WDDGM as required. Refer to chart to obtain correct valve for a vehicle.

PART NUMBER & I.D. CODE ON VALVE BODY)

Model Usage Front Location Rear Location 10mm 13mm

Century *With JA2 (Hvy Duty 18009966(FJ) 18009967 (RJ) Brake System

Century **With JA1 (Lt. Duty 18008570(FK) 18008571 (RK) Brake System) Skylark ALL 18008570(FK) 18008571 (RK) Skyhawk ALL 18009966(FJ) 18009967 (RJ)

*JA2 = Models with 2.5L engine and GVMR over 1784 KG, and models With 3.0L snd 4.3L diesel engines

**JA1 = Models with 2.5L engine and GVWR under 1784 KG (GVWR can be found on the certification label located inside the driver's door.)

To ensure this part will be obtained as soon as possible, it should be ordered on a C.I.O. order with no special instruction code, but order on an advise code (2).

TECHNICAL PROCEDURE

PART I

Inspection of Proportioner Valves

1. Open vehicle hood and cover left-front fender.

2. It may be necessary to clean the ends of the front and rear brake proportioner valves located in the master cylinder for inspection. If this is required, wipe valves clean using brake fluid. Do not use a solvent to clean the valves, as it could enter the small notches (vents) and cause damage to the internal seals of the valves.

3. Inspect the front and rear proportioner valves to determine if either one or both of the valves need to be replaced. Refer to Figure 1. Use a magnifying glass to identify te valves. Proportioner valves from three different sources were used interchangeably; therefore, both front and rear valves will not require replacement in all cases.

4. Replace all proportioner valves, as instructed in PART II of this procedure, that are of design shown in View A of Figure 1. If the valve identification cannot be accuratel detemined, or there is a question on identification, valve(s) should be replaced.

Special care should be taken to insure that specified torque values are used when installing new proportioner valves.

5. If valves are the design shown in View 8 or View C of Figure 1, no further action is required except to install a campaign identification label as instructed in PART III of this procedure.

PART 11

Replacement of Proportioner Valve

1. Refer to Parts Information section of this bulletin to obtain correct part number proportioner valve(s) for vehicle.

2. Place material under proportioner valve connections to protect under hood parts from brake fluid.

3. Refer to Figure 2 for valve replacement procedure.

4. Bleed master cylinder and proportioner valve connections as follows:

a. If the car is equipped with power brakes, remove the vacuum reserve by applying the brakes several times.

b. After installing new valve(s), reconnect all removed brake pipe connectors.

c. Fill the master cylinder reservoirs with brake fluid and keep at least one-half full of fluid during the bleeding operation.

d. Remove left front pipe connector. Refer to Figure 3. When brake fluid begins to flow from left front master cylinder port, reconnect left front brake pipe and tighten to specified torque.

e. Slowly apply brake pedal until firm.

f. Loosen left front brake pipe connector to purge air. Retighten connector and slowly release brake pedal. Wait 15 seconds.

g. Repeat (e) and (f) until all air is purged. (IMPORTANT:COMPLETE (g) BEFORE ATTEMPTING (h) AND (i).

h. Repeat (e) and now loosen right front brake pipe connector to purge air. When brake fluid begins to flow from connector, retighten connector to specified torque and slowly release brake pedal. Wait 15 seconds. Refer to Figure 3.

i. Repeat (h) until all air is purged.

5. Check the brake pedal for "sponginess" and brake warning light for indication of unbalanced pressure. Repeat bleeding operation to correct. Do not move car until a firm brake pedal is obtained.

6. Tighten all tube nuts to specified torque and correct any leaks, if required.

7. Fill master cylinder.

8. Install a campaign identification label.

PART III

Installation of Campaign Identification Label

After the above has been completed, install a campaign identification label as follows:

Each label provides a space to include the campaign number, the five (5) digit Dealer Code of the dealer performing the campaign service, and the date vehicle was campaigned. This information may be inserted with a typewriter or ballpoint pen. When installing label, clean the surface of the radiator upper mounting panel and apply the campaign label where it is readily visible.

DISPOSITION OF REPLACED PARTS

Replaced parts must be held for disposition by Buick contact personnel. Each replaced part must have a claim tag attached, showing the repair order and the VIN of the vehicle from which it was removed.

WARRANTY INFORMATION

Dealers are to submit each campaigned vehicle as a separate case on the one-line Warranty Document Form S-764. Dealers submitting warranty claims by teletype terminal are to transmit campaign completions as a separate case also. List the one applicable labor operation.

SUBLET PART FAILED PARTS FAILURE LABOR LABOR OTHER DEALER OPER COUNT PART NO. ALLOW. CODE OP. NO. HOURS HOURS MTL.TWG

Inspect hrake proportioner valves 96 V1820 .2 hr *.1 hr. Inspect valves and replace one valve 1 96 V1821 .3 hr *.1 hr. $1.02

Inspect valves and replace two valves 2 96 V1822 .4 hr *.1 hr. $1.02

*.1 hours for administration

**List part number of replaced part

***List current dealer price plus 30% of replaced parts

**** Allowance for 1/2 pint brake fluid.

To assure accurate records of all transactions on this Campaign, it is recommended that Campaign repairs for each vehicle be listed on a separate repair order. Other repairs performed to the vehicle may be listed on the same repair order, and warranty cases other than Campaigns way be listed on the same warranty document.

Zone authorization is not required.

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.