Technical Procedure
PART IInspection 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) of valves 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 the valves. Proportioner valves from three different sources were used interchangeably; therefore, both front and rear valves will not require replacement in all cases.
FIGURE 1 - IDENTIFICATION FOR BRAKE PROPORTIONER VALVES FOR CAMPAIGN 83-C-8:
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 accurately determined, 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 B 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.
FIGURE 1 - IDENTIFICATION FOR BRAKE PROPORTIONER VALVES FOR CAMPAIGN 83-C-8:
FIGURE 1A - SUSPECT PROPORTIONER VALVE:
Suspect proportioner valves which are installed on cars to be campaigned can be identified as described in Figure 1, View A. In addition, the suspect valves will have six-character Julian Date Codes stamped in the valve body from FJ, RJ, FK or RK 2305 through 3035. See Figure 1A, below.
^ Valves with different machine marks than Figure 1, View A, are okay.
^ Valves with the same machine marks as View A, but date codes lower than 2305 or higher than 3035, are okay.
^ Valves received in service parts or campaign parts packages, regardless of their machine marks, are okay.
^ Valves on cars with serial numbers lower or higher than the serial number breakpoints.
PART II
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.
FIGURE 2 - BRAKE PROPORTIONER INSTALLATION:
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.
9. Repeat (e) and (f) until all air is purged. IMPORTANT:
COMPLETE (g) BEFORE ATTEMPTING (h) AND (i).
FIGURE 3 - MASTER CYLINDER BRAKE PIPES IDENTIFICATION:
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:
CAMPAIGN LABEL:
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.