POWERMASTER BRAKE PUMP REPRIMING PROCEDURE

VEHICLES AFFECTED: 1985 and 1986 Models Equipped With Powermaster Brake Assembly

A problem may be encountered in bleeding the Powermaster if for any reason the pump has not been properly filled with brake fluid. If after any service or new installation the pump does not circulate fluid after the motor has run for 20 seconds, it may be necessary to reprime the pump. In order to reprime the system, the following steps should be followed.

1. Turn off the ignition.

2. Apply the brake pedal with medium pressure 10-15 times with ignition off to discharge pressure from the accumulator.

3. Clean and remove reservoir cover.

4. Disconnect the booster tube and nut assembly from the casting boss at pump outlet. Refer to illustration.

5. Wait for brake fluid to gravity bleed from the disconnected end of the tubing.

6. When brake fluid begins to flow, reconnect the tube and torque to 17 N.m. (13 lb. ft.).

7. Check the fluid level in the reservoir and add new brake fluid if needed. Reinstall the reservoir cover.

8. Turn on the ignition. The pump should properly circulate the fluid to the accumulator. The fluid level on the inboard side of the reservoir should diminish if the pump is working properly.

9. Continue with service manual bleed and fill procedure.

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.