C 1500 Truck 2WD V8-305 5.0L VIN F 4-bbl (1985)
Hydraulic Brake Booster: Service and Repair
Hydro-Boost Unit Bleeding Procedure
Whenever the booster is removed and reinstalled. the steering system should be bled as outlined below:
NOTICE: Power steering fluid and brake fluid cannot be mixed. If brake seals contact steering fluid or steering seals contact brake fluid, seal damage
will result.
1. Fill power steering pump reservoir to proper level and let fluid remain undisturbed for at least two minutes.
2. Start engine and run momentarily.
3. Add fluid, if necessary.
4. Repeat above procedure until fluid level remains constant after running engine.
5. Raise front end of vehicle so that wheels are off the ground.
6. Turn the wheels (off ground) right and left, lightly contacting stops.
7. Add fluid if necessary.
8. Lower the vehicle.
9. Start engine and depress the brake pedal several times while rotating the steering wheel from stop to stop.
10. Turn engine off and then pump brake pedal 4-5 times to deplete accumulator pressure.
11. Check fluid level and refill as required.
12. If fluid is extremely foamy, allow vehicle to stand a few minutes with engine off and repeat above procedure.
a. Check oil level, filling to proper level if necessary, following operations 1 through 10. This step and Step "b" are extremely important as low
oil level and/or air in the oil are the most frequent causes of objectionable pump noises.
b. Check the presence of air in the oil. Air will show up as milky appearing oil. If air is present, attempt to bleed system as described in
0perations 1 through 10. If it becomes obvious that the pump will not bleed after a few trials, proceed as outlined under Power Steering System
Test procedure in the Steering Section.
13. The presence of trapped air in the system will cause the fluid level in the pump to rise when the engine is turned off. Continue to bleed the system
until this condition no longer occurs.
