BLEEDING AIR FROM RACK AND PINION POWER STEERING SYSTEMS
BLEEDING AIR FROM RACK AND PINION POWER STEERING SYSTEM
(Section No. 3B) ----------------
When to bleed:
o After any component replacement
o After disconnecting fluid line
o In case of steering system noise
Why bleed?
o To prevent pump damage
o To ensure proper system operation
o To stop steering system noise
Before Bleeding: Inspect steering system. Check and correct as needed:
Hoses must not touch any other part of the vehicle.
o Steering system noise could be caused by hose touching the frame, body or engine.
All hose connections must be tight.
o Loose connections might not leak but could allow air into the system.
How To Bleed:
1. Switch ignition off.
2. Turn the steering wheel full left.
3. Fill fluid reservoir to "FULL COLD" level. Leave cap off.
4. Raise the front wheels off of the ground.
5. With an assistant checking fluid level and condition, turn steering wheel lock-to-lock at least 20 times. Engine remains off.
o On systems with long return lines or fluid coolers, turn steering wheel lock-to-lock at least 40 times.
o Trapped air may cause fluid to overflow. Thoroughly clean any spilled fluid to allow for leak check.
o Keep fluid level at "FULL COLD".
6. While turning wheel, check fluid constantly.
o No bubbles are allowed.
o If there is any sign of bubbles, recheck connections. Repeat step 5.
7. Start engine. With engine idling, maintain fluid level. Reinstall cap.
8. Return wheels to center. Lower front wheels to ground.
9. Keep engine running for 2 minutes.
10. Turn steering wheel in both directions.
Verify:
------ Smooth power assist
Noiseless operation
Proper fluid level
No system leaks
Proper fluid condition
o No bubbles, no foam, no discoloration.
11. If all above checks are verified, procedure is complete.
12. If any problem remains, see "Special Conditions".
Special Conditions
Fluid
o Foam or bubbles in fluid.
Fluid must be completely free of bubbles. In step 5, be alert to periodic bubbles that could indicate a loose connection or leaky 0-ring seal.
o Discolored Fluid (Milky, opaque, or light tan color)
Switch ignition off. Wait two minutes. Recheck hose connections. Repeat steps 7-10. If condition still exists, replace 0-ring seals and hose clamps. Fill system and repeat bleed procedure.
Noise
o Pump whine or groan
With engine running, recheck hoses for possible contact with frame body or engine.
If no contact is found, follow either method below to cool down fluid and repressurize system.
Method 1: Normal Cool Down
Switch engine off. Wait for system to cool. Install reservoir cap.
Method 2: Partial Fluid Replacement
Switch engine off. Use a suction device to remove fluid from reservoir. Refill with cool clean fluid. Install reservoir cap.
After either method of cooling, start engine and allow engine to come up to normal operating temperature. If noise persists, remove and replace power steering pump. Repeat bleed procedure following pump replacement.
Power Steering Fluid
Use only clean, new power steering fluid. Fluid should be:
GM #1050017 - 32 ounce #12345866 - 16 ounce #12345867 - 32 ounce
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.
