Whine Noise from Power Steering (P/S) System During Vehicle Start-up at Low Ambient Temperatures (Flush/Bleed P/S System, Change P/S Fluid)

Some customers may comment on whine noise from the P/S system during vehicle start-up at low ambient temperatures (approximately -12°C (10°F) and lower).

In cold ambient temperatures, the P/S fluid thickens in the same manner as any other petroleum based oil. Because of the length of the P/S lines, the thickened oil causes the pump to be noisy during cold start-up.

Flush and Bleed the P/S system. Replace the P/S fluid with Cold Climate power steering fluid. Follow the service procedure listed below in order to flush and bleed the P/S system.

Flushing the Power Steering System

1. Turn off the engine.
2. Open the hood.
3. Install fender covers.
4. Raise the front end of the vehicle off the ground until the tires and wheels turn freely. Refer to the Lifting and Jacking the Vehicle procedure in the General Information subsection of the Service Manual.
5. Place a large container under the fluid return hose in order to collect the draining fluid.
6. Remove the fluid return hose at the P/S pump inlet underneath the reservoir by removing the clamp with a pair of pliers.
7. Drain the P/S fluid from the reservoir.
8. Plug the reservoir return hose inlet connection on the P/S pump reservoir.

Important: 

•	Do not run the engine without the P/S fluid level at FULL COLD.

•	This step will require 4 L (4 qt) of Cold Climate power steering fluid.

9. Fill the P/S reservoir to the FULL COLD mark with Cold Climate power steering fluid, P/N 12345866 (in Canada, use P/N 10953484) 0 .5 L (16 ounce), or P/N 12345867 (in Canada, use P/N 10953471) 1.0 L (32 ounce).
10. Run the engine at idle while an assistant maintains the fluid level at FULL COLD in the reservoir using 4 L (4 qt) Cold Climate power steering fluid.

Notice: Do not hold the wheel against the stops while flushing the system. holding the steering wheel against wheel stops will cause high system pressure, overheating, and damage to the pump and/or gear.

11. Turn the steering wheel from stop to stop.
12. Continue draining until all of the old fluid is cleared from the P/S system.
13. Turn off the engine.
14. Remove the plug from the pump reservoir inlet connection.
15. Install the fluid return hose to the pump reservoir.
16. Fill the P/S reservoir to the FULL COLD mark with Cold Climate power steering fluid.

Bleeding the Power Steering System

Notice: If the power steering system has been serviced, an accurate fluid level reading cannot be obtained unless air is bled from the steering system. The air in the fluid may cause pump cavitation noise and may cause pump damage over a period of time.

1. Attach the J 43485 to the J 35555 or equivalent.
2. Place the J 43485 on or in the pump reservoir filler neck.
3. Apply a vacuum of 68  kPa (20 in Hg) maximum.
4. Wait 5 minutes.
5. Remove the J 43485 and the J 35555.
6. Verify the fluid level.
7. Reinstall the pump reservoir cap.
8. Start the engine. Allow the engine to idle.
9. Turn off the engine.
10. Verify the fluid level.
11. Start the engine. Allow the engine to idle.

Notice: Do not hold the wheel against the stops while bleeding the system. holding the steering wheel against wheel stops will cause high system pressure, overheating, and damage to the pump and/or gear.

12. Turn the steering wheel 180 - 360 degrees in both directions five times.
13. Switch the ignition OFF.
14. Verify the fluid level.
15. Repeat steps 1-14.
16. Reinstall the pump reservoir cap.
17. Clean any spilled fluid.
18. Remove the fender covers.
19. Close the hood.
20. Lower the vehicle.
21. Test the vehicle to verify that the steering functions normally and is free from noise.

Parts are currently available from GMSPO.

For vehicles repaired under warranty, use: