Tech - Pwr Strng Sys Noise Concerns (Replace PSS Hose, Enlarge Sys. Restrictor)

Some customers may comment on a rushing or grinding sound from the power steering pump. Some customers may also refer to the sound as a low-pitched moan. This sound may be audible from outside of the vehicle and/or be heard inside of the vehicle only when the steering wheel is being turned. This condition may be intermittent due to temperature and idle speed variations.

2.4L 4 cylinder engine

Vehicles equipped with the 2.4L engine may exhibit the above condition due to a low power steering fluid level. These vehicles were built with an in-line fluid restrictor that, under cold weather conditions, may create excessive pressure on the power steering return line/hose assembly. This may result in a slow, intermittent cold temperature power steering fluid leak at the hose to line crimp.

3.4L 6 cylinder engine

Vehicles equipped with the 3.4L engine may exhibit the above condition due to an improper fluid restrictor. These vehicles may have been built with an under-sized orifice in the restrictor that may intermittently cause excessive noise.

2.4L 4 cylinder engine

If the vehicle was built before November 8, 1998, inspect the power steering line/hose assembly for evidence of leaking. This may be a very slow or intermittent leak. The fluid will remain at the point of the leak for some time, creating a damp appearance. If any sign of a leak is present, replace the hose with a new hose assembly, P/N 26068108. Remove and discard the fluid restrictor from the power steering system.

Use the following procedure in order to correct the above condition for the 2.4L 4 cylinder engine:

1. Drain the power steering reservoir using a suction pump.
2. Remove the spring clamp from the power steering return hose at the reservoir.
3. Remove the hose from the reservoir nipple.

Important: Verify the presence of the restrictor. Vehicles built after approximately November 8, 1998 may not have a power steering restrictor. If a restrictor is not present, disregard this bulletin and refer to the 1999 N Car Service Manual for diagnostic information. See the footnote under the Warranty Information section of this bulletin.

4. Remove and discard the metal fluid restrictor.

In some cases, the restrictor may lodge itself in the hose. It is not necessary to dislodge the restrictor. If a leak is present, it will be discarded with the assembly. If the hose assembly is being reused, you can usually shake the restrictor loose. Avoid using tools which may score or cause damage to the restrictor or the inner diameter of the hose.

If the hose is being replaced, continue with Step 5. If the hose is being reused, go to Step 16.

5. Raise and suitably support the vehicle.
6. Cut the tie strap securing the power steering hoses.
7. Remove the 10 mm nut and the 10 mm bolt that secure the line assemblies.
8. Remove the power steering pressure line from the steering gear in order to gain access to the return line.



9. Remove the power steering return line at the steering gear.
10. Remove the power steering return hose/line assembly from the vehicle. Discard the assembly.
11. Install the new power steering return hose line assembly (5), P/N 26068108, to the vehicle.
12. Install the power steering return line at the steering gear.
13. Install the power steering pressure line to the steering gear.
14. Install the 10 mm nut and the 10 mm bolt that secure the line assemblies.
15. Lower the vehicle.
16. Install the hose to the reservoir nipple. Secure the hose with a new clamp, P/N 22527587, or the equivalent.
17. Secure the lines with a tie strap.
18. Fill the power steering system. Refer to Checking and Adding Power Steering Fluid in the Power Steering sub-section of the 1999 N Car Service Manual.
19. Bleed the power steering system. Refer to Bleeding Power Steering System in the Power Steering System sub-section of the 1999 N Car Service Manual.
20. Inspect for any leaks.

3.4L 6 cylinder engine

If the vehicle was built before February 1999, inspect the size of the restrictor orifice. If necessary, enlarge the power steering fluid restrictor orifice by drilling.

Use the following procedure in order to correct the above condition for the 3.4L 6 cylinder engine.

1. Drain the power steering reservoir using a suction pump.



2. Remove the clamp (1) from the power steering return line.
3. Remove the power steering return hose from the pump nipple.

Important: Some vehicles built after November 8, 1998 may have been built with the proper restrictor. Refer to Step 5 to verify the restrictor size. All vehicles built after February 1999 are equipped with the enlarged restrictor. If the correct restrictor is already fitted, the customer concern is not related to this bulletin. Please refer to the Power Steering System sub-section of the 1999 N Car Service Manual for additional information on diagnosing power steering system noises. See the footnote under the Warranty Information section of this bulletin.




4. Remove the restrictor.

The restrictor is metal and should be seated into the inlet of the power steering reservoir. Occasionally, the restrictor will lodge itself into the power steering return hose. It will be visible in the end of the hose and can usually be shaken loose. Avoid using tools which may score or cause damage to the restrictor or the inner diameter of the hose.

5. Test the restrictor for proper size by attempting to pass a 9/64 in (#27) drill bit through the orifice. If the drill bit does not fit through the hole, the orifice needs to be enlarged.

Notice: Only use enough force to retain the restrictor. Use of additional force may damage the restrictor.

6. Wrap the restrictor in rubberized tape or a suitable substitute to protect the outside edge of the restrictor. Use a vise to secure the restrictor for drilling.

Caution: To avoid personal injury, wear approved safety glasses when drilling and using compressed air.

Notice: Extreme care must be taken to ensure that all metal shavings are removed from the restrictor. Failure to remove all of the drilling debris may result in increased steering effort and eventual possible damage to the power steering pump.

7. Using a 9/64 in (#27) drill bit, re-drill the hole through the restrictor. Visually inspect that the hole is centered and true. Flush the restrictor with fluid and blow dry with compressed air to assure that all the metal shavings have been removed.
8. Install the restrictor to the reservoir return inlet nipple.
9. Install the return hose to the inlet. Secure the hose with a new clamp, P/N 22527587, or the equivalent.
10. Fill the power steering system. Refer to Checking and Adding Power Steering Fluid in the Power Steering System sub-section of the 1999 N Car ServiceManual.
11. Bleed the power steering system. Refer to Bleeding Power Steering System in the Power Steering System sub-section of the 1999 N Car Service Manual.

Parts are currently available from GMSPO.

For vehicles repaired under warranty, use: