Steering - Power Steering Pump Noise
NO.: 64-28DATE: 11-5-2007
MODEL/MODEL YR:
S40 (2004.5-), V50 (2005-), C70 (2006-), C30 (2007-)
SUBJECT:
Power Steering Pump Noise
REFERENCE:
VIDA
Description
There may be cases when excessive noise is heard from the EHPAS (Electro-hydraulic Power Assist Steering) pump. In many cases, the pump itself is not the root cause of the noise.
This TNN is designed to assist the technician in performing the proper diagnosis and repair before the pump or any other component is replaced.
Service
If a customer complains about a noisy EHPAS pump while sitting inside the vehicle:
1. First check the front brake dust shield for any touching condition.
2. Check if the EHPAS pump is in contact with the A/C dryer:
- Remove the black plastic wheel arch liner at the right front wheel.
- Inspect if the two parts are in contact with each other (see photo shown above).
- If the two parts are in contact, correct the position of the A/C dryer.
- If the noise is gone, reinstall wheel arch liner and return the car to the customer.
- If there is good clearance between the two parts, continue with the steps below.
3. Inspect the underside of the EHPAS pump for dents or damage on the metal housing. If a dent or damage is found, replace the EHPAS pump.
4. If no dents or damages are found, check the routing of the delivery lines between the EHPAS pump and the steering rack. Ensure that the lines are not touching anything along their routing. Correct any touching condition which is found.
5. If no touching condition is found or if the noise is still present, there can be tension in the EHPAS pump mounting brackets. Release the tension according to steps 5a through 5d below.
5a. Remove front bumper
Remove front bumper and the protecting casing according to VIDA.
5b. Loosen connections
Loosen the two A/C receiver screws at A, the EHPAS pump mounting screws at B, and the delivery line connection (circled in 2nd photo).
Note!
There is no need to completely unscrew the delivery line connection or the screws.
5c. Jiggle the pump & reassemble
Jiggle the pump to release any tension in the connections and bushings.
Re-tighten all connections strictly in this order:
^ first tighten the delivery line connection to 22 lb.-ft. (30 Nm)
^ then tighten the two A/C receiver screws (A)
^ lastly tighten the three EHPAS pump fastening screws (B).
5d. Reinstall front bumper
Reinstall front bumper and protecting casing according to VIDA.
6. If the noise is still present:
^ Flush the entire power steering system with new fresh oil (flushing instructions below).
^ Once the system has been flushed, fill up with new power steering oil.
^ Test drive the car to determine if the noise is still present.
7. If the noise is still present after flushing the power steering with new oil, replace the EHPAS pump according to VIDA.
Flushing instructions:
^ Park the car for a while before the procedure to reduce the oil temperature in the system.
^ Disconnect the return hose from the EHPAS pump, and put a clean empty container of at least 2 quarts capacity (2 liters) under the return hose.
^ Start the engine and begin to collect the oil in the container. Add new power steering oil to the EHPAS pump at the same time old oil is drained from the return hose.
Caution!
Power steering oil may be hot.
^ When a total amount of approximately 2 quarts (2 liters) of power steering oil has been collected in the container, turn off the engine and reinstall the return hose.
Note!
Used power steering oil should be disposed of in an environmentally safe manner.
WARRANTY CLAIM INFORMATION