Power Steering - Fluid Filling/Bleeding Precautions

Power Steering - Fluid Filling/Bleeding Precautions
Date: November 26, 2008
Order No.: S-B-46.30/40b
Supersedes: P-B-46.30/40a dated Nov. 27, 2007
Group: 46
Revision History
SUBJECT:
All Passenger and Light Truck Models
Flow Noises from Area of Power Steering Pump and/or Foaming of Power Steering Oil in Reservoir
If you receive customer reports in the above model vehicles of flow noises from the area of the power steering pump, and/or foaming of the power
steering fluid in the reservoir following work carried out on the hydraulic steering system; this may be caused by an improper procedure followed for
filling fluid and bleeding of the hydraulic power steering system.
To remedy, it is absolutely necessary to make sure that the procedure described in the WIS documents is strictly adhered to. In particular, it is
necessary to turn the steering to full lock-to-lock at least 30 times BEFORE STARTING THE ENGINE. If this is not done prior to starting engine,
2000 Mercedes Benz Truck ML 55 AMG (163.174) V8-5.5L (113.981) 343
there is a high risk of air entering the steering system, which is subsequently very difficult to eliminate.
NOTE:
Starting the engine prior to bleeding can cause irreparable damage to the power steering pump and will cause an air cushion to form in the
steering gear which causes noise. Once the air is ingested, the ingested air will only dissipate after driving the vehicle for more than 30 miles.

Refer to the chart for the correct WIS document reference for the proper filling and bleeding procedure of the power steering pump.