Steering - Power Steering Diagnostic Tips

Steering - Power Steering Diagnostic Tips
Date: March 2008
Order No.: P-B-46.25/37a
Supercedes: P-B-46.25/37
2000 Mercedes Benz Truck ML 55 AMG (163.174) V8-5.5L (113.981) 333
Group: 46
Revision History
Revision Date Purpose
a 03/03/08 Additional Models Added
- 07/13/06 Initial issue
SUBJECT:
MODELS 129, 140, 163, 164, 170, 171, 199, 202, 203, 204, 208, 209, 210, 211, 215, 216, 219, 220, 221, 230, 251, 463
Processing of Steering System Complaints
For any Power Steering Complaint, please always refer to the latest version of the EDAC Diagnostic Guide found on Star TekInfo. It includes
all the latest bulletins repair information.
1.) Complaints about noise from the vicinity of the hydraulic steering system:
Many complaints about noise from the steering system, particularly during the colder seasons, can be caused by the fluid level in the power
steering pump reservoir being too low, without the system having a leak.
Depending on the reservoir, small shortages are sufficient to cause the pump to take in air or foaming fluid, which then produces noises. As a
result, if a complaint is received about noise when the engine is running, such as hissing, gushing or humming from the vicinity of the pump,
first check the fluid level in the reservoir.
If the fill level is only slightly lower i.e. just under the relevant specified marking, correct this before performing any other work on the
steering system and reassess the vehicle.
To prevent this type of effect, we recommend always filling the fluid level in the power steering pump reservoir to "Maximum" for the
corresponding temperature, particularly during winter inspections or other relevant vehicle checks.
2.) Information on replacing the power steering pump in the case of steering system leaks:
The power steering pump does not have to be replaced if the hydraulic steering system is leaking and the vehicle was driven a short distance
without power steering fluid in the reservoir. Driving without power steering fluid for up to 30 miles does not damage the power steering
pump. Without fluid, it is not placed under any stress (pressure buildup) compared to normal operation.
The residual fluid in the pump is sufficient to provide an adequate lubricating film. After repairing the steering system, perform a function and
noise check on the steering system, including the power steering pump. In the case of leaks, the location of the leak is to be indicated with a
wax pen if the complete component, such as steering racks and pumps, are replaced.
3.) General information on warranty return parts:
It is crucial to attach a detailed description of the damage profile to be able to specifically investigate the damaged part and initiate remedial
measures if necessary. We urge dealers to fully utilize the warranty text field to provide as much information as possible on the reasons for the
replacement of specific components, particularly power steering racks and pumps.
The reason for replacement of a steering rack or pump must be included on all warranty claims.
Warranty claim text will be compared to the subject vehicle's Warranty history. If it becomes apparent in the review that an existing repair

method (i.e. fluid level corrected, a repair kit, etc.) has not been utilized prior to replacing a power steering rack or pump this claim will be