Can anyone point me towards instructions for replacing the power steering pump on an '01 ML320? The dealer wants $800 to replace it. I read that the job is straight forward and can be done for about $250, including a few specialized tools. Any "tricky" spots to watch out for? Other input?

 

It is extremely rare that these pumps go bad. The problem is usually with a leaky O-ring at the reservoir which causes noise.

Explain what your problem is.

 

The steering is difficult to turn when engine is idling (about 700 RPM). Once RPM's reach about 1000, the steering works normally.

The dealer said the pump cannot be opened and just has to be replaced--no mention of an O-ring.

 

You never mentioned it so I have to ask. Have you checked the fluid level?

Are there any noises while turning at 700 RPM's?

 

Good question. Fluid level is good, confirmed by both me and the dealer. Minor whining when turning wheel at idle.

 

To save you money, try this first.

Order a new reservoir from M/B, approx. $20 and a new O-ring, but don't order the pump as yet.

Remove the one bolt (female torx) securing the reservoir to the pump and then remove the C-clip..

Install new reservoir and fill the reservoir with fluid. Do not start the engine and perform the bleeding procedure as outlined in the pdf. Raise the two front wheels off the ground and turn the key to pos. #2 and while someone slowly turns the steering wheel from one end to the other. You look into the reservoir while the person is turn and when the air bubbles stop the procedure is over.

If this does not correct the condition then replace the P/S and the only thing you will have to do is remove the reservoir and transfer it to the pump, but remember that the bleeding procedure still applies.

 

Thank you for the reply and great auxiliary info--very Helpful! I will try replacing the o-ring. Thanks, again!