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Tim Mohr
Tim Mohr, ASE MASTER TECH
Category: Mercedes
Satisfied Customers: 15154
Experience:  30 YRS EXPERIENCE, FOREIGN AND DOMESTIC, GAS AND DEISEL
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I am having trouble getting the air out of the power

Customer Question

I am having trouble getting the air out of the power steering.
JA: When was the fluid last checked? Have you heard any whining noises while turning the wheel?
Customer: I changed the pump and fluid over a month ago. Just recently changed the reservoir and supply hose. I still have the groaning noises. I see tiny air bubbles in the fluid.
JA: What is the model/year of your Mercedes?
Customer: 2007 E63
JA: Are you fixing your vehicle yourself? What have you tried so far?
Customer: yes
JA: Anything else you want the mechanic to know before I connect you?
Customer: no
Submitted: 2 months ago.
Category: Mercedes
Expert:  Tim Mohr replied 2 months ago.

Hi, my name is ***** ***** ar difficult to get bleed out, but the easiest and most efficient way is with a vacuum bleeder, but if you dont have one, anther option is to jack up the front, and fill the resevoir, then manually turn the tires from stop to stop, with the engne OFF, do not use the steering wheel, grab one of the front tires and manually move from left to right, do this about 4 times, then let it sit for a half hour and repeat, after doing this 2 times, you have all the air out of the system,Tim

Expert:  Tim Mohr replied 2 months ago.

Please dont forget to rate me, so I can get credit for helping,Thanks,Tim

Customer: replied 2 months ago.
I do have a vacuum pump, but it did not work. I have not tried moving just the tires. I can try that tonight. I have been trying to correct the issue for over a month now. I've tried everything that WIS manual says to do. No luck. Very frustrated. I had little success with the vacuum pump. I can hear the air is in the rack. It seems the air is trapped there. The WIS manual says if you start the engine before getting all the air out by turning the steering wheel lock to lock about 30 times or so, you may not get all the air out unless you perform an alternate method. The manual does not say what the alternate method is. Do you know what the alternate method might be?
Expert:  Tim Mohr replied 2 months ago.

the above procedure is the alternate method, do not use the steering wheel to turn the wheels, turn them by hand from the outside, this will remove the air in the entire system, if this does not work, then you have a defective pump,Tim

Customer: replied 2 months ago.
Hi Tim,
So far your procedure has not worked. I can still hear air squishing around in the rack. There is larger amount of air at the stops. The power steering pump has been changed twice, so I have ruled that out as being the problem. Do you have any other suggestions?
Expert:  Tim Mohr replied 2 months ago.

if the air is coming back, then the only other thing it can be is a bad rack and pinion, nothing else,Tim

Customer: replied 2 months ago.
Tim,
Please give me a couple of days. It seems that your method made a difference, but I still have air coming out. It appears to be an improvement, but I won't know if it is definitely fixed until I give it a little more time.
Customer: replied 2 months ago.
I changed the o-rings for the 2 lines going into the rack. Still not fixed. For 2 months now, l have not been able to get all the air out. I'm starting to believe it could be the rack as you said. The rack does not leak any fluid, but I've read it could take on air. My biggest fear is that I replace it and it still doesn't fix the problem. Is there anyway to determine that the rack is definitely bad?
Expert:  Tim Mohr replied 2 months ago.

It is the only thing left, if the seals in the rack go bad, it can let air in, but you wont see any leak,Tim

Customer: replied 2 months ago.
When about the high pressure hose, return hose and the lines going to the cooler?
Expert:  Tim Mohr replied 2 months ago.

if air was being sucked at one of these lines, it would also be leaking, as they are all pressure lines,Tim