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Super mechanic
Super mechanic, ASE Certified Technician
Category: Mercedes
Satisfied Customers: 17212
Experience:  ASE Master, 30+ years exp. troubleshooting, diag. electrical, collision
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A new power steering unit was installed on my GL4 50 and it

Customer Question

A new power steering unit was installed on my GL4 50 and it has a knocking noise along with some vibration and I was toldthere was air in line causing this and would eventually go away
Submitted: 1 year ago.
Category: Mercedes
Expert:  Super mechanic replied 1 year ago.

Hello and welcome. My name is ***** ***** you for visiting the site, I will be happy to assist you today.

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Are you sure it's not from the bearing and housing of the upper steering shaft (firewall pivot point) or the steering coupling?

Customer: replied 1 year ago.
The power steering unit was leaking at the rear seal, and I was told we needed to replace the unit. I chose to go with a new unit rather than a rebuild. After installation of the unit, which also included replacement of the re savour there was this knocking sound, and the technician told me it was air in the lines and it would eventually go away. That was about a week ago and it is still vibrating and making a knocking noise. This noise did not exist with the original P/S unit.
Expert:  Super mechanic replied 1 year ago.

I see, thanks. There were a couple of factory service bulletins for steering noises. A thumping sound doesn't normally come from the pump, (gushing or whining may). Also, after a week of driving the air should all be out.

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Here is one of the bulletins.

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If you receive customer reports in the above model vehicles of groaning or dull, heavy cracking noises from the steering shaft area when turning the steering wheel / moving off or braking, this may be emanating from the bearing and housing of the upper steering shaft (firewall pivot point) or the steering coupling (lower steering shaft).

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I can get the instructions for it and put it in a PDF file, (it is rather large) and send it to your email address for as little as possible.

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You will just have to accept the additional service offer and ENTER your email address in the “ENTER CONTACT INFO” section so that I can see it, Thanks

Customer: replied 1 year ago.
I have decided to wait a week of driving, and if the noise is still there have the mechanic take a further look. I don't think trying to solve this on the internet is for me. Thanks.
Expert:  Super mechanic replied 1 year ago.

You’re welcome and please come again, anytime, thanks and Happy Holidays.

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Please don’t forget to rate the answer, **** THAT IS THE ONLY WAY I GET PAID **** if you need any more on it, I will be here.

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