Whine in power steering pump after replacing SLS pressure hose - W124
 

1988 300TE, 230,000 miles
Replaced leaking SLS pressure hose with a Gates 6G2 steel braided hydraulic hose from an industrial supply store. I drained the hydraulic fluid by suction from the tank and replaced with Febi hydraulic fluid (2 liters). Bled the hydraulic system. Replaced the power steering filter, flushed and refilled with power steering fluid. The SLS system works (raising and lowering). This is a W124 with the SLS/PWR steering combo platter pump. The whine starts when you start the engine and increases with engine speed. There is no change in sound when you turn left or right. The sound can only be heard inside the vehicle, not under the hood. Is this the wrong type hose for this car? When I took the old hose off nothing came out of it (plastic doohickies). Can anyone offer some infor into this? Thanks.

If that's the case why do you think it's the power steering pump?

A dumb question, but was your stereo turned on at the time? I had a guy swear something was whining inside his car and it turned out to be a badly grounded stereo picking up alternator noise. He only noticed it when the power was turned on, but the volume all the way down. When music was playing, it drowned out the alternator noise. One day he just turned the volume down and left the stereo on, and that's when his problem "started"

I fully assume that this is not the case in your situation, but I just thought I'd point that out anyway.

-tp

I don't think its the power steering pump. I think its the hose.
It wasn't making the noise until I replaced the hose.
Thanks.

The radio was not on, but thanks for pointing that out.

I think the original hose has small plastic tubes inside it to quiet the noise.

My new hose is doing the same thing. I just read a few other threads that point to the plastic inserts of the old hose as being invaluable for the noise reduction.

The original hose was well covered in a plastic foam jacket and supported at two points with grommets (all of which was brittle and now gone). I presumed the wrap was for heat as it's on the portion of the hose that runs past the block and exhaust.

I will endeavor to find a similar hose wrap and new grommets and see if the noise level changes.

-CTH