Shortly after purchasing my 85 635, it started making an awful screeching noise at the power steering pump. It usually wouldn't make a noise unless I was turning or pulling into a parking space, but it got to where it would make the noise at idle or slightly above. When I looked to diagnose the problem, I found that the belt was slipping on the pulley, and purchased a second pump from a parts yard for a rebuild. Both pumps are good, nether one needed rebuilding, so I ended up tightening the belt, and the problem went away for about a month. The problem is now back, and I'm wondering if the slippage could be due to the fact that the pulley is made up of two plates that are bolted together. Perhaps it is being vibrated loose? Thoughts anyone?

Thanks,
Alex

Did you clear the pump filter when installing the second pump? Check on the fluid to see if it should just be replaced. I had the same issue on an E23, and the fluid was full of metal debris. If the filter is clogged then it starts to choke the pump slowly so it makes that terrible noise.

-Jeff

I'll have to look into the fluid. It's the bronze-colored canister on the... passenger side...??? I remember the color, but not the location. It mostly stays parked at school and hasn't given me grief enough to open the hood, so it's been a little while. I do remember opening up the canister and noticing that the fluid was red, but I didn't think to take a peek at the filter. Is the filter in the canister, or is that just the reservoir? I'm also assuming that if the filter is clogged, the fluid will have a dark gray tint to it.

Thanks,
Alex

Ok I have the same problem on my 85 635, the thing that I did was, putting new liquid, changing the filter, changing the hose, and changeing the belt. Nothing works. Now I'm planning to put new pump and I hope it'll work.

I'm thinking that if the fluid change doesn't work, perhaps I will weld together the plates that compose the pulley. It seems strange that they are separate entities rather than a single piece.

if its the belt, like in my case, i just took the belt off. it saves you money and the hassle of trying to fix the problem. the only down is no power steering, but hey, my arms look a hell of a lot better now with the work out =P If you can manage without p/s and dont mind putting a little extra muscle when turning into a parking spot, id just pull the belt off

on 83-89 cars, if you remove the power steering belt, you will have no power brakes as well

and i think no abs

I found that the belt was slipping on the pulley ...... so I ended up tightening the belt, and the problem went away for about a month. The problem is now back, and I'm wondering if the slippage could be due to the fact that the pulley is made up of two plates that are bolted together. Perhaps it is being vibrated loose? Thoughts anyone?

If the belt has been slipping, it is probably glazed, clean the pulleys and replace the belt after you have changed the hydraulic fluid (Dexron ATF) and filter.


I'll have to look into the fluid. It's the bronze-colored canister on the... passenger side...??? I remember the color, but not the location. It mostly stays parked at school and hasn't given me grief enough to open the hood, so it's been a little while. I do remember opening up the canister and noticing that the fluid was red, but I didn't think to take a peek at the filter. Is the filter in the canister, or is that just the reservoir? I'm also assuming that if the filter is clogged, the fluid will have a dark gray tint to it.

The hydraulic reservoir is next to the fuse box, here is a link on changing the filter and flushing it.

http://bigcoupe.com/phpBB2/viewtopic.php?t=2314&highlight=flush+hydraulic

The sound is from the pump cavitating, either the pump can't pull enough fluid from the reservoir, or there is air being sucked in from some where. If the pump is OK (internal clearances and seals OK), then carefully check out the intake hose and fittings. Check the hose clamps and crush washers first, but I've heard that if the hose seems to be "sweating" ATF fluid out, then air can get in.