Is there any cure for a whining power steering pump....mine has gotten
progressively noisier as the weather here in KY has cooled...also I can feel it
functioning jerkily....it seems fine after a few miles & everything is heated
up.....it has plenty of fluid, I did notice it being foamy though...can these
animals be over-hauled...or is a new pump my only out????
'87 S4 5spd
Having gone through the same thing there are a number of things to look into. At first I thought I would have to rebuild the PS pump but it turned out to be a combination of other things.
1. Check the rack seal on the right side. The rack may be leaking from other places, but the right side is the most common. Pull back the boot if it is still in one piece and see if there is any power steering fluid there.
Mine came pouring out - almost a cup. The culprit is the seal in the end of the rack. They can be obtained locally from places that sell seals and while I removed my entire rack, the change can probably be made while the rack is on the car.
To change the seal remove the lower protection plate and push aside the boot. The end of the tie rod can be unscrewed from the rack with a couple of large wrenches - I think 27 and 32 MM but I could be off.
The end of the rack is held into place by a threaded ring. I used a brass punch to start the ring turning. It is locked into place by a couple of chisel marks. Once free the ring spins out reasonably well. You might want to clean things up first as getting dirt into the rack is probably not such a good idea. I found brake clean works well.
Once the ring is loose the end of the rack housing slides off. There is one O ring and one seal inside. In front of the seal is a plastic washer that is worth replacing as well. The seal has a number that can be cross referenced.
A leak in the seal will cause air pockets in the rack resulting in some of the jump you are feeling in the wheel.
2. The supply and return hose on the reservoir have a tendency to leak. For some reason the supply hose is prone to getting porous. You can tighten the clamp but it will still leak. Short of replacing the hose cut off about a
1/2 inch on the reservoir side and use some blue silicon to seal the connection. Some of the jumping you are feeling is a result of PS fluid from this hose dripping on the belt and causing it to slip. Brake clean is ideal for cleaning off a wet belt.
If you just fix the reservoir hose you may still get a little jump if the rack is still leaking. If you do not want to search around for the rack seals and plastic bushing then there is a rack rebuild kit on eBay. Overall you are probably looking at on the low side $20 in parts and about two hours in time to do the entire job. Afterwards the steering will be smooth and responsive even when the car is idling in tight turns. I could not believe to difference this make to my car.
While you are in there check the tie rod inner joints. If the ball on the tie rod does not offer some resistance then it is time to replace the tie rods as well. Loose tie rods will cause some shake in the steering wheel when hitting bumps.
Dan the Pod Guy