I just finished up the TB, water pump, crank seal and cam seal install. When I started the car all seemed well but for a loud clattering from the power steering pump. I assumed that I perhaps over tightened the belt, so I loosened the belt and restarted. The noise diminished somewhat, but when I turned the wheel to back out of the garage a loud "groan" ensued and I noticed a trail of atf on the floor.
Upon inspection I discovered the atf was actually pouring from the top of the reservoir and the reservoir was completely filled. I am thinking that in moving the alternator/ ps console towards the radiator in order to remove one of the covers that I may have pulled the hose loose that enters the rear of the pump. I can, with the aid of a flashlight, see that the hose is still attached but it looks like maybe it is not all the way on the pump. Anyone know if this were the case if it would result in the symptoms described? Or does anyone have any other ideas as to what is wrong? I would like some advise before tearing things apart.
My car is an 86.5. TIA. T.T.


My first guess is that you have a leaking hose connection that is allowing the pump to suck air. This entrains air in the fluid, increasing the volume, and causing the reservoir to overflow. I would check all of the hose connections between the pump and reservoir.

Wally Plumley
928 Specialists


Power steering pump rebuild.pdf


Is the power steering pump done if growls when cold?


I've searched all the power steering + leak + hose + pump + noise + groaning threads... Mine seems to behaving and slightly leaking like others with leaks in the low pressure regions of the system.

Recently found a small to medium size damp puddle/spot of red fluid beneath the alternator, after sitting for about 5 days of cold weather. The cooling air hose for the alternator was saturated and a red drop clinging to the bottom of the bottom of the alternator.

I made more of a mess starting the car and turning it lock to lock, thinking I was working some air out of the system. Lots of loud groaning. Thought I was successful when it stopped making the noise, but this appears to be a false correlation. Then noticed a bit more fluid underneath and in the area of the original fluid reservoir, hoses, cam gear cover and distributor, etc. More dripping off the alternator and cooling hose. All the same kinds of things I read about in the archives.

But I've noticed something interesting. If I let the car warm up completely I get zero symptoms. Pump makes minimal noise at or near locks, and no leaks.

My hypothesis is this: The supply line has one of the common leak points described by others. When cold the hose shrinks, opening up the leak gap, and it sucks air straight to the pump, causing the groaning if I'm turning the wheel. By not turning the wheel there is no demand on the system draw fluid, and thus air, into the circuit. I'm also guessing this has something to do with no leaking during this warm up time. After everything is toasty under the hood, the hoses have expanded, closing the leak gaps enough that the system functions relatively normal. Perhaps lower viscosity of the fluid is helping as well, as I'm seeing seeing the dampness around the reservoir cap, indicating the filter is dirty.

Fluid level has dropped surprisingly little. In fact, the fluid level has never dropped below the cold line on the dip stick.

Finally getting to the title question. If the pump doesn't make much or any noise when the leaking stops after the fluid is warm, is the pump likely ok, just complaining those times it had air in it?

I've got a rebuilt pump, new supply line (the one with all the bends in it), and a new reservoir. Given what I've been reading about rapidly failing rebuilt pumps (I don't know the source of this rebuilt pump) I'd prefer the easier job of replacing thing reservoir and low pressure hoses, per Dwayne's tutorial.

So, based on collective experience, should I just do the hoses and see if all is quiet and dry afterward, or will I be going back in again to replace the pump very soon?

first fix the leaks,
inspect the rack boots for fluid ,
if they have fluid in them then a new rebuilt rack may be in your future.

Usually replacement of the reservoir and the factory curved hose and the short feed line will fix the leak.
drop the alternator to get access to the rear of the pump,  tighten the hose fittings on the pump as they may be loose, make sure the belt is tight

Next drain the rack remove the banjos and turn the wheels back and forth the old oil will come out refit using 4 new sealing washers .
Refill with new Dextron 4 ATF turn the wheel back and forth a few time dont hold it against the lock as it can cause the rack end seals to leak 

+1, what Mrmerlin said-- fix the leaks first, before worrying about the pump. Also replace the reservoir & filter while you are in there.

Leaks work both ways, fluid out and air in. A tiny leak on the suction side won't let much fluid out, there is no pressure. But it can let a lot of air in, especially when the suction is high-- which happens with cold, thick fluid and a nasty, clogged filter in the reservoir. And when air gets into the fluid it makes a very expensive-sounding groaning noise in the pump.
Jim & Sue Corenman
These pumps get very unhappy (read noisy) if they are starved of input fluid - just try clamping the input line flat and see. I have heard of internal delamination of the hoses can cause blockages.
jp 83 Euro S AT 54k

An old mechanic's trick for locating a leak might come in handy.

It can be difficult to see where oil or fluid is leaking. Clean the area, and blow a little corn starch onto the area. This will leave a thin film of white power covering the area. Leaks will be instantly apparent. The powder is totally non-corrosive, and easily removed. Available very cheaply in the grocery section, but your SO may have a box in the cabinet already.
Wally Plumley

I looked through the PET as well, and found there are actually three PS pumps listed:

928.347.431.05 for '84 and earlier,
928.347.089.00 for '85 to '90, and
928.347.089.01 for '91 and later.

And I could only find repair kits listed for the first two pumps.

Apparently the earliest pump is made by ZF, and the latest is the 100 Bar Vickers pump. Not sure about the middle pump, but I assume its made by Vickers and is 75 Bar. This would mean the Rennbay rebuild kit only works on '84 and earlier.

I also found the Porsche rebuild kits on Pelican - one for '84 and earlier, and the other they claim is for "85 and up". So either the PET is wrong or Pelican is wrong about the later kit working on the 100 Bar pumps.

Tom D.


There are 2 different pumps used in the 928. Starting MY `90 until MY '95 A 10 MPa pump is used (928.347.089.01, AX or BX). Before then the pump was a 8 MPa (part number 928.347.089.00)