ddieringer

Hello,

I have a 1987 944 n/a, 250k miles, which I've owned for nearly 20 years. I'm the second owner, so I have a pretty solid history with this particular car.

I rebuilt my leaky power steering pump a few days ago using the "944 Online" rebuild kit. It was easy and straighforward. Bleeding was simple. The pump pulled fresh fluid from the reservoir with ease. No leaks, not even at the copper crush washers. I used proper Dexron III ATF (non-synthetic). It is red and unclouded in the fluid reservoir.

It worked great for the first test drive. Upon returning home and backing into my driveway, the pump started to groan (like it had when the fluid got low).

I've tried re-bleeding it (raising the wheels off the ground and turning the steering wheel). I've thoroughly cleaned and degreased everything so I can check for new leaks.

Supply hose... Ok
Hose clamps on suppy hose... Ok
High pressure hose... Ok
Under the tie rod boots/baffles... Ok
Cooling loop... Ok
Return hose... Ok
Hose clamps on return hose... Ok

I confirmed that all hose clamps are tight, as well as the bolts holding the pump together.

I did not replace the reservoir. It appears to be in good condition, despite its age. (i haven't replaced it in my 20 years with the car).

After the car is off for a few hours, the ps pump is dead slient for the first 30 seconds (after starting the car, of course).
If the car is off for only a few minutes, the ps pump is silent for about 10 seconds.

I'm not sure what to make of all that. The pump groan makes me think air is getting into the system before the pump, but I can't detect from where that would be. No fluid is leaking out, so I don't know how air would get in. Plus, the fluid in the reservoir is red and not cloudy.

I'll happily replace additional parts, though I'd like some advice as to how to diagnose what else needs to be replaced.

I would really enjoy hearing anecdotes from other people who have experienced this problem and solved it.

I'm not interested in converting to a manual steering rack/setup.

Thank you

Pin It

Did you add more fluid to the reservoir each time after turning the wheels lock to lock?

Also, I've never raised the wheels off the ground to bleed the pump, but perhaps others can chime in. Maybe the PS system needs to be loaded with the weigh of the car while bleeding?

Pin It

Also, are your sure your belt is tight? IMO the proper PS belt tension always feels like it is overly tightened with the finger test.

ddieringer

Thank you for the suggestions. :-)

Fluid was properly added while bleeding and the belt is tight. The reservoir is full, and the fluid is red without froth or discoloration.

After initial rebuild and bleeding, the ps pump ran quietly. It ran quietly during the post-repair test drive. (I think I did alright with the bleeding procedure.)

The ps pump began groaning again only after returning home from the post-repair test drive. It runs without groaning for 10-30 seconds after initially starting the car. I can detect no additional leaks - not under the tie rod boots/baffles, and not under the thick rubber sleeve that normally protects the high-pressure line from the pump. I cannot eliminate the groan with continued bleeding (wheels on or off the ground).

I believe there is another fault in the system. Before I simply purchase all the parts and replace them, I'd like to be a bit more targeted.

Pin It

I would double check the belt tension before replacing parts or rebuilding the pump again. You want it *tight*. Make sure to loosen the pivot bolt before adjusting the tensioner rod and then tighten the pivot bolt down very snugly. I did my PS pump earlier this year and noticed the same groaning after the car was warmed up. I made the belt much tighter and the groan went away.

ddieringer

I'm certain the belt is tight and that the pivot bolt was properly loosened and tightened, etc. I have worked on this car for ~20 years now. I pretty sure I've tried all the simple stuff already. :-)

My groan-after-rebuild problem appears to have nothing to do with engine/fluid temp, since it goes from silent to groaning within 10-30 seconds after starting regardless of whether the engine is warm. The ps pump is turning without groaning during the 10-30 seconds of silent operation, so I doubt additional belt tension is the solution in my case (and I've already tried that).

It is ponderous, though, why your ps pump would groan upon warm up until the belt was adjusted. However, I could imagine belt slip being influenced by ambient and under-hood temps that naturally change as the car warms up. I do hope your anecdote helps someone in the future, though.

jderimig

Still try tightening the belt a little more. I had the same problem. If your belt is slipping a little, 10-30 seconds of running will heat it up, make it longer which makes it looser.

thomasmryan

the filter is part of the reservoir. the ZF replacement is 25 buck or so.

75ohm

Do you have assisted steering when this is happening or does it feel like a manual rack?

If so, it's possible your rebuild is allowing the inner seal to get pulled into the pump...

ddieringer

It feels like a manual rack when this is happening. No assist whatsoever. Driveway speeds require much steering input.

It's not really difficult to pull the pump apart again. I'll see what the inner seal is doing. Would this mean my reassembly was sub-optimal, allowing the inner seal to not seat properly?

75ohm

Let us know first... and we can go from there...

Aivar88

search similar topics, theres a thread when someone had new internal seal sucked inside a small hole in the pump.

Hack

So I think you are implying that the filter could have debris in it, causing a restriction in fluid flow. Makes sense to me that a restriction like that could cause the groaning.

Seems worth $25 to check out to me.

ddieringer

Well, it appears my inner seal was blocking the small holes (see pictures).

Before I blindly reassamble and hope for the best, what should I have done differently in the first place, and what should I do differently now? I don't think the seal was upside down - it only seems to want to go in comfortably with the flat side down. it lays tightly in its channel like that, at least (the third pic below).


Freshly cracked-open groaning-after-rebuild pump


Holes blocked by the inner seal


Seal re-seated

Pin It

Wow. You might consider starting over with the Rennbay kit which I found to have much better fitment than is apparent in your pics.