Power steering pump- no pressure

[brian in buddina]

My 1988 944ś has reverted to a non power steering model. The power steering just stopped working. 

Belt is good, lots of fluid, no 'major' leaks.There are signs of previous leakage from a previous owner.

Drained most of the fluid looking for foreign debris. No chunks but some small fine particles.

I pressure tested the pump & got zero pressure.

Checking the usual off shore supply centres and looked at the cost + shipping of a new & rebuilt pumps.$Ouch!

I see that there is a repair kit that includes all the seals for the pump, but the kit does not include a new impeller. 

Questions to the brain trust;

Has anyone rebuilt their pump? is there a replacement impeller available? This may require machining the bore.

I have not pulled the pump apart, yet, but probably will, just to have a look.

Is there anywhere in Australia that I should check for a new or rebuilt replacement?

Is there a compatable audi pump that works. 

Is there anything that I missed in my trouble shooting that would imply some other conclusion? 

Anyone with a used pump that they are not using and want to sell.

[81SC]

Hey Brian,

I believe the power steering pump on the 944's are a vane type pump. I would apply some basic hydraulic system principles to try and diagnose your problem, I have a little bit of experience working with heavy industry hydraulics ?. Check list.

- Correct type of fluid & level. 

- Pump turning & in the correct direction.

- Test for pressure & flow.

- Blocked inlet to pump, eg: strainer or blocked inlet from foreign matter or collapsed hose. Normally the pump will be noisy due to a lack of fluid.

- Blocked outlet, again pump will be noisy or pressure relief valve will be noisy.

- Internal pump problem, eg: sticking vanes, blown internal seal allowing fluid to just recirculate, sticking relief valve not allowing pump to generate pressure.

You are correct about pulling the pump apart to have a look, after you have discounted all the external problem possibilities. Remember to mark the pump components before disassembly to help with the correct orientation when reassembling or take photos. If you can, post some photos when you have the pump apart. HTH.

[TINGY]

There is a guy in SA who sells heaps of parts on gumtree, look him up @brian in buddina he may have a pump to sell.

[Jason E]

4 hours ago, TINGY944 said:

There is a guy in SA who sells heaps of parts on gumtree, look him up @brian in buddina he may have a pump to sell.

I have his details if you need them Brian.

[brian in buddina]

On 24 August 2018 at 10:32 AM, 81SC said:

Hey Brian,

I believe the power steering pump on the 944's are a vane type pump. I would apply some basic hydraulic system principles to try and diagnose your problem, I have a little bit of experience working with heavy industry hydraulics ?. Check list.

- Correct type of fluid & level. 

- Pump turning & in the correct direction.

- Test for pressure & flow.

- Blocked inlet to pump, eg: strainer or blocked inlet from foreign matter or collapsed hose. Normally the pump will be noisy due to a lack of fluid.

- Blocked outlet, again pump will be noisy or pressure relief valve will be noisy.

- Internal pump problem, eg: sticking vanes, blown internal seal allowing fluid to just recirculate, sticking relief valve not allowing pump to generate pressure.

You are correct about pulling the pump apart to have a look, after you have discounted all the external problem possibilities. Remember to mark the pump components before disassembly to help with the correct orientation when reassembling or take photos. If you can, post some photos when you have the pump apart. HTH.

@81SC Brett

Thanks for your detailed response. This is where I am at:

I believe I am using the correct fluid, Dexron , but it also says "with STOP LEAK" will this be an issue?

the pump/belt has not been removed since it stop working. So I am assuming its going in the correct direction.

I tested for pressure where the electrical indicator connection on the pump housing screws in,  with no pressure registering on the tester. Not sure if I did this correctly as I got a zero reading. Is there any other locations to check the pressure?

I took the PS fluid reservoir off and the attached rubber hoses. I did not blow air through the rubber hoses, but should probably dissemble & do it again to blow air through the line. I read the reservoir has a built in strainer/filter, which is not sevicable without buying a new reservoir. Therefore  I rinsed the reservoir in petrol to see if any foreign matter were clogging it up. No foreign matter observed. No noise from the pump when running & turning the steering wheel. 

Where is the pressure relief valve? 

The PS pump has no noticable leaks. 

I have not removed and dissembled the pump yet.

I have been driving the car with no PS, which is ok unless parking. Today I was under the car and noticed in the PS lines what I think is a leak at a rigid hose to rubber hose fitting as per the 2 attached photos. 

https://imgur.com/gallery/cbqmIY0

What you are looking at is the alloy cross member under the oil pan, as viewed from the front of the car, and the hose from, or to, the PS rack. I have cleaned & wiped away the leak residue. I will do another test drive later today to see if we have a drip at the same point. I originally thought it was the oil pan gasket leaking as per my original PPI last year.

Questions:

If it is leaking at this hose fitting location can I take the hose off and have another one made by a hose fitting place? It looks like some kind of compression fitting. Or am I better off to visit a power steering specialist? Would this leak be enough to have no power steering at all? 

I checked the Adelaide chap's gumtree ads. I have talked to him before. He has a used PS pump listed at about $400. The age/milage is not listed. UK & US replacement pumps would be about the same cost. Reading on Rennlist its the condition of the shaft which is important. It doesn't make sense to buy an old one, at that price, when I could get a new/rebuilt one.

The gasket kit for this pump is about $25 US and looks pretty straight forward to install, according to youtube. 

Has anyone found an Audi or VW compatable PS pump?

Its a "ZF" pump. the rivited on plate has lots of numbers:

110 bar

1507359 not sure if this is a part number or serial number

7681 955139

"W" checked by Walter???

11.87 looks like the date

the part number listed in the Porsche Katalog is: item 17, vane type pump (944S) #944 347 432 04 

Anything else I missed?

B i B