If you have a 5000 or pre-92 100/200 you know what a pain it is. The seal kit at $60 is a joke, two months later and it is leaking again. Pentosin is not cheap either and sticky like molasses. The ZF rebuild, pricey, and is not guaranteed against leaks either.

I contacted Pentosin to find out what material is good to use as a replacement:
“… we would like to recommend the use of NBR elastomeres, but if you want you can use H-NBR or FPM materials.”
If you buy NBR O-rings from McMaster it will be lot cheaper, probably less than $10 per 100 but who wants to replace them every two months.

The fix is to use copper or aluminum crush washers similar to the ones used on FI and brake systems. The problem is finding the size 22mm X 18mm X 2mm. I made mine out of copper and aluminum .063” thick sheets and after 12+ months NO LEAKS. The hydraulic pump has two chambers with 8 pistons, two pistons are HIGH PRESSURE for the brake system and charge up the brake “bomb” these are a must. The other six are for power steering and are optional since the pressure is a lot lower.

 

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I am not sure if ATF was designed to work at the pressures that Audi pump put out. Most automatic transmissions rarely see anything over 600psi the hydraulic pump on 100/200 models can generate 2200 - 3000psi. But if it works without a problem, who am I to argue. As far tightening down the screw, been there done that, either the 5000 pumps puts out less pressure, the pump is worn or it is the physical properties of the ATF itself. I know that for me it didn't work, even after tightening it with the proper drag link it still leaked and not to mention I damaged a few screw caps. A trip to the local junkyard indicated that this is a popular fix as was indicated by all those striped caps and the pumps still had evidence of leakage.

 

On May 1987 I´d bougth a new Audi 100 KU 2223cc.,5 cyl (the 5000 US).
At the first trip (second day run) by very mountain curverd roads, the power steering presure line damper hose (the going to down line) begins to leak..
Warranty service replacement needs soon a second cure. OK from.
Late, the pump itself (maybe at two years) begin to leaks too. O rings replacement dont cure it at all. Less leaks, but leaks, sothat I must to add G2000 green gold frequently. A very cumbersome matter in a new car.
Late, the steeering rack goes in rubber prot. damage and leaks too.
Only the whole replacement fron the pump (from a yunk yard) and steering rack Audi serv.rebuilt could cure these leaks.
I deeply suspect for a non normal presure ratio in the system form the factory.
Nowadays, with 17 years and 267.000 Kms over. NO LEAKS.
Of course, because the car remains very reliable, I will use it as far as possible, beacuse it has been a hard battle, and I like this my second Audi car which engine keeps wonderfull.
I got shared my bad experince with several other european Audi 100 owners, and frequently have a similar experience.
I hope this a Audi cars lack, frequently reported. And not too easy to fix.
Helped..?
M. Urosa
Madrid.

 

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Superdave,

Not all ATF is synthetic unless you specifically buy labeled as such. I don’t think that the hydraulic fluid in an Audi gets as hot as Transmission fluid, but for the hell of it I will take some measurements. ATF also contains special additives to work with the friction plates (clutches) in a transmission, these additives have compatibility issues with certain types of o-rings, rubber seals and plastic parts. If you get ATF on radiator hoses they will swell and rupture. Many manufacturers don’t even recommend ATF for power steering and suggest using special PS fluid instead. ATF and Pentosin have different viscosity as a result you might not be operating at the same pressures as Pentosin. A pressure gauge will only be able to confirm if it makes a difference. The fluid also acts as a lubricant, too thin and the bushings wear out prematurely, too thick and you blow seals, hoses or even crack the pump. As an example you don't want to us differential oil in your motor as well as motor oil in your differential.

How did you come to the conclusion of using ATF? I am not questioning your solution or saying that it is better or worse. If it still works without problems I am not going to argue because you have the living proof! I did an extensive search to see if there were any upgrades kits or solutions to what seems to be a very common problem. The only info I found was to use copper or aluminum "crush washers."

 

I don't think using ATF is very safe. Remember that the steering pump also supports the brakes.

 

The safe replacement for the power steering oil is plain mineral oil that you buy at Walgreens etc for about $6.00/ quart. I've used it for a year while tracking and fixing leaks. Now back to using the $$$ stuff Pentosin as it probably has a preservative additive.
scotty@bestnetpc.com

 

I have a 1993 V8 Quattro and the p/s pump is leaking. Looking at the responses about p/s (hydraulic) leaks I have a couple of questions.
Am I correct in thinking that the power steering pump for the V8 is similar to pumps referred to in this thread?
When talking about crush washers are we talking about pulling the threaded plugs that have a cross on them around the circumference of the pump and replacing the existing rubber(?) seals with crush washers of the same size and thickness?
Do these have torque settings that are critical?
Has anybody had any more experience with using synthetic ATF as a fluid instead of the $20/liter that I have been using? Did you just start adding it or did you flush the system?
Is mineral oil from WalMart similar enough ( with the exception of preservatives) that I can safely use it until I get the leaks fixed?
Thanks. Steve.

 

I have a 1993 V8 Quattro and the p/s pump is leaking. Looking at the responses about p/s (hydraulic) leaks I have a couple of questions. Am I correct in thinking that the power steering pump for the V8 is similar to pumps referred to in this thread?
I checked on Rock Auto web site and see that that ’91 100Q and’93 V8 both use the same hydraulic pump rebuild kit. So they are probably the same. The hose mounting might be rotated differently?

When talking about crush washers are we talking about pulling the threaded plugs that have a cross on them around the circumference of the pump and replacing the existing rubber(?) seals with crush washers of the same size and thickness?
You don’t have to do all of them, there are a total 8 pistons and "+" caps, six are for the power steering and generate less pressure. These six caps are located around the same axis. The other two have smaller pistons but generate much higher pressure and are the ones that leak most often. I replaced only these two with crush washers.

Do these have torque settings that are critical?
There are no official torque figures for tightening the DIY crush washers. Once you feel that the "+" cap is seated give it about 1/16 turn. The thread pitch is large so it doesn’t take much to crush the aluminum or copper. I would rather have the cap under torqued and being able to tighten it some more then over tightening and destroying the washer.

Has anybody had any more experience with using synthetic ATF as a fluid instead of the $20/liter that I have been using? Did you just start adding it or did you flush the system? Is mineral oil from WalMart similar enough ( with the exception of preservatives) that I can safely use it until I get the leaks fixed?
Given how expensive pump components are I would not take a chance with either ATF or mineral oil, Pentosin probably contains all sorts of additives for lower corrosion, lubrication, longevity, antifoaming agents, reduced flash point, etc.