Rusty Spokes

For those with ZF power steering pumps..particularly the 12v V6 pumps that always like to leak..they are notorious for being a problem. The same basic pump is used on Porsche 924/944 and other cars as well. You can use a Rennbay 944 kit on our Audi(s)...RB002 Power Steering Pump Seal Kit @ $21.50
http://www.rennbay.com/

The pump shown is a very wet Audi A6 120BAR power steering pump. The pump leaks and also sucks air..making for groans and noises.

The Audi 90 and Cabriolet use a 100BAR pump. It has a green tag. You can rebuild your Audi 90 pump with an A6 pump. The pressure relief (100BAR or 120BAR) are in the back housing along with a flow valve. That is what determines the part number. The back housing will not usually wear out..the front section has the pump body and seals and is the same on all the ZF pumps Audi used on the 12v V6 engines..as far as I can tell. The pump front body is very tough too..but if you have a problem there..any PS pump off a 12v V6 will swap out..just use the back housing that came with your car and has the correct part number.

Take the PS pump cassette off your car..you will need a stubby 6mm allen (1/4 inch drive works) on a "wobble extension" to get to the back two 6mm allens on the cassette.

Remove the fittings on the pump and be prepared for a fluid dump when removing the hose clamp on the intake side of the pump.

Once removed..plug the intake port and top output port with paper and plugs as best you can. You want to avoid all the dirt and grime getting inside the pump when you clean it. Old CHF11s PS fluid turns to wax and is very hard to remove...use some diesel fuel and a good brush in an old pan. If that will not work..use gasoline..with great care. Brake clean and carb cleaner just don't work that well..but you can try.

Once clean..mark the front and back pump parts for alignment when reassembling then remove the four 13mm bolts and separate the front and back side of the pump.

Once apart..you will see the big "O" ring and the internal seals on a plate

The big leaks are the front nose seal, big "O" ring..internal seal(s) and the threaded plug on the bottom of the pump.

Gently remove that front seal plate..it pops off and lay it aside. You can replace the seals on it later.

Once that seal plate is off the vanes in the pump can fall out..and makes it very difficult to reassemble..they fit one way only. To avoid the problem..smear the pump and vanes with Vaseline to hold the vanes in place..then get some Saran wrap and place it over the pump..that will hold the vanes in place. cut out the center of the plastic and struggle to remove that "C" clip on the pump shaft..it is very fiddly..the "C" clip is actually a soft steel rather than a spring steel. You can spread it and walk it off the shaft..then when installing it later walk it back on the shaft then close the "C" clip up with some pliers.. just be careful and do not loose that clip..if it goes flying you will have a tough time finding another. It is not in the kit.

Once the "C" clip is off..pull the pump shaft..now you can replace the front seal. Chance are that seal has been is service for twenty years and will be tough to remove. Note the old seal is "flush" with the pump body...then using a socket..drive the old seal in slightly..that gets the seal loose...now you can pop it off the pump body. Install the new blue seal with care..I use Vaseline on the new seal and set it in place and using a socket with some light taps..install it till it is flush with the pump body...like the old seal.
Put some Vaseline on the seal lips too then reinstall the pump shaft..turning it so as to engage the pump vanes..then reinstall that "C" clip..with great care and once in the groove on the shaft..close it up with some pliers. Be sure it is fixed in place and not coming loose.

Now clean up the Vaseline and get that pump plate..remove that rubber seal and plastic holder.. note their shape and position (don't be surprised if they fall apart and are worn out) and put the seal holder back on the pump body..it fits on two posts..then then get your new plastic holder and rubber seal and put them together in your hand. Once together install them into the groove in the pump plate..walk them in with care..you may have to push the plastic seal holder in the corners as you install.work it in. Once seated in place..wipe it all with a coat of Vaseline.

Now get some acetone and some Q tips and a clean cloth. You want to clean that groove on the pump where the "O" ring fits..clean all the oils and wipe that "O" ring area down..don't slop acetone around on the inside of the pump or any of the seals..just clean that groove area. And then clean the smooth surface on the pump backside section where the "O" ring will fit with some acetone..get the oil off that part too.

Now if you forgot to mark the pump bodies..so they will reassemble in the same position (if you miss-match..there will be a port for oiling the pump shaft that is blocked and you will destroy your pump)..no worries..look for the oiling port..see it on the 14th picture? Look on your pump front and rear bodies and you will see a small port..line those up so they are mated when you put the pump together.

I used a slight smear of Loctite 574 on the big "O" ring..there are two "O" rings in the kit..just match up the one you need.

With a very light coat of 574 on the "O" ring..seat it into the groove on the pump and reinstall the back pump cover..line up your marks and be sure that oiling port front pump and back cover are mated.

chis-cross tighten the four 13mm bolts on the pump till snug..then tighten to about 15/18 ft.lbs..check it twice.

Last step..get some JB Weld. Clean the area around the threaded plug on the bottom of the pump with acetone..get it clean! Make up a glob of JB Weld and smear it on that threaded plug area.

That access plug looks like it was made for some internal pump machining when the pump was manufactured then threaded with a plug..with some adhesive that long ago lost its ability to keep dry..so just cover the area with JB Weld.

Let it all dry overnight and put you newly rebuilt pump back in the cassette. Install it on the car.

Some will want to use Pentosin CHF11s PS fluid..and that is fine. I use Maxlife synthetic ATF. Porsche used the same power steering pump internals and they recommended AFT in the 944//924. So I go with ATF as the PS fluid of choice

gag4o

Great write up. The topic needs to go to the Golden Reserve
Soon I will do it too.