Help needed to resolve a leaking clutch slave to metal pipe joint.

[Ed Chappell]

It is a long story but I bought my RS4 just after the clutch had been replaced, I think by a local non Audi specialist garage. Whoever did the clutch did not do a good job.
The slave is a plastic one and is supposedly new. The joint between the slave and the metal pipe going into it was leaking quite badly.
I stripped the underside of the car to get access to the joint and disassembled it. The clip was retaining the metal pipe firmly but the pipe moved quite a lot with the clip still in position, hence the leak.
When I got the joint apart there was just a rubber nipple fitted to the end of the metal pipe. There are no seals shown in any of the ELSAWIN service pictures and EKTA does not show any either.
After some research I found a VAG joint repair kit 1K0 798 741 which contains a rubber nipple and a small O ring.

My question is where does the rubber O ring go?
Does it go into the hole in the clutch slave first followed by the metal pipe and nipple?
Or onto the plastic retainer fixed to the pipe first then fit the nipple?
I have experimented with both and I can't get the spring clip to engage and hold the pipe firmly so the joint still leaks.

I am sure someone will have faced the same problem so any advice is welcome!

[Ed Chappell]

I have resolved the pipe connection problem now.
But now I am having a real issue replacing the slave cylinder while the gearbox is still on the car.
I have followed the Elsawin guide for replacing the slave cylinder but cannot get the slave to fit into position.
Anyone had similar problems or hints that work?
Thanks

[Ed Chappell]

Just to close this one off.
There is quite a lot of info out there on the 3 types of coupling the various VW/Audi models use. Mine just used the rubber nipple in the kit. The rubber used in the kit from Audi is quite hard and it can be difficult to push the fitting home. Aftermarket equivalents are usually a bit softer.
My plastic fitting had gone brittle so I had to replace it. Not all aftermarket plastic fittings are good moldings so you may have to buy more than one from different suppliers, so plan ahead.
I solved the problems fitting the slave cylinder by using 10mm wide dressmakers ribbon to compress the slave cylinder by about 80% by before fitting. It is very thin and does not affect the fit in the gearbox hole.
Cutting and removing the ribbon is very fiddly but once cut you could leave it in situ if you want.
My clutch is working now with no leaks..........finally.

[Ed Chappell]

An update to this saga.
Thinking my clutch problem was solved I reassembled the car.
After running the engine for 20 minutes and dipping the clutch several times it suddenly went to the floor.
I discovered the metal pipe had popped out of the plastic fitting in the slave cylinder under pressure which was different to the previous failure mode I had.
On investigation I discovered that the heat from the exhaust downpipe had heated and softened the plastic fitting so that the retaining ring on the metal pipe pushed past the groove in the plastic fitting.
The plastic fitting I used was an aftermarket one since original VW/Audi ones are not available.
The solution was to visit the local breakers yard and obtain some genuine plastic fittings from scrapped VW cars. These usually are fitted well away from the exhaust system on most cars so the fitting does not get hot and soften or go brittle.
After replacement and repeated testing with the engine hot everything worked reliably.
Genuine VW/Audi plastic fittings are marked DE 36 and are made from quite hard plastic and the quality of the molding is much better than the aftermarket ones too.

This solution has fixed my problem (I hope!)
So the bottom line is if you have to replace the plastic fitting that holds the metal pipe into the clutch slave use a genuine VW/Audi one on your RS4 or you could have problems.