# Slave cylinder, or master cylinder problem?



## golfcabriolet90 (Nov 21, 2004)

I'm having some trouble with my clutch.
It seems that after I have driven for a while and the engine bay gets up to temperature, my clutch pedal gets very soft and the point at which the clutch grabs also drops lower. The pedal does not get stuck to the floor, it travels all the way back up again every time.
I can still drive the car and it doesn't slip or anything but it gets more difficult when you have so little travel to engage the power transfer.
I tried flushing the system with new vw brake fluid as per the bentley manual, the clutch as well as brake system were done.
To start with it felt great, but then later it got soft and did the same thing.
If I leave the car for a while to let it cool, the clutch goes back to normal function until its warm again
What do you think it could be?
Changing the slave cylinder is a big deal, right?
Could it be the master cylinder? Or the bleeder valve?
Thanks for any help you can give me.


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## apstguy (Apr 3, 2006)

Sounds like the clutch master cylinder. It is also the cheapest to replace, so start there.


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## golfcabriolet90 (Nov 21, 2004)

*Re: (apstguy)*


_Quote, originally posted by *apstguy* »_Sounds like the clutch master cylinder. It is also the cheapest to replace, so start there.

Thank you, you have no idea how glad you've made me.
I'll try replacing it then.
What are the classical symptoms of a slave cylinder failure though?


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## Veedub_junky (Aug 13, 2005)

*FV-QR*

Typically a slave cylinder issue presents with the pedal dropping to the floor and staying there. I had some funny stuff with my clutch (not the same symptoms as yours though), and it turned out to be the master. And yes, slave cylinders are a huge problem on these transmissions because it's internal - you have to drop the transmission to get at it. Hopefully you are able to dodge that bullet. Good luck.


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## apstguy (Apr 3, 2006)

Slave Cylinder failure almost always drops the clutch pedal to the floor or some variation of. I think it has something to do with the spring inside it but I didn't keep my old one to take apart and see







When seals in the master brake or clutch cylinder go bad, they let some of the pressure back to the other side of the system reducing the amount of travel a pedal does.


_Modified by apstguy at 5:03 PM 3-31-2009_


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## jefswat (Jun 10, 2008)

*Re: (apstguy)*


_Quote, originally posted by *apstguy* »_Sounds like the clutch master cylinder. It is also the cheapest to replace, so start there.

I never looked up prices but I would think the bleeder valve is the cheapest and easiest to do. Problably not the problem though


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## V_aaRg_6 (Nov 19, 2008)

*Re: (jefswat)*

I am having a similar probably in my vr6, except my clutch pedal goes "soft" after a downshift, especially noticeable on a 3-2. I am going to replace the master cylinder in a couple of weeks, Ill let you know how and goes and I will be keeping an eye on this thread. Goodluck http://****************.com/smile/emthup.gif


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## golfcabriolet90 (Nov 21, 2004)

*Re: (V_aaRg_6)*

Well I thought I would update this thread as I've made some good progress.
After doing some search in the R32 forum I came across this thread that also confirmed my own doubts about the actual bleed process of our clutches.
http://forums.vwvortex.com/zer...age=1
Th problem with bleeding the 02M clutch is basically that the slave cylinder is never actually fully bled or even flushed with new fresh fluid.
All the tubing to left of the bleeder valve is never replaced.
So I went at it and thought that something had to be done about that, took the bleeder housing of and inserted a small tube into the slave cylinder piping. 
With a syringe filled with fresh brake fluid and no air bubbles in the syringe or tube, I was then able to push it down somewhat and displace the old fluid with the new.
After doing this very carefully, I bled the system as per the Bentley manual.
Result: The clutch has never gone soft since this, ever, it is completely constant regardless of how hot it is or how hard I've driven the car.
And I never replaced the master cylinder either, I wanted to give this a shot first.
So if your problems were similar to mine, give this method a try.
If need be, I can do a more thorough description of what I did, it's pretty simple.


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## Veedub_junky (Aug 13, 2005)

*Re: (golfcabriolet90)*

Please do write it up - maybe in a new thread so it can be added to the DIY thread. I'm having a little trouble visualizing your process, so a pic or simple diagram would be really helpful if you can do that. 
Anything that helps possibly resolve a clutch problem that doesn't involve dropping the transmission is worth a shot and definitely welcome!


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## V_aaRg_6 (Nov 19, 2008)

*Re: (Veedub_junky)*

I second that http://****************.com/smile/emthup.gif


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## PhReE (Sep 16, 2004)

*Re: (V_aaRg_6)*

Oooh, this is good information. Yeah, please post a more detailed write up somewhere http://****************.com/smile/emthup.gif


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## golfcabriolet90 (Nov 21, 2004)

*Re: (Veedub_junky)*

Ok sure, I'll post a new thread with step by step illustrations and descriptions.
Will have some time to do it next week.
Still no probs with the clutch thus far


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## golfcabriolet90 (Nov 21, 2004)

*Re: (golfcabriolet90)*

If you haven't already seen it, then here is a link to the guide for doing this flush, hope it helps.
http://forums.vwvortex.com/zerothread?id=4376420
Thanks
All is still 100% in order with my clutch, no softness despite being in traffic jams in the city with a/c on etc. Works like a charm now.


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## AZN dubs (Sep 18, 2007)

bringing this back from the dead. i have the same problem as the OP except it happens when the engine is cold. the revs hang when i change gears in the morning, and i don't think that even when i have the clutch all the way on the ground, that is open.

changed my trans fluid already..
was going to change the master before the slave.. i have had a slave cylinder problem in the past and it happened over night.. this has been going on for a month or 2 now so im pretty sure i can rule our the slave cylinder.


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## ClutchMan (Oct 17, 2020)

Bumping this thread.

Appears I have pretty equivalent problems to thread starter.

Clutch has in general been very soft. Problems started with clutch dropping lower to the point where it even got stuck at the floor. Problem is especially bad once the car has warmed up.

Have tried bleeding, both by pushing oil through slave cylinder and by applying 2 bars of pressure at reservoir (bleeding at slave valve).
Have tried "bleeding" clutch release bearing/slave cylinder by inserting small tube, as descirbed in this thread.

Nothing seems to have improved the situation. Upon checking with workshop, I was told it was likely the master cylinder and that it's a known point of failure on these vehicles (had recently fixed another one with similar problem).
My master cylinder appears to be somewhat dry on the outside upon inspection (without complete disassembly).

Could it still be the master cylinder, even though it's dry? Or is it almost 100 % certain it's the slave cylinder / clutch release bearing?

Appreciate any input.


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