I'm the most recent lucky winner of the classic pentosin puddle on my garage floor from my '03 Turbo. Transmission casing right about the driveshafts is wet so I'm pretty sure it is the clutch slave cylinder right above it.

I've looked it over and did enough research that I know I need to swap out the slave and accumulator.

Question is, when the slaves give out, where are they failing and leaking from? Is it an o-ring seal or whatnot that gives out? Not looking to rebuild it, just wondering.

I know the second common failure mode is for it to leak internally and pass excess fluid to the front reservoir. Is this also a matter of a bad o-ring seal?

 

I can't answer your question so my post is more of a bump . From what I have read its a seal that fails on the slave if it leaks on the floor and the fluid going back to the reservoir (I had this problem) is fluid bypassing the seals internally and being forced back.

Hopefully somebody with more knowledge can chime in.

 

yes, it can/will also "seep" inside the cabin ( rare ) from under steering column. in addition to the back pressure puking from the ps res to the front under the bonnet.

ya can't rebuild it. you can/should replace with new lol

 

Which is too bad as it's likely just some bad seals in the end. People have been rebuilding master and slaves forever in other vehicles, and parts are readily available for that. But then again, our cars are so few and far between that it's not likely a 3rd party manufacturer is going to step up and produce anything in such limited volumes.

It probably is just a few key seals within the slave that's failed. Given how often these things puke, it would be a nice option.

Anyone have old failed slaves sitting around? I will replace mine with a new one, though I'm going to pull my failed one this weekend and tear it down to see where it's failed out of curiosity.

 

I had an Audi GT coupe years ago that the slave was bad on and ridiculously priced after days of looking sourced seals and rebuilt. I guess you could source seal and rebuild but I would just buy a new one.

 

i shouldve said I couldn't repair one lol. you? maybe good luck w it!

 

Like I said, I will replace with new.

But I'm still interested in how these are failing for the small potential that we can solve/improve on what's there. If not, at least we can evolve the hive mind with better understanding of this component.

 

Its almost always a worn/torn seal I usually honed out rough spots and put new seals in and they were good to go= never had one I couldn't repair.

 

well, since you're on that one pls try and explain the failing accumulators! they are 3:1 failure rate!

 

The fluid is hard on the bladder in my opinion.

 

Swapped out the slave tonight and confirmed it was leaking at the pushrod slave cylinder. My accumulator was not holding boost for a couple months now. Not sure if that's what exasperated the slave to fail as well. The slave and accumulator failures seem to go hand in hand from looking around on the boards.

Whats interesting is seem what pentosin does to rubber. The slave boot over the pushrod is so swollen that it won't stay in place by a long mile. Like a hot dog in a hallway....lol. Made sure I cleaned up all the pentosin that dripped about during the swap.

Now to finish my clutch swap and I'll tear down the slave when I get a chance.

 

Yes in fact the rubber inside the accumulator seems to suffer from Pentosin. Did open one and found the rubber with multiple cracks. Also did a slave surgery and did not found anything obvious for the reason I had fluid migration.(front clutch reservoir overflowing) You can see the piston that operate the clutch on top of the picture has two sets of o-ring. I guess the smaller one is for the pressure coming from the steering pump and the bigger one is from the clutch pedal. The migration should happen in this area but both seals looks fine and the cylinder looks also fine….There is also some check valves and release valves that can be at fault but the function of these are still a mystery for me

 

^ I'm going with jpflips "failure is where the pentosin meets the rubber". Given their seeming dislike for one another the accumulator seems an odd choice for so critical a function. Of course it can be eliminated but that's something I've chosen to keep stock.

I just replaced slave and accumulator both and the accumulator is acting up already with intermittent hard pedal.

As long as clutch action stays within normal limits, I live with it. Though I must say I tend to double clutch much less than I might ordinarily! since I know this is my cars Achilles heel lol.

Stupid design.