Clutch Problems

[RJohnson]

My car developed a clutch problem yesterday, was fine on a 10 mile outward journey, but it felt wrong as soon as I started it for the return journey, the  pedal feels different, clutch is slipping even on part throttle/low revs, and also dragging when clutch is down, I cant get it into reverse with the engine running. I had the car remapped December 2014 - Revo stage 1, after that it has had some clutch slip at 4000 rpm, full throttle in 4th gear upwards, I have driven round this, always lifted of when slip started, and used higher revs when going for it.  So, I don't think the clutch has worn out - surely that would have got progressively worse, and why would a worn clutch be dragging ? I wonder if it could be a master/slave cylinder problem, or even some part blockage in the fluid pipes ?
Any thoughts welcome !
Also can someone tell me what the round black plastic thing is half way along the clutch fluid line, its approx. 60mm diameter, with fluid lines going in/out on a tangent - it is in the left n/s corner of the engine bay ?

[RJohnson]

Come on, someone must have some thoughts !
By way of update, tried re bleeding the hydraulics, also put a clear plastic pipe on the bleed nipple, opened it and got a friend to push the pedal, fluid rose up the pipe 6" or so - that, I think shows the master cylinder is doing its job.
So, took the box out, clutch off, and it looks ok, although I did notice that the pressure plate friction surface is slightly concave - put a ruler across- it touches at the outer circumference, but there is a gap off approx 1mm to the inner circumference, and the driver plate is clearly more worn on the outer on that side, suggesting that plate has been concave for some time and probably shouldn't be.  Driven plate is 7.5 mm thick at the outer, 8mm inner. Pointless putting anything suspect back in so its having a new pressure plate and driven plate.
I tested the slave cylinder by attaching a clear tube and pushing it in- fluid goes up the tube as expected, smooth action and no leaks.
The DMF has about 20mm play when rotated - dosnt seem excessive- I have seen reference to 20 degrees being acceptable, and it also rocks, ie when I push one side in towards the engine and then the other it rocks by about 5mm total, I don't know if that's acceptable or not ?
 Tempted to replace the lot, DMF clutch and slave, but never like replacing things just to see if it cures a problem. I would have been happy to see one or more clearly knackered bits !!
I did check the gearbox - rotating the input by hand, selecting gears etc - all seems fine

[r5gtt]

If you haven't done so already, check your release bearing but judging by what you've said sounds like the pressure plate. I could be wrong but all else checked Id say pressure plate and clutch plate.

word of warning!! regardless of concentric slave cylinder condition unless new, replace all clutch items as recommended as you don't want to be doing the job twicentre trying to save a few pennies on the CSC.

Pictures of the clutch drive plate would have been ideal in these situations as you did say you removed to check.

[amanda]

Did all wheels appear to lock up?...losing speed and maybe white smoke?

[r5gtt]

I for got to mention the tolerance on the dmf irrc is 15mm of play. I posted so thing about this a while back but won't be able to find the thread.

[RJohnson]

Many thanks r5gtt, I thought the VW clutch repair manual might give the DMF tolerance, but it dosnt !
 I think I will replace the lot - dmf both plates and slave.  I was doing some interweb reading on bleeding, loads of threads about people struggling to bleed them properly, what fun !!

[r5gtt]

We are talking vw   

I've found that using a pressure bleeder does the job quickly. Just keep topping up the fluid

Let us know how it goes once you've taken it all out and replaced.
Good luck

[RJohnson]

Update, got a full Sachs clutch kit today - DMF, clutch plates and slave cylinder. I filled the slave with fluid prior to fitting, got it all fitted tonight, used a hand held pump to pump fluid into the bleed nipple, bled fine in about 2 minutes. It has cured the problem, and no clutch slip - but it looks like the old clutch was only working over half of its surface due to the concave pressure plate.
So, happy its fixed, could have done without the cost/graft !

[r5gtt]

Glad you've sorted it out

[snowley]

Well done for sorting and doing the work yourself - not an easy job at all!