I need some help diagnosing a clutch pedal issue even though the car shifts fine. 2000 WS6 M6. With the car at idle, after about a second of barely/lightly touching your foot to the clutch pedal, it will begin to slowly/gradually go to the floor. After it does this you can let off the clutch and it will return back to a full pedal so you can shift. It does this slow descent with a little foot pressure every time it’s tried.

I haven’t had anyone to help this weekend so I haven’t bled the clutch using the traditional method but I did try bleeding from the master cylinder reservoir with a mityvac. No bubbles came from the fluid with the mityvac.

Before I had the car I know the clutch was replaced, so I’m sure the slave would have been replaced but I do not know if the master cylinder was changed.

My suspicion is the master cylinder but transmissions aren’t my strong suit so I’d like everyone’s thoughts about this pedal situation before I start throwing parts at it.

Thanks!

 

why not vac it at the slave? How much pressure are you putting on the clutch pedal when it drops to the floor? When you let off does it push all the way down over and over with the same pressure? When it is down can you put into gear or change gears?

If you are just putting a light amount of pressure and it drops to the floor and you can't go into gear or change gears without grinding then your probably looking at a hydo issue. If you get to the floor and it changes gears fine then you probably have a clutch pressure plate issue. If it looks like the pressure plate you should find it slips easy, so try a run on to the highway in 4 from like 30 with it floored to put a huge load on the clutch to see if it slips. If it takes even that much load.

 

When I put my toe on the pedal I'm not putting on much pressure at all. It's a slow descent to the floor, roughly 5-7 seconds. Then when I let off the pedal it will rise right back up and you can shift like normal. When shifting it will engage well before the floor. It only really goes to the floor after putting slight foot pressure. I can still shift even if I don't allow the pedal to fully rise back to normal position, it just engages the clutch and takes off with less pedal travel than usual. You run through the gears and essentially shift normally (or at least I haven't noticed any problems), but sitting at idle/traffic it's doing as I described above. The car drives normally in every other respect.

 

sounds like the master is going bad based on it working at different levels depending on it leaking down first or not.

 

Thanks again for your thoughts so far. I've tried bleeding with the Mightyvac again including pumping the clutch pedal while under vacuum. No bubbles. The clutch fluid has never been low so I don't think there is a leak anywhere. Again, transmissions are not my forte so I may be asking dumb questions, but does anyone have any other ideas on what's causing this other than the master?