Clutch? Slave Cylinder?

[Bartenderfloyd]

Here's a good one. I have a 2004 A6 2.7T 6-speed with 134,500 miles on it. I know my car really well and am very in tune with every rattle, vibration, or whatever as I'm sure you all are with your own cars. Four days ago while driving into work (30 miles, mostly highway) I was approaching a toll and had to down shift. When I pressed the clutch to the floor it felt like the pedal was rumbling or pushing back. Almost like it was poking back at my foot. Also, it didn't shift out of gear and back into gear as smoothly as it normally does. I put it back into 6th and continued in to work. As I came off the exit and onto the side roads the same thing was happening and the shifting became more difficult, almost as if the clutch was not disengaging. I got to my parking lot and let the car sit for a few hours. We have a small garage at my office so I tried to pull the car into the garage during lunch but it just would not go into gear. I shut the car off, put it in reverse after a few seconds of playing with the stick, and started the car in gear. I did feel the car tug as I started it, confirming the clutch was probably still engaged a bit. I put the car up on the lift to look for leaks thinking that the slave cylinder was shot but I didn't see anything. No leaks whatsoever. Then, thinking that I may have low brake fluid, I topped the fluid off. It wasn't low but I put in an ounce or 2 anyway. That didn't make any difference. I now try to back out of the garage and it absolutely does not want to go in reverse with the engine running or off. I push it out of the garage and with the engine off, play with the stick enough to get it to shift into first. I figured once I got rolling I'd be able to shift. The car wanted none of that. As I was rolling in first gear I tried to shift to second and it would not pull out of gear. I even gave it a good tug but kept it short of using all my strength to pull the gear shift out of first, I didn't want to further complicate the issue by grinding a gear. At this time I assume the clutch is bad and take the train home. Yesterday I get back to work and the car shifts fine. Just as smoothly as ever. I drove it home and not once did it give any indication that anything was wrong. Shifted smooth, no vibrations, basically making a mockery of me. Any ideas on what it could be? Throw out bearing maybe? Maybe one of the clutch springs broke, got lodged in something and then dislodged itself? Could that ounce of brake fluid really have done something?

[johnkk]

I've yet to have a clutch problem with my 01 6spd, so my comments are from prior clutch mishaps. If no leakage, normally the slave is OK, and the problem is the master cyl.

Sometimes a speck of "stuff" can get between the seal and the bore and you lose pressure. The debris might migrate and the clutch works OK until it gets caught again. Pumping could dislodge the debris.

If the slave seal is blown, you will normally get leakage, but I'm not sure if there is an opening for the fluid to get out and drip on the ground. But watch the level very closely and maybe kluge a dipstick to measure the fluid depth. If no drop in fluid or drip, I'd bet on the master.

I've had two pressure plates go(Borgward and Triumph), but when those happened, failure was sudden and complete.

I've never done an Audi master, but probably lots of stuff to get out of the way. I don't have access to my manual now, so I'm not sure if they discuss this or if so, how bad the job is.

good luck.