Hydraulic Clutch Audi A3 8PA 2.0 TDI Not Disengaging

Hello,

I'm experiencing an issue where the clutch occasionally doesn't disengage, and in those cases, the pedal doesn't return.

Brake fluid level is OK, and there are no visible leaks.
Everything is dry on the clutch master cylinder located in the passenger compartment and engine compartment, as well as on the hoses leading to the brake fluid reservoir and the slave cylinder.
If you keep your foot pressed fully on the clutch pedal for 5 minutes, the clutch will remain perfectly disengaged, and the pedal will return to its normal position.

Today I bled the clutch, but after driving for 5km without using the clutch pedal, it was almost fully depressed again and wouldn't return completely.

Has anyone ever experienced this before, where the system draws air without any apparent cause? What about the seals on the hose between the donor and receiver, are they known to become hard?

Best regards, Rainer.

The initially proposed approach, which involved having a local workshop carry out the repairs, was rejected.

After some people were on vacation, others didn't have time, and the remaining workshop told me, with a clutch kit costing 5 times the usual price, that they didn't want to do the job, I decided to do it myself.

And if I have to dig a hole under the car, and the hoses get in the way.

First, the parts that make sense to replace anyway will be exchanged, such as the clutch master cylinder up to the transmission. If that's good, great. Otherwise, the rest will also be replaced. For the total price mentioned, I would have to work for many weeks to have anything left over.

Hi Rainer,
If there's a leak to the outside, you would lose brake fluid. Can either of the pistons, in the master cylinder or the slave cylinder, occasionally become completely free?
hg
Herbert.

Hello Herbert,

"What surprises me is that while the brake fluid reservoir wasn't completely full, I couldn't find any brake fluid anywhere (where it shouldn't be)."

Sure, but if things go wrong, it will leak out of the clutch bell housing, and the engine cover will prevent it from dripping onto the floor.

To me, it feels like the master cylinder is passing internally. When I bled the system at the slave cylinder connection, air bubbles also came out.

Best regards, Rainer.

Hi Rainer,
See also here for information on bleeding (removing air):
/viewtopic.php?t=30562&highlight=brake fluid

There must be enough fluid in the chamber that connects to the clutch.

The clutch slave cylinder may be removable for visual inspection with the hose still attached.

My suspicion would be that the inlet on the slave cylinder is not sealing properly during clutch operation.

hg
Herbert.

Quote:

There must be enough fluid in the chamber that connects to the clutch.

"Thank you! I had some doubts about that when the error appeared. However, it's possible that the fluid level decreased due to wear on the lining after a few kilometers, but was still within the acceptable range."

It certainly wasn't helpful that I had to brake sharply several times in quick succession just before the error occurred, due to traffic conditions. This likely caused the fluid in the reservoir to slosh forward, and at the same time, the clutch was engaged.

Okay, I'll be the giver now.

Thank you for your feedback!

My brother has a workshop that's somewhat set up near you; feel free to contact him if you're interested. I'll send you his number via private message.

Hi!

Yes, always replace the donor cylinder first, especially with such unusual problems.
That's the fastest way, and it's the cheapest.
and often the cause as well.

"I'm experiencing the same issue on my 8PA Quattro."
It would be great if it were that "easy" to solve.

Unfortunately, the master cylinder was faulty (leaking).

Okay, so it's probably the gearbox, damn, I'd really like to avoid that.