Bleeding Clutch Hydraulic System (02-06-2004, 8:04)

Hello!
"I'm having problems with the clutch hydraulics on my B4 TDI 1Z, manufactured in 02/93. It seems like air is accumulating in the lines and cylinders after some time. When the engine is cold, there's a lot of jerking when starting."
I've also bled the clutch multiple times, which provides relief for 1-2 months. However, I haven't been able to find any leaks – brake fluid isn't leaking anywhere. But if brake fluid isn't leaking anywhere, then air can't be getting in anywhere, or
I hope someone can give me some advice.

Best regards, Wolfi.

Have you bled the master and slave cylinders?
How did you bleed the brakes? Did you use a hose connected between the brake caliper and the master cylinder? Or did a workshop use a pressure-generating device on the brake fluid reservoir to do it?

Yes, that's exactly what I did – I used a hose between the brake caliper and the slave cylinder. It was a bit of a makeshift solution, but it worked for a while.
According to my understanding, is the donor and receiver cylinder bled during this process, or not?

No! You have to bleed the two cylinders separately. However, the master cylinder can be bled this way, without using that complicated mechanism. But this bleeding method isn't precise. There's still a chance that a small amount of air could remain in the system.

Yes, but if a small amount remains, that doesn't explain why the clutch then worked for 2 months...

Hello,

The brake fluid level in the reservoir should always be kept above the connection point for the clutch. I have already experienced this phenomenon twice, where the clutch pedal completely collapsed due to a low fluid level (but not below the minimum). Workshops often like to sell a completely new clutch in such cases .

Best regards,
Albrecht.

Hello everyone!

Unfortunately, my problem is starting again .

@Albrecht
The brake fluid level was definitely not the problem.

For troubleshooting:
I'm going to try replacing the bleed valve now.

@joergs
Here's the translation:

"How precise is the procedure for bleeding the brakes? Building up pressure on the brake fluid reservoir wouldn't be a problem; I could probably rig something up."
BUT:
Since the lower connections of the two cylinders are connected, wouldn't I need to bleed the system in both directions?
"Or would the flow of liquid be sufficient to draw in air if I create an opening in the brake fluid reservoir?"

Hello - where are the professional mechanics?

Can anyone tell me the procedure for bleeding the clutch using a pressure bleeding device connected to the brake fluid reservoir?
Do I need to vent it in both directions?

I can't really say much about it, but I'll read up on it, maybe I'll find something. I haven't encountered that problem before... but I'll check it out tonight!

hello wolfi_b,

In the standard 'midnight screws' books, there's nothing detailed about it. Besides a mention of workshop work and specialized tools, they don't go into any further detail. Maybe someone has access to the Elsa documentation and can provide you with more information.

Sorry!

Are people already failing to bleed the clutch here?

Bleeding is only performed at the slave cylinder on the transmission.
Connect the device to the BFK pressure vessel. Apply a pressure of approximately 1-2 bar.
"Open the valve on the cylinder after approximately 20-60 seconds (you may need to move the pedal back and forth a few times). Then, close the valve. Usually, bleeding the system doesn't do anything because the clutch system is self-bleeding as long as it's working properly."

In 90% of clutch failures, the master cylinder located at the pedal is defective.
Most often, the problem occurs when the pedal sinks forward and doesn't return to its original position. Bleeding the system can help, but usually only for a short time.

MFG Farni.

Yes, I've been waiting for this!

Thank you very much .

Hello everyone!
Yesterday, I went to the mechanic and wanted to buy a distributor shaft. However, it costs 150€, and there's no gasket set available, so I decided not to buy it (Besides, I don't even know if it's really the problem).
What kind of seals are installed there? I hope I can find replacements somewhere and simply replace them.
Has anyone ever done this before?

Best regards, Wolfi.

Okay, so it finally happened: this weekend I installed a new clutch. It was a lot of work, but it was worth it.
The clutch is working wonderfully , it's easy to depress, offers good control, and doesn't jerk at all anymore. Apparently, it wasn't the hydraulics after all.
However, I'm still wondering about the root cause because there's no visible defect on the old clutch. It's possible that the torsion springs were to blame, as they can be easily twisted by hand. Apparently, the preload has decreased.
Well, I hope this stays like this and the plucking doesn't start again.