Master Cylinder, Slave Cylinder, or Clutch Failure??

mwc360

Member
Joined
Jun 30, 2013
Location
Littleton, CO
TDI
2005.5 Jetta TDI, 2009 Jetta TDI
Hi,

I need help diagnosing a clutch issue. 2005.5 Jetta TDI (BRM)

Symptoms:
-When it's cold the clutch pedal will occasionally engage far too soon or even right (this then causes the car to stall right away). I can then pull the pedal up from the floor or 1/2 way start the car again and everything works fine. Sometimes it starts fine but the clutch just engages too soon (this goes away after the car warms up).
-The clutch used to shift very rough out of 1st gear but since flushing the clutch/brake fluid this week the clutch shifts much smoother...so much so that I am no longer considering replacing the clutch (I previously thought I had DMF problems)
-When I bled the clutch fluid from the slave clyinder value (I think that was the spot) there was a good amount of air that came out and that area was even a bit wet already so there may be a possible leak somewhere which I am monitoring.
-In the 40K miles that I've had this car (145K currently) the clutch has always been very soft. My wife has a 2009 TDi and the clutch pedal is much harder to press in (more comparable to every other manual i've driven).
-Lastly the clutch pedal is very squeaky, at least with the car off (I don't notice it while driving)

Right now It sounds like it needs a new master clyinder but after scouring the interwebs I am not as sure as I'd like to be.

Anyone have any idea what needs to be done?

Thanks!
 
Last edited:

Henrick

Top Post Dawg
Joined
Aug 24, 2010
Location
Ireland
TDI
Golf VI TDI, 77 kW (CAYC)
I think those parts are cheap enough and are not worth that hard troubleshooting.
If I were you, I would replace both, master and slave cylinders with SACHS branded units (this if the supplier of SC and MC for your car to VW factory).

I would ensure two things are done:
-both of the cylinders are bench bleeded before installation;
-power bleeder is used after installation. Install the Master and Slave cylinders (don't forget the new seals - those need to be ordered separately at VW dealership). Hook up the power bleeder to 10-11 PSI. Open the bleed screw and let ~150-200 ml of the fluid out. Then go to the cabin (power bleeder still attached and bleed screw crack opened) and press the clutch pedal back and forth for 20-25 times. Let another 100 ml of fluid to pour out. Close the bleed screw, disconnect the power bleeded, remove excess brake fluid from the reservoir. Go for a test drive, check operation.

I had tough/rough shifting on my Mk5 Golf at similar to yours mileage. It seemed that the clutch was not completely releasing. I ended up replacing both of the cylinders and the problem disappeared. I don't know which one was faulty but I suspect if I had identified the bad one, another one would fail soon also, resulting in car downtime and additional $$$ paid to the garage for the very same procedure to be repeated...
 

mwc360

Member
Joined
Jun 30, 2013
Location
Littleton, CO
TDI
2005.5 Jetta TDI, 2009 Jetta TDI

Henrick

Top Post Dawg
Joined
Aug 24, 2010
Location
Ireland
TDI
Golf VI TDI, 77 kW (CAYC)
No, I did not replace any hydraulic lines. They were not damaged or leaking and looked just fine. I found the exact replacement for master/slave cylinders in SACHS catalogue and it was direct replacement, the very same part which was in the car...

I think I have consufed you when I mentioned replacing the "seal". It is not the inner seals I was referring to - it is actually o-rings between the clutch lines and the cylinders.
 

Henrick

Top Post Dawg
Joined
Aug 24, 2010
Location
Ireland
TDI
Golf VI TDI, 77 kW (CAYC)
Yep, seems to be those!
Visit your local dealership and ask for a discount on those.
 

arneeche

Veteran Member
Joined
Mar 15, 2011
Location
Oklahoma
TDI
2006 Jetta TDI (former), 2012 Jetta TDI (Former), 2014 JSW TDI
If you replace the clutch master cylinder you do so from the engine bay. After you disconnect the hydraulic hose and hydraulic line you will be able to forcefully turn it to the left and it will disengage from the clutch pedal assembly, then it can be pulled towards the front of the car. I would advise you to replace the clutch hydraulic line as well because of revisions done by vw have changed the shape of the o-rings at the ends and the sockets on the slave and master cylinders. I attempted to just buy the o-ring kit but could not get it to seal. I purchased this http://www.idparts.com/clutch-hydraulic-line-a5-brm-p-4413.html and didn't have any leaks after install.
 

arneeche

Veteran Member
Joined
Mar 15, 2011
Location
Oklahoma
TDI
2006 Jetta TDI (former), 2012 Jetta TDI (Former), 2014 JSW TDI
Guess no one had an answer for me. So I found the answer myself and here it is.
The new Master and Slave Clutch cylinder, if you have to replace them. You will also need a new hydraulic line. Since there have been 5 revisions according to the parts guy, the old hydraulic line will not work. Don't bother to buy the seal kit with old lines. It will leak.
Here are the new parts:
Master Clutch Cylinder: 1K0-721-388-AB
Slave Clutch Cylinder : 1K0-721-261-Q
New Hydraulic Line: 1K1-721-465-AQ
this is what I ordered
 
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