Clutch Pedal

[TaximanWsM]

Hi all. I've been having a search around the forum as I find a lot of useful hints and ideas for trying to find the answer to my problem. In this case, I'm not sure if I have the right diagnosis. So what I'm going to do is tell you the symptoms and things I've tried.

My car is a 2007 B6 Passat 2.0 TDI with a 6 speed manual gearbox and a BKP engine. Clutch replaced 10 months ago. It is used mainly for Private Hire Taxi work.

Symptom: Clutch pedal goes past half way point with pressure only in the last 1/3 of total travel. This has got to this point gradually over the last 2-3 months. Until 2 days ago, I could just get into gear and drive, Once the car warmed up a little, the clutch pedal travel was better but still mostly below half way point. On the odd occasion it did fully returning up on the return spring, but not full pressure from the top of the travel.

I have tried bleeding the clutch slave cylinder from the bleed nipple using a couple of improvised methods.
1. Glass jar with small pipe and half full of new brake fluid. Opened up the bleed valve, pushed clutch pedal to the floor, closed valve and pulled the pedal back up. I have also tried this method without closing the valve but slowly pushing and returning the pedal by hand, with a pause between each push and pull (each cycle taking about 20 seconds). Have not been able to see air bubbles, but dirty and cloudy fluid is seen coming out of the pipe into the new fluid when I returned to close the valve off. Using this method I have filled a 500ml glass bottle with dirty fluid (About 1/2 of which would be dirty old fluid) and have the bottom 1/3 of the clutch giving me some pressure .

2. Syringe. Using an unused printer cartridge refill syringe and the same piece of pipe on the bleed valve. with the pipe full of clean fluid, open the bleed valve, pull up on the syringe creating a vacuum and hold until fluid and tiny air bubbles stop moving, and air is in the syringe. Close the valve and release the syringe which slowly returns down under suction. I then removed the syringe and discarded the tiny bit of air and fluid left in the syringe, into another glass jar. Mostly it is tiny bubbles (like champagne bubbles and smaller coming through. On the odd occasion there was a few large bubbles (1-2 inches in the pipe). This still only gives me the same amount of clutch pedal travel (bottom 1/3), as the previous method.

I should add that all through this attempt at bleeding, the reservoir level has not moved and is slightly up above to the max mark.

My main question is do I need to bleed the clutch master cylinder, and if this is possible, how?

[micheal balbrig]

I do not have answer to your question,but is it possible the problem may be at
clutch pedal arrangement/linkage rod.
The pedal on the A3 has a weak point which sometimes breaks,not sure if Passat is same.

[TaximanWsM]

Thanks for your reply. I'm pretty sure it's not that as I am getting limited success. Using the syringe to vacuum out the bubbles is taking some time but there seems to be a very tiny improvement in the height at which I feel pressure in the pedal...


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[zollaf]

was the concentric slave cylinder replaced at the same time as the clutch. you dont just get air in unless there is a fault or a leak has allowed the resevoir to empty thus allowing air in.. the dirty fluid you mention leads me to beleive no new csc was fitted and this is where the problem is.

[TaximanWsM]

I don't think a new CSC was fitted. You are probably quite right that is where the problem lies, I'm just hoping I can get the car working until new year.

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[zollaf]

do you have any signs of fluid leaking out the bottom of the bellhousing.

[TaximanWsM]

I don't appear to be losing any fluid. Reservoir has not lost any and no sign of a leak...

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[TaximanWsM]

UPDATE #1.
Have managed to get about 60-70% pressured pedal movement back, gears engage as normal and have driven the car around the block.

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[TaximanWsM]

UPDATE #2.
Have given the car a little run around (about 10 miles). All OK at the moment. I would say I have at least 75% pressured pedal movement now.

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[RichardSEL]

How many miles? When was system fluid last flushed out completely and changed for new?
That should've been done when you had your work done IMO as the dirty fluid you mention
indicates system's contaminated.

Every two years is the regime as the fluid turn into water and damage the
steel surfaces of what ever it touches.

Fluid is not DOT4 but VW 501 14-B 000 750. Bleeding should include the ABS pump

As you're removing more and more air from the system, and hopefully what you're seeing
in your jar gets more and more clean watch to see whether your brake operation and
clutch doesn't return to lower travel and other conditions too. As you're in your car for
a lot of the day, you'll notice this faster than other occasional users will