Mechanics

VW MASTER CYLINDER ISSUES

1986 Volkswagen GTI • 27,000 miles

It started with one burst brake line in the rear and has snowballed out of control. I have replaced 3 of 4 lines now and bled them to find that I have no pressure behind the pedal. So I have replaced the master cylinder with a referbished one and I am not getting any pressure out of the front two ports. The two lines in the rear are bleeding and the pedal is going right to the floor but the two front lines I get nothing and the pedal comes to a mechanical stop above the floor. It wont go all the way down. Is it a faulty cylinder or is there a possibility that the brake booster has gone on me aswell and doesn't have the umph to move the second piston in the master cylinder?
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Dannygilly2006
November 25, 2011.



Recheck the brake master cylinder for internal leak and also the the brake booster operation-Double check for external leakage

Rasmataz
Nov 25, 2011.
We have looked for leaks around the cylinder. What would be the best way to check the brake booster? Soapy water? We hear air noises when pushing the brake but my friend said it is just the booster in action. He says if the booster isn't working you would never be able to move the piston in the cylinder. Is it possible that the booster has a small leak and is only providing enough assist to move the first piston up to the ports? I have spent hours working on this brake issue and I am not willing to give in.

Tiny
Dannygilly2006
Nov 25, 2011.
Do this pump the brakes a few times hold it in and start the car up, the brake pedal should sink in bit-

Rasmataz
Nov 25, 2011.
Unfortunately I can't do it now because it is at my friends house but we have tried starting the car to see if the vacuum lines would assist it further and nothing. I am going to go with a faulty cylinder. Thanks for your help. We are going to take it out on saturday and have a good look at the cylinder before we return it.

Tiny
Dannygilly2006
Nov 25, 2011.