Brakes Problem, Loss Of Vacuum?

[B@rnstormer]

Hello,

 

Few days ago the brake warning light started flashing (only sometimes) and beeping at me. The red warning light/handbrake warning light.

 

I checked the brake fluid level and it was at minimum. I've topped it up this morning and thought that would sort it and in a way it did, no light and no beeping, but I've noticed something else. When driving along, if I brake, everything works fine. If I break again within the next few seconds, it still works but it feels a bit weaker. If I brake again, it's as though I've lost brake servo assistance and I have to press the pedal very hard to slow down. If I drive along for a while the brakes go back to normal but when I brake again a couple of times (if within the space of a few seconds) I lose servo power again. Basically put, if I pump the brakes a few times I lose servo power.

 

I can't see a brake fluid leak anywhere. I've observed the vacuum line from the brake servo to the vacuum pump (not in great detail at this stage) and it seems to be quite hard if that makes sense, it's a rigid plastic pipe rather than a flexible rubber one, does this sound normal? It goes behind some kind of heat-shield on the bulkhead so it's hard to inspect, then connects to the vacuum pump directly. There's no vacuum reservoir (the round black ball I've seen in pictures and in the Haynes manual).

 

I'm thinking along the lines of the vacuum pump, the servo or the vacuum tube being the cause of the problem. Any experts here who can suggest what I should try first?

 

Thanks,

 

B@rnstormer

[victor meldrew]

I have had the same thing when the master cylinder seal allowed the brake fluid to drain into the servo.

I got a master cylinder from a scrapper and it's been fine since.

If you go down the second hand route make sure to get the right one as there seemed to be quite a few types

[richyrich]

I had exactly the same symptoms - rigid pipe was split where it connected onto an elbow connection at the brake servo. About 46 quid from Fraud,

Hardest part was taking the heat shield off - feeding the pipe along the original route - then the really hardest bit getting the heat shield back in place - b----r of a job. 

 

Good luck

Rich 

[seatkid]

As Richy says check the rigid vacuum pipes for splits, usually at the ends, e.g. at the servo, at the pump or at the joins. Common fault across all VAG models due to poor plastic used. Also check the smaller flexible vacuum pipes that feed the turbo control system.

 

You can effect a temporary repair by binding the pipe with amalgamating tape.