CrisPDuk

As above, I've got a problem whereby the brakes bite initially, the pedal disappears to the floor, and the brakes come back at the end of the peadals stroke

The car is a 2000 Mk4 Golf PD130 diesel.


PS. The rear pads & disc have just been replaced, and there is no evidence of fluid leakage anywhere on the car.

Andy M3

I would take it to a dealer ASAP - sounds pretty serious.

Dracoro

problem with the hydraulics. a pipe leaking or split etc. maybe. Either way DON'T drive it and get a mechanic to looks at it before you kill yourself.

CrisPDuk

As I stated in my original post, there is no evidence of fluid leakage anywhere on the car. When the pedal reaches the end of it's throw the brakes are there in full, they will pull the car up all square on a pretty steep hill. My suspicion is that there is either a leak in the vac circuit somewhere or the servo is in the process of failing, but I would like the opinion of someone with a bit more knowledge of these things.

BTW the local VW main dealer enjoys what you might call a reputation in these parts, and it ain't good

ALi-B

iTrader: (1)

You don't have to be leaking fluid to have duff hydraulics: Blown seals in the master cylinder being the most likely - which is what I'd put my money on, or sticky non-return to the reservior.

Or the rare possibility of a fault with the ABS/EBD valve block (leaking internally or sticky valve)

If it was vacuum, you'd have a rock solid pedal.

The car is likely to have brake assist, so it'll probably be triggered at the bottom of the pedal travel, which will cut in the pressure pump and bring back your brakes.

ALi-B

iTrader: (1)

Just had a second thought:

What happens if you pump the pedal - does the pedal travel become less or still the same?

If it improves the brakes, then possibly a problem with the pads getting knocked back off the disc (warped discs, loose wheels, loose brake calipers or a duff wheel bearing). Also air in the brake lines can do that too.

CrisPDuk

If you pump the pedal it becomes firm at the top again, but falls away if you keep your foot on. All pads & discs are new, the problem happens when the car is rolling or still, so rotating parts are not a cause. The pedal stays at the top if the engine is not running, which again makes me think servo related, but I don't know enough about modern over-sensored VAG stuff to start pulling bits off *****-nilly.

Kieran_Burns

iTrader: (1)

pop over to http://www.uk-mkivs.net/forum/ - and ask there... they're a good bunch and should help you sharpish... but I reckon it's master cylinder as said above...

awd wrx

I think you will find that they had a re-call for this problem , check to see that yours was done

CrisPDuk

Cheers Kieran, I've been over and asked

Not much response, but 4 times out of 5 I can't even find my own thread, so I'm not surprised nobody's answered

It's forums like theirs that make you realise how well set-up scoobynet is