[Audi A3/S3] brake problem - advice needed!

[nik_codling]

Hi everyone,

I've got a strange problem with the brakes on my '97 A3 1.6. Last week I discovered I had a leak from the N/S rear banjo bolt union - turned out one or both of the crush washers had corroded, and I was merrily squirting fluid everywhere. I didn't realise this at first until I got a warning sign on the dash telling me the fluid was low.

I immediately checked the fluid and topped it up, and discovred the leak at the back, which by now had got fluid all over the wheel and tyre.

Not long after this, and during my perhaps ill-advised and very careful drive home the pedal went to the floor. That said, the brakes did still work, albeit at a reduce rate. I suspect this was caused by an almost total loss of fluid - I'm not sure if these cars have a safety valve to keep braking on opposing ends of the car, but it was just enough to get me home.

I replaced the faulty washers and cleaned everything up and then attempted to bleed the system. After an hour and around a litre of fluid I was still getting a spongy brake pedal, although the brakes were much improved, and safe enough to drive. I took the car to a local VW/Audi independant, to have them bled.

The garage put around 3-4 litres of fluid through the system by means of a pressurised bleeding kit on the master cylinder reservoir, but it has failed to cure the problem. The brakes still work, but there is a little too much travel on the pedal, and a spongy feel. That said, if I rev the engine the brakes do appear to firm up.

The garage seems to think the problem may be caused by the fluid getting too low, possibly drawing cack in to the ABS unit. I'm not too convinced about that though, as the ABS system still works (I tested it on a quiet road last night).

My suspision is that there could be an air leak in the vacuum hose to the servo, as I noticed when I was bleeding the brakes that the servo (I think) was making a whistling noise which went up and down in pitch as I pumped the pedal. Perhaps even a leak in the servo diaphragm. The vacuum hose theory could be backed up by the fact that the idle is occasionally a bit fluttery, and that the pedal hardness improves if I rev the engine.

I'm at a loss for ideas, and the garage has given up, so I'm hoping someone here might have a clue, or some ideas to check out! Any advice or tips would be really appreciated.

Also, I'd be grateful if you could recommend any independants in the Portsmouth area, so I can get a second opinion.

Nik

PS Sorry for the long post, hope you're still awake!

[nik_codling]

Just pinging it back up to the top again - any tips and advice would be welcome!

Thanks,

Nik

[s3ollie]

sounds like a vacuum leak to me too as the pedel hardens up if you rev the engine.

try jmk.org.uk, an independent garage in portsmouth.

i used them, they seem very professional and knew what they were talking about