Audi A4 Avant 1.9 TDi - Brake problems Audi A4 B6 1.9TDI

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Thu 3 Oct 2019 09:48
Audi A4 Avant 1.9 TDi - Brake problems Audi A4 B6 1.9TDI - Owen341

So after recently having new discs and pads, I have found that the N/S front calliper is a little sticky and gets very hot after a few miles on an A road drive. It got to the point where after about 5 mins up the motorway the steering wheel began to judder, and even more so after braking.

the other day with a few people in the car and on a hot day I lost all braking power with a spongy pedal. Brake fluid was over flowing from the reservoir.

I took the car to my local mechanic who stripped the callipers, degreased and bled them. Everything seemed to be fine until it happened again with the wobbly steering and worser braking.

With a suspected warped disc (brand new pagid), I opted to go for a new set of discs and a refurbed calliper. I drove the car again for about 10 miles up dual carriage way and a little bit of B roads. I understand that new discs and pads get hot but this was ridiculous compared to the O/S which was luke warm.

The next stage having agreed with my mechanic is to see how they bed in over the weekend, to no avail.

I have looked through the cars history, and have noticed that it has had issues with the same front N/S brakes before. This will be the 3rd calliper it's had.

The car is partial service history, 2003 with 53k miles. (yes 53k miles).

Has anyone had any similar experiences or could offer a solution?

I have got to the point where I intend to swap out the master cylinder and servo. Ive checked the battery tray which sometimes fills with water and that seems to be clear.

cheers,

Owen

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Thu 3 Oct 2019 10:55
Audi A4 Avant 1.9 TDi - Brake problems Audi A4 B6 1.9TDI - elekie&a/c doctor
A servo or master cylinder fault would affect more than one wheel. Possible faults could be with the flexi hose to the calliper , or I have seen abs units cause this problem .
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Thu 3 Oct 2019 13:18
Audi A4 Avant 1.9 TDi - Brake problems Audi A4 B6 1.9TDI - edlithgow

Don't understand the battery tray bit but it doesn't SOUND relevant.

I'm told internal breakdown in hose linings can produce a situation where it acts as a non-return flap valve (like those in veins, I suppose) which causes the brake to lock on.

Wet brake fluid would easily boil in that situation..

I'm a bit surprised if dry fluid boiled quite as dramatically as you describe (overlowing fluid, etc) since when I had boiling fluid it didn't do that.

I'd do a complete brake fluid change (I'd guess the recent work implies that but I'd confirm it,)

IF the L and R brake hoses are interchangeable I'd swap them, otherwise I'd put a new one on the affected side.

No experience with ABS and don't much want any.

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