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01alam
11-04-2010, 09:48 AM
Hi,

I hope you are all well, I have recently experience brake problem with my 1996 2.6.

I was searching on Google and here and all I can find is that the problem affects 2001 on Audi A4's (B6).

Bascially, I was driving down a hill one evening and there were no sudden braking etc. I parked up after that very short journey. Then when I restart the car after 5 minutes, and the first instance I touched on the brakes at the end of that road, the pedal becomes very hard, it feels like its totally pumped up, I tried a few times along that road and it remains the same. Then I turned off the engine, check under the hood (can't be mroe than 2 minutes) opened up the brake fluid reservior, all is well and in the right line there. Then restarted my engine and it drove off fine, brakes felt normally - if anything felt more responsive.

My question is whether anyone experience a similar problem? It wasn't a particularly cold evening and it wasn't raining. It is equipped with ABS, and it is working as I had to do a hard braking the day before this happened. It is fine now, and have not repeated the same "hard pedal" roblem since 4 days ago.

Could anyone please tell me what this could be caused by?

Many Thanks

Peter D
11-04-2010, 10:52 AM
There were two types of servo's in 96. One is a normal Vacuum servo the older is a hydrualic servo and is quite different. You need to check the plenum chamber for retaining water although a 96 version does not have the problem as the later models. I suspect the one way vacuum valve is failing.

If you go to the car first time in the morning, do not start it but test the brakes, if they are solid then if you start the car and the pedal drops then the servo or the vlave is loosing the vacuum overnight.

You need to find the problem as the brakes could be seriuosly reduced in effeciency if you have to break whilst going up hill as the throtle is open and the vacuum in the servo can fade away.

Check behind the master cylinder for the vacuum chamber for the servo.

Regards Peter

01alam
11-04-2010, 11:35 AM
Thanks Peter,

I can confirm when I step on the brake pedal whilst the car is not started, it goes hard and when I start the engine whilst still press the hard brake pedal it goes soft and lower in position (not to bottom). It is actually made in 1995, so I would suspect the old type - which one would that be?

I can also confirm that going down hill, it has fine brakes, but when going up hill as you said it is slower to slow down in speed, but the difference is not great.

So would this likely to be a split pipe or vaccum failing?

Many Thanks

Peter D
11-04-2010, 05:24 PM
Have you got a servo behind tthe master cylinder or not. It is some 10 inches in diameter and 2 1/2 inches thick.

You say it goes hard. How many times can you press on the pedal before it goes hard.

Regards Peter

01alam
12-04-2010, 03:00 PM
Hi there,

I need to press it twice until it goes hard and I can't see a Servo under the hood or under the plastic cover nearer to the windscreen.

It also happened again, seems to be correlated with using reverse??

Many Thanks.

Peter D
12-04-2010, 04:18 PM
So is there just an junk of casting there between the master cylinder and the bulkhead. ? Regards Peter

Peter D
12-04-2010, 04:44 PM
This sounds as though it is the hydraulic type and either the return vlave has failed or the reservoir is duff. How many presses can you get out of it 2 mins after you turn it off. PM me your email address and I send you more information. Regards Peter

01alam
13-04-2010, 10:23 AM
Thanks Peter, I am not really technically gifted, so I have decided to send it into a garage to have a look, thanks for the help though, you have been very helpful.

For information, it is worst when it starts and when the automatic choke is on in the morning, however when it is warm it performs fine.