92 Audi 80 2.3e Brake problems

[casperthefriend]

Hi all,

Hopefully someone can point me in the right direction here, been reading these forums for a while and everyone seems really helpful.

I'm having a problem getting a decent brake pedal on my 80.

So far I've replaced front discs and pads and rear pads and tried to bleed the system. The brakes *work* put require a fair shove to pull the car up. No warning lights are showing and no fluid seems to be leaking.

One thing I have noticed is that the pedal doesn't feel any different whether the engine is running or not - it just feels spongy.

I'm going to try and re bleed the system again this weekend and replace all of the fluid.

Does anyone have any tips on the best way to bleed these cars, and anyone have any ideas on what I should look for?

Maybe feels like there isn't any servo assistance to the brakes, though I've read that B4s have hydraulic assistance???

Confused,

Rob

[zollaf]

does your car have a brake servo? its a round black thing with the master cylinder attatched. if it does, its not working. if it doesnt have a servo, it has the hydraulic assistance, and this isnt working. find out which you have and let us know.

[casperthefriend]

Hi,

It doesn't have a servo pipe that I can see, so it must be hydraulic.

I'm thinking that could well be some air trapped in the system - the car was laid up for 6 months before I bought it.

Am I right in thinking that the pedal should feel different when the engine is running vs off? Haven't had an Audi before but my other cars have a "stiffer" pedal when the engine is off.

I've also read some conflicting advice on the bleeding order - most say furthest to nearest from the MC, but a few say nearest to furthest. Having just done the brakes, the car doesn't have ABS fitted,

My car is a RHD 92 B4 (Australian market), so is the correct bleeding order - rear passenger side, rear driver side, FPS, FDS?

Thanks in advance.

[zollaf]

ok, if there is no servo then it must have the hydraulic system. there will be a resevoir on the passenger side engine bay for the power steering, filled with green hydraulic oil. under and behind this will be a bomb. a handgrenade sized metal sphere, with a pipe running to the master cylinder. if you switch off the engine and pump the brake pedal, you should get about 30 pumps to extinguish the assistance, and as with a servo, the pedal will go hard. there should be only a small movement of the pedal at this stage. if it still feels spongy or has too much travel, theres air in the lines or another problem. now start the car. the pedal should become soft, and youll have a red warning light flashing, until the hydraulic is pressurised. if the pedal remains hard, the problem is possibly with the bomb.

[casperthefriend]

Firstly, thanks for the help so far.

Secondly, I'm an idiot... The car DOES have a vacuum servo.

I found a split in the rigid vacuum line that runs into the servo just under the master cylinder. It had split by the t piece one way valve just to the right of the head.

Luckily I found a replacement vacuum hose at a scrap yard and have fitted that. Instantly my rough idle got a lot better - but unfortunately the brakes are still the same.

The pedal feels no different with the engine on or off, I'm guessing that I still have a problem with my servo???

I will run a brand new rubber vacuum line direct to the servo and block off everything else just to test that it isn't the "new" hose.

Anything else I should look for before I bite the bullet and visit the scrapyard for a replacement servo?

Thanks

Rob

[zollaf]

if there are no other vacuum leaks, it does sound like the servo is broke. the pedal should be hard after a few pumps with the engine off, then go soft when you start.

[casperthefriend]

Hi,

Right, I've narrowed it down to the brake servo - ran a known good vacuum hose straight from the manifold to the servo, hose was definitely pulling a vacuum, but servo not responding. Even tried a little squirt of penetrating oil and a bit of gentle persuasion with a BFH, but nothing...

So, looks like I'm going to have to pull the servo and replace it - looking at my repair manual (Haynes) it suggests that the removal is easy, but looking in the driver's footwell at what I'm supposed to be removing I would beg to differ!

Does anyone have a guide/tips on how to remove a brake servo from a 92 80 2.3?

Thanks

Rob