I have an '89 200T, When the car gets hot, like after driving an hour on a hot day, The front brakes build up residual pressure in the lines. It gets to the point that its like driving with my foot on the brake. Any ideas what this could be? Master cylinder? Air in the lines?

Thanks

It's a worn out Master Cylinder. As it heats up the piston gets stuck in the bore and you end up with dragging brakes...

I bet if you let your car cool down the brakes work fine, right?

Makes you wonder why Audi would design a radiator fan that sucks hot air out of the radiator and deposits it towards the MC? Surely can't help braking on a hot day IMHO...

Steve Ankney
88 5000
Holland, MI

I vacuum bled the brakes this weekend. I thought maybe old fluid or air in the lines could be the problem (air could expand when hot). Also vacuum bleeding the brakes may dislodge any debris cloging the vent orfice on the MC. If not, then I'll do the MC next weekend. BTW, an old cruise control vacuum pump, a mason jar, and a few fittings and tubes make an awesome vacuum bleed system.

P.S. Your right, it only does it when overly hot.

i have the same problem in my 5k. as far as i can tell, it's actually due to low-heat brake pads, they overheat and swell and force the caliper out. i figured it out when i was driving, and a sprinkler sysytem sprayed on my wheel and the brake violently let go of the disc.

it make my car have two speeds; go (slowly) and stop.

Yes it is. I had the very same problem, I replaced the M/S and the problem is gone. You can get one rather cheaply!