I have an 88' 535is with a reoccurring problem... the brakes will become stuck on. The pedal will feel very hard and when it does if I touch the brakes, not long afterward the car all by itself will begin adding more and more brake pressure building very quickly, and force me to park the car and let it sit for an hour or so before i may begin normal driving activity. I really need to pin point this brake problem. The pedal sometimes feels very squishy and then of course there's the previously stated problem. I've learned to drive using the brakes very little and it doesn't happen all that much (except of course when i go to pick up a girl for dinner ), anyway this problem began back in February and i took the car replaced all pads and rotors and bled them in the correct order i triple checked. The brakes have never felt "normal" since Ive had my brake work checked and the brakes re- bled, but the problem remains. I'm not sure if it's related but make brake pressure differential switch went out sometime in April pouring out PS fluid almost as fast as i could put it in so of course i replaced that. Again not sure if that could be related just throwing it out there.
I have a terrible feeling its going to be master cylinder related but of course i would like to hear your opinions being far more experienced than I.
One diagnostic test you can try is to chill down the master cylinder with a small improvised ice bag next time you have this brake issue occur. If it quickly releases you will know. http://www.mye28.com/viewtopic.php?t=17831
I felt and visually checked the hoses when i did my brakes, they appeared to be fine but i may replace them just to eliminate that.
When i get my 95 525i back from the shop so i can still get around, ill probably take out the master cylinder and give it a look over. and i will do my best to try the ice thing thanks for the tip. And money isn't an issue right now haha I'm a wild-land firefighter and business is booming.
I had same problem with my e28 528i , first it was little braking from car(when i put in D or R car is not moving),till that car was braking that my discs/rotors became red.I waited 1 hour till brakes cool down then i took auto to my mechanic and i solve that problem by changing master cylinder and also i changed hydroboost because of leakdown of ATF.
Thanks for the input but I'm quite sure its the over heated master cylinder. i plan to replace it here in the near future and get back to you if it was successful... or not.
), anyway this problem began back in February and i took the car replaced all pads and rotors and bled them in the correct order i triple checked. The brakes have never felt "normal" since Ive had my brake work checked and the brakes re- bled, but the problem remains. I'm not sure if it's related but make brake pressure differential switch went out sometime in April pouring out PS fluid almost as fast as i could put it in so of course i replaced that. Again not sure if that could be related just throwing it out there.