how do you know if a brake booster is bad???? (long)

[TJs692002]

So my brakes went south ie. pedal would go to the floor and the car would stop but the pedal would stay in the down position after I let my foot off the pedal. I would have to pull the pedal back towards me to put it back in the resting position in order to use the brakes agian.

So I installed a new master cylinder and pressure bleed the two rear cylinders, and both front calipers then I did the clutch, using almost 1 liter of fluid in the complete bleed process.

Now that the car is back together and the job is finished, I go to test everything and I still have the same problem. Pedal goes to the floor and stays put. I again have to pull the pedal back up off the floor to disengage the brakes. The pedal will not automatically return to it's resting position once it has been depressed to the floor.

My pedal box is nice and clean, I have the spring between the pedal and the bracket and it seems to be working I mean the spring is not broken. Could it be possible the spring has lost it's springyness? I dont know what else to check. Could the Brake booster be causing my problems?

As always....Thanks to all for the ideas, suggestions and help!!

[norm]

Did you change your flex line? I had the same thing on an old 1800. Check the line from the master to the slave.

[TJs692002]

There is no line that goes from master to slave. I have a metal line from the reservoir to the slave and that line is metal. Well except for the first two inches where it attaches to the reservoir. I installed new hoses from the reservoir to master and from reservoir to the metal hose going to the clutch slave. All other parts are the same as before.

[KFunk]

The brake return spring in the pedal box shouldn't matter. Mine was completely broken off, and I drove for like 6 months or more without noticing. The brake pedal still returns to the same position, without the spring.

As for your problem, I really don't know. sorry.

[KFunk]

There is no line that goes from master to slave. I have a metal line from the reservoir to the slave and that line is metal. Well except for the first two inches where it attaches to the reservoir. I installed new hoses from the reservoir to master and from reservoir to the metal hose going to the clutch slave. All other parts are the same as before.

What kind of brake lines do you have going from the reservoir to the master, and the other lil piece going to the metal line for the slave?

The factory ones have cloth on the outside and rubber on the inside. I have no idea why, but if you replaced them with something different, then maybe we've stumbled on the weird reasoning BMW did that.

If you need some of the cloth line, I've got some that you can have. The dealership would only sell it to me by the meter, so I have enough for like 2 cars leftover.

[TJs692002]

I have the factory cloth hose that goes from the reservoir to the master. I also use about 2" of the same hose from the reservoir to a metal pipe that goes down to the clutch master. Its all the stock stuff.

[Guest Anonymous]

I had the same problem with my 1969 Chevrolet Belair with non power 4 wheel drums! I thought it was the master cylinder first, but after I talked to my friends dad he told me to clean out my lines as dirt and crap can build up in there and clog the lines causing not enough pressure to build up to stop the car and thus not bring the brake pedal back up. So, I opened the lines at the wheel cylinders and the master cylinder, and blew compressed air through the lines. Then I installed new rubber brake hoses, and now the car stops on a dime with a very nice firm pedal. Hope this helps, good luck.

-Cyrus

[Brandon]

Hey if you end up needing a brake booster I have about a dozen of them and need to thin my collection...send me an email.

[FL02]

I had to change the booster and MC when my brakes did that. I say find a used booster and install it and you'll probably fix your problem.

[TobyB]

like it's something else. The pedal should drop maybe an inch- at most 2- with the engine idling, and a bit less with the motor stopped.

Do you have the rear brakes adjusted nice and tight?

Changing the rubber high pressure lines is good insurance- and if the back line is acting as a restrictor, that could exacerbate things.

But there should be enough spring in the mc itself to return the pedal- have you taken apart the linkage (there's a TON of it!) and cleaned and greased everything? Every car I've taken apart needed cleaning and greasing, and worked a LOT better afterwards...

hth.

t

[TJs692002]

The main problem is that everything was working perfectly. I parked the car to ride my motorcycle for the summer and while moving the car for the first time in about 2-3 months is when my brake problem happens. The brake pedal does not go all the way to the floor when depressed. I have good pedal feel when depressing the pedal trying to stop. Once the brakes are engaged the pedal just stays put and does not return to it resting positon.

[Guest Anonymous]

I had to change the booster and MC when my brakes did that. I say find a used booster and install it and you'll probably fix your problem.