Brake failure

[tjclemens2]

Hello All. I need some guidance. I was driving my 1985 318i and lost all of my brakes. Some history is that this car was garaged for the last 25 years. I have going through the car, piece by piece and the car seem fairly solid. When I lost my brakes, it came out of nowhere. I saw no “blow outs at the calipers. Reservoir was full. My question is what could cause this? Faulty master cylinder that is original? Break booster?? What would cause both front and rear brakes to fail??

[tjclemens2]

Hello All. I need some guidance. I was driving my 1985 318i and lost all of my brakes. Some history is that this car was garaged for the last 25 years. I have going through the car, piece by piece and the car seem fairly solid. When I lost my brakes, it came out of nowhere. I saw no “blow outs at the calipers. Reservoir was full. My question is what could cause this? Faulty master cylinder that is original? Break booster?? What would cause both front and rear brakes to fail??

[reelizmpro]

For all to fail, I would suspect the brake master cylinder. Did the pedal go to the floor?

[MrBurgundy]

Like what was raid above.

Lost of brakes with a full reservoir is either a bad internal seal in the master, that would make the pedal go to the floor.

And

If the booster failed, you'd have the very hard pedal.

[PEZ2]

I would suspect the master cylinder seals have failed.

[Vincenze]

Is there a brake fluid leak somewhere?

I would immediately change the rubber hoses. Then, I would check if any of the solid brake lines are rusted.

A new brake master cylinder isn't expensive https://www.pelicanparts.com/More_In...-1-156-273-INT

[Jaxx_]

Full fluid is a mystery, I would have suspected some to be leaking somewhere. If both front and rear brakes failed, what was the brake pedal feeling like? Did it go to the floor? Was it just hard to push and eventually slowed the car down?


I had both brake cylinders fail in the drums after sitting for some time. Inspect the inside if your rear wheels for fluid. If they are leaking, replace both. The hand brake hardware will be more expensive than the wheel cylinders and you'll likely replace those components too.

[tjclemens2]

Full fluid is a mystery, I would have suspected some to be leaking somewhere. If both front and rear brakes failed, what was the brake pedal feeling like? Did it go to the floor? Was it just hard to push and eventually slowed the car down?


I had both brake cylinders fail in the drums after sitting for some time. Inspect the inside if your rear wheels for fluid. If they are leaking, replace both. The hand brake hardware will be more expensive than the wheel cylinders and you'll likely replace those components too.

So when I was driving breaks lost full pressure and went to the floor. There is no obvious leakage I can see. I have a feeling its the Mastercylinder

[MrBurgundy]

It's the master.. that's where fluid pressure comes from and if the internal seal goes, it will not build any pressure.