97widerider

Hi, I have a 1974 L48. The brake lines were replaced about 10 years ago and new brakes were put on about 3. New master cylinder as well at that time. The brakes have been performing great until just recently. I take the car out at least once a month to get the fluids moving. Last week I get in and the brake metal is very mushy. No brakes. The brake light comes on.

I check the master cylinder and the chamber closest to the brake power booster is empty. The front chamber has only about 1/3 fluid in it. I trace the lines and can't see any leakage anywhere. I take the tires off and can't see fluid anywhere thinking I might have a busted seal.

Since I don't see any obvious signs of a leak, could the brake power booster be bad. Can fluid leak back into it and that is possibly where it has gone ?

Any insight is appreciated folks.

74modified

The vacuum booster just makes it easier to push, the brakes would still work, but would be hard to push. The leak is somewhere in your system, and yes the rear of the master can leak into the booster. Put fluid in and operate until you find the leak. But the booster has nothing to do with the leak.

Jud Chapin

For sure fluid is leaking somewhere. As mentioned, flll the m/c, work the pedal, and check for leaks, particular at the calipers, although the leak could be anywhere in the system. Your leak could be small but just going on for some time until eventually the m/c level got low enuf to where it started pumping air, resulting in no brakes. As you probably know, these cars, particularly the calipers, are known for leaking, especially when they sit a lot.