3 Buick LeSabre, 4 wheel drum power brakes, 401 cid.
Here is whats happening. With the car off, the pedal is frozen all the way to the floor, and I can tell the brakes are engaged, because you can't push the car in neutral. With the car idling, the pedal is still frozen to the floor- You can pull it up by hand, but it's really hard and when you let go it's quickly sucked back to the floor. Now with it idling, when the vacuum line to the booster is disconnected, the pedal shoots back up into the normal position- until you press it down again with your foot- it goes down normal and actually feels like a good pedal, but then stays stuck to the floor again. I initially suspected the booster or mc, but was kind of hoping that after doing a whole brake job, the problem would go away.
I replaced all four wheel cylinders, all three brake hoses, the rear brake line, and thoroughly bled the system of all old fluid. The fluid is now a clear steady stream. Still no brakes. There are no leaks anywhere.
I've talked to a few people, and some think it's the booster, but others say its the mc. I also think it's the booster, but both are expensive, so I only want to replace what I need to.
Also, how can I test the check valve? There is a 3 way valve on top of the booster, which accepts vacuum form the intake on one side, and the other side has a line that I can trace into some kind of a canister under the fenderwell- I have no idea what that is or what its for.
So what do you think?