Just sharing. Just got the Bronco on the road and the brakes were dragging real bad. Symptom, come to a stop and then go to take off and it was like I was still holding down on the pedal. I could reach down with my foot and pull the pedal up and the brakes would release.
I removed the master cylinder, took it apart and found the inner most plunger sticking. I force it to pop out with compressed air into the line hole. It had gunk on it. I had mistakenly (lazily) left the master cylinder laying around for years waiting for me to complete the body. And I had put fluid in it at one time, then later stripped the body down and laid everything on a shelf.
Luckily cleaning the plunger and cylinder, bleeding and adjusting the plunger at the booster has fixed the brakes. Have plenty of pedal and it isn't sticking down anymore.
I did do a booster test. I think a valid test is, with engine off, pump the brakes several times and then hold. Now start the engine. The pedal should drop some and that means the booster is OK. I also verified the booster check valve was working. Kind of narrowed it to the master cylinder.
The plunger assembly on the right was the one all gummed up. This pic is after I did some cleaning.
Installed and ready to go.
I removed the master cylinder, took it apart and found the inner most plunger sticking. I force it to pop out with compressed air into the line hole. It had gunk on it. I had mistakenly (lazily) left the master cylinder laying around for years waiting for me to complete the body. And I had put fluid in it at one time, then later stripped the body down and laid everything on a shelf.
Luckily cleaning the plunger and cylinder, bleeding and adjusting the plunger at the booster has fixed the brakes. Have plenty of pedal and it isn't sticking down anymore.
I did do a booster test. I think a valid test is, with engine off, pump the brakes several times and then hold. Now start the engine. The pedal should drop some and that means the booster is OK. I also verified the booster check valve was working. Kind of narrowed it to the master cylinder.
The plunger assembly on the right was the one all gummed up. This pic is after I did some cleaning.
Installed and ready to go.
