hard pedal

antonsone

Member
79 Scout II 304 stock brakes

hey guys I noticed a week ago that my brake pedal got hard and brake power went down drastically. I took a look at the front end and the pads were about 50% and the rotors were at a close to max. Diameter so not a big worry there. I then checked the rear to find that the pads are gone as in rivets rubbing gone. The drums were maxed out as well. So I rebuilt the rear with all new gear and adjusted them to the "slightly rubbing then back of a few notches". I then bled the system and got a very small amount 1/2 teaspoonish of yellow cloudy fluid from the passenger side rear then good clean fluid after that . . . I still have the same hard pedal low power problem. I know the booster was replaced in early 08. But otherwise I am at a loss as to why the issue "just happened" without any trauma to the brake system other than the pads going down. Any thoughts.
 
Bad booster or booster check valve. Booster check valve is a long shot unless you have very poor idle vacuum.

Most likely a bad booster.
 
A functional test. If it has vacuum at the port but creates no boost force multiplication when pressing on the pedal, it is dead.

Does the truck pull badly or sway the rear right or left when you mash the brake pedal? If not the booster is bad.
 
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