Help Needed Need help locating problems with brakes

[95_stroker]

So, that would mean a booster rebuild or a new one? Is there any way I can check the diaphragm?

Hook a vacuum pump to it while the truck is not running, pull a vacuum and see if it leaks off.

 

[MBRPCrazyford]

ok, I would but i don't have one.

 

[trackspeeder]

ok, I would but i don't have one.

Hit your local auto parts store. They should have one.

 

[MBRPCrazyford]

are they expensive?

 

[95_stroker]

40 bucks or less.

 

[drmjf]

OK here's one. My brake work great. The truck stops on a dime. Here's the problem, if I sit with HARD pedal pressure on the brake, it slowly drifts to almost the floor, but not quite. I never lose brake feel or anything like that, they just slowly drift to the floor. Now, when I let off the pedal and get back on it, the pedal is firm just likeit should be and then it starts going towards the floor again. It's weird. The brakes are bled fine, plenty of fluid. Nothing out of the ordinary. I'm not losing brake fluid anywhere. It's a little strange. Any help would be great. thanks

You could have a bad master cylinder. Leaking between the two sides of the dual cylinder. Normally a bad booster will cause a hard brake pedal. The fluid has to be leaking some where for the pedal to fall to the floor.
Try this test Turn the engine off and pump the pedal about 4 times then hold pressure on it. If it falls you will most likely need a new master cylinder. Hope this helps. Mike

 

[MBRPCrazyford]

OK, I'll try that. Like I said it never goes completely to the floor and I never lose brakes. Kinda weird and it's not usin any brake fluid.

 

[95_stroker]

A bad master cylinder would allow the fluid to leak back into the master reservoir if the seals are bad. So that is a distinct possibility.

 

[MBRPCrazyford]

oh, ok. I gotta go give the pedal pump deal a try.

 

[MBRPCrazyford]

tried the pedal pump. Everything checks out OK.