Brake leak, no signs of fluid leaking anywhere!

[Darbrrats]

I must have a brake leak cuz the fluid keeps running low, but there are no signs of fluid leaking anywere. Is it possible that the bake master cylinder is leaking into the power booster were it cant be seen. Also no fluid on the floor either. I blead all the lines and they worked great for about 2 days, then fluid levels went down, and now i have to pump the brakes to make it stop. Please help

 

[DSMAddicted]

Originally posted by Darbrrats
I must have a brake leak cuz the fluid keeps running low, but there are no signs of fluid leaking anywere. Is it possible that the bake master cylinder is leaking into the power booster were it cant be seen. Also no fluid on the floor either. I blead all the lines and they worked great for about 2 days, then fluid levels went down, and now i have to pump the brakes to make it stop. Please help

Hey Guys, I have the SAME EXACT problem!
On my 1G, I have to top the master cylinder off with brake fluid every 2-3 days because it looses all the fluid and the brake pedal goes on the floor. I've had this problem for a while, I changed my brake system last month (SS lines, 2-piston calipers etc) but I am experiencing the same issue. Can anybody point me in the right direction on where to start checking for leaks of brake fluid?

Thanks in advance,

Walter

 

[Doug99RS]

Pull the master cylinder back away from the brake booster. Check the brake booster for fluid, there should be none. I've seen a lot of trucks have reseviors that "consume" brake fluid only for it to be leaking out of the back side of the master cylinder in to the resevior.

If you've already checked:
Calipers
Brake Lines
Proportioning valve
wheel cylinders (if so equiped)
Brake fluid resevior and resevior (no seal in the cap can cause a leak)
and the hoses going to the resevior

Then the last place I know to check would be the brake booster.
Doug

 

[DSMAddicted]

Doug, thanks so much for the advice.
I'll check on this and let you know.

Walter

 

[Darbrrats]

I found the problem. It was the master cylinder leaking on the brake booster, that little seal on the end of the master cylinder that connects to the brake booster. I replaced the master cylinder and all is well.

 

[Doug99RS]

Good find and thanks for the feedback.
Doug