NorthIdahoyota

For awhile now my brakes have been acting kind of funny. sometimes it feels like there is a leak in the system. The first time it happened I thought I must have busted a line, but could not find leaking fluid anywhere. After 2 more stops brakes came back to normal. Now maybe one stop in 50 the brakes do the same thing. The pedal goes loose and I have to push it in way farther to stop. It has been a couple months now and I havent lost any brake fluid. I thought it could be air in the system but it goes away pretty quickly!? Anybody have any ideas? help would be appreciated. It is not too big of a deal but I would like to fix it before it gets worse

ksti

Sounds like your master cylinder is starting to bypass, meaning its probably starting to go bad. Your not going to lose enough fluid to notice. Check where its bolted at power unit to see if its sweating some fluid, you may not see it or you can loosen nuts and pull it back and see if there is leakage around piston.

NorthIdahoyota

I loosened the nuts and all is dry behind the cylinder, but your explaination does make sense. Can a master cylinder be cheaply rebuilt or should I start looking for one at junkyards?

Stu Pidasso

One time I actually had a set of braided lines blow out. Problem was they blew out internally. This means that the teflon diaphram ruptured but the rubber coating over the steel mesh retained the fluid. A similar thing can happen with a master cylinder where the rings or seals around the piston wear down and you get blow by within the valve body of the master cylinder. I say replace it and while you are at it upgrade it to a 1" diameter unit. Score yourself a 35$ vac pump and have at it.

5runner

^^^ that is true and/or it could be bypassing internally and not leaking out