Hi guys, you all have helped me so much in the past, need some tips again. 1978 F150 4x4 power brakes. It appears the master cylinder is leaking fluid from under the cap. The original was leaking so I replaced it in august 08', refurbed one from autozone, then it started leaking. Replaced it last week, now the new one is leaking. Not alot, but if I go out for a drive and return and check the master cylinder there is fluid hanging from underside of it. The truck is my toy and doesnt get driven much, it is lifted with 33" tires. The last time I replaced it I pulled the booster off and found fluid in it, dumped it all out and started over. I bench bled just as the directions said. I do have speed bleeders at all four tires, and no leaks on any of the fittings. I did keep the fluid level down about 1/4 -3/8" from top rim on the m/c to prevent any spillage. I also read on here about a m/c leaking internally and fluid building up in the front or rear reservoir, but same level in both on mine. Also when I am bleeding the brakes I have the stem pulled out on the front of the proportioning valve. I also backed off the stud in the booster that pushes on the m/c piston. The brakes are firm and the truck stops good. If I wipe off the m/c it stays dry, until next time I drive. It is the original booster havent had a reason yet to replace it, cant see how it could affect the m/c. Any and all tips welcome, thanx in advance guys.

 

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