Brake master cylinder leaking from cap.
07-22-2018, 11:37 AM
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Brake master cylinder leaking from cap.
Hello, all. Some months ago, I decided to replace my original master cylinder since it had a slow leak out the rear seal. Prior to that, I had redone everything else in the brake system. After replacing the master, within a week, I noticed brake fluid leaking out the TOP, and running down on the inner fender. Figured it was just a little overfilled, but within a month it had run pretty much to empty. It's only on the front reservoir, the rear one stays up fine. Later, I changed it because I got annoyed with the leak. The new cylinder leaks too. Same exact thing. Have good firm brakes, (When it doesn't run itself out on the front and trip the warning light). Any idea what's going on? Thankfully it's not ruined any paint. I even tried making a second inner gasket to apply more pressure.. no dice. What I don't understand is the original never did that. The truck is a 1985 F-150 with power brakes.
07-22-2018, 02:41 PM
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Post lots of pics: cap on, cap off, where you think the leak originates, various angles...
http://www.supermotors.net/forums/th...-and-or-videos
http://www.supermotors.net/forums/th...-and-or-videos
07-22-2018, 07:17 PM
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Leaks from the literal front of the reservoir, where the cap meets the body. Right up top. No other way to explain it really. I can't even figure how fluid would be able to get up that high as the level works down. But after even a 10 minute drive, it's wet again and dripping down the apron.
07-23-2018, 05:09 PM
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So, you're not going to post pics?
08-06-2018, 02:20 AM
#5
I just had a similar issue after checking my fluid levels... I was able to solve it by removing the diaphragm and cleaning the mating surfaces with a scotch-brite and isopropyl alcohol, then bending the clamp slightly to increase the pressure on the cap.
