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Old 06-14-2020, 01:30 PM   #1
Mini-Skoolie
 
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Brake fluid spilling out from underneath master cylinder!

Hey all, getting a little frustrated with the current brake situation. Maybe you could lend a hand.

Since my master cylinder was empty, today I was going to refill the lines, locate the leak, fix it, drain it, refill it and bleed the air. Simple enough I guess.

However, when I was attempting to bleed the passenger side rear brake, no fluid came through when the brakes were pumped and the bleeder valve was opened. BUT when looking at the engine while the brakes were being pumped, there was a MASSIVE leak underneath the master cylinder. (The part directly underneath, not sure what it’s called!) Like, fluid was basically just spilling out.

Bad gasket was my first thought, but there actually isn’t a gasket. And when I removed the brake lines and the mounting screws to the master cylinder, the attached photo is what I was confronted with.

Not sure what to make of it. It almost appears it was designed to leak in this way. (I know it’s not) And because there’s no gasket, I’m not sure what I can do to fix it. It all seems to be in order, but it’s leaking like mad.

I’m sure you will see what I mean.

Photos all uploaded sideways for some reason!
Attached Thumbnails
986CCA55-39C4-445A-AB69-F5C55EAC1E17.jpg   CA9AB928-2B5C-4ACC-8A73-ED6AA13BCCB7.jpg   0E024E2E-B3E2-456B-9561-DC659D357924.jpg  

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Old 06-14-2020, 01:59 PM   #2
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Going more from your words than pix but --
Are you saying the source of the leak if from the piston (held in place with a snap-ring) in the center of pic #2 ?

If "yes", then your source is the piston seals/cups which supply your brake pressure. You can either rebuild the master cylinder yourself or buy a rebuilt m/c. If you've never rebuilt hydraulic parts (in a rare moment for me) I'm gonna discourage you from rebuilding it yourself. Remanned m/c's are usually pretty cheap and will have a warranty...
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Old 06-14-2020, 06:40 PM   #3
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master brake cylinder

This needs a rebuild. by you or some one. Or buy a brand new one. but you may have other brake problems from sitting if this master has been bad for a while..... It is common to have happen....

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Old 06-14-2020, 09:58 PM   #4
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Third vote for master cylinder. The thing it is attached to is the booster, it does not have fluid(brake fluid) in it. Looks like it might be a hydraulic booster, if so it gets pressure from the power steering pump usually. Picture is not enough to really tell though. Still the master cylinder is the problem.
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Old 06-14-2020, 10:09 PM   #5
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Quote:
Originally Posted by Ronnie View Post
Third vote for master cylinder. The thing it is attached to is the booster, it does not have fluid(brake fluid) in it. Looks like it might be a hydraulic booster, if so it gets pressure from the power steering pump usually. Picture is not enough to really tell though. Still the master cylinder is the problem.
Which brings up another point: IF it's a vacuum booster and the hydraulic fluid got into it... The diaphragm seals in a vacuum booster aren't compatible with dot 3 or dot 4 hydraulic fluid. If the boosters been sitting contaminated with hydro fluid I would replace it as well.
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