new master cylinder leaking

Post by **cpldavis37** » Mon Apr 16, 2012 12:14 pm

Hey guys just got my bronco back on the road after doing the brakes. The problem is my new master cylinder is leaking from the cap. I read that if you put a piece of 3/8 line on the fastener that would tighten it up. Tried it and it is still leaking. Should I just take it out and exchange it or is there another fix?

Post by **akaFrankCastle** » Mon Apr 16, 2012 4:20 pm

Mine isn't so much leaking as it is vomiting brake fluid out the top. So I'm definitely watching to see what answers you get on this.

Viperwolf1 · Post by **Viperwolf1** » Mon Apr 16, 2012 5:03 pm

Those rubber gaskets don't always follow the contour of the mc well. When I take mine off I have to move the top around a little to find the sweet sealing spot.

Post by **Gunnibronco** » Mon Apr 16, 2012 6:01 pm

Long before I went to h-boost, I installed a vac power boost set up and my m/c lid leaked for years. I bought a new gasket from Napa (probably) and put it on, stopped leaking. I felt kinda silly for letting it leak for so long.

Post by **Kinder** » Mon Apr 16, 2012 7:58 pm

May be a silly idea, but have you checked to see if the surfaces are even with a straight edge or if there is a nick in any of the mating surfaces?

Post by **cpldavis37** » Tue Apr 17, 2012 10:11 am

I'll check to see if its level I didnt see any chips if cracks though.

Post by **Lila76** » Wed Apr 25, 2012 7:43 pm

Mine does it too. Especially after wheelin.

Post by **Jesus_man** » Thu Apr 26, 2012 7:32 am

Mine did too. I took my ball-peen hammer and put a small bend in the rod between the humps to tighten it up. Worked for me, but looks like what you tried should have worked too.

My guess is something wrong with the MC. There should be very little pressure inside the bowls to push fluid out.

Post by **99f250** » Thu Apr 26, 2012 11:14 am

Not to hijack, but Chandlars has original master cylinder on it and I want to replace it. What has everyone used? Not planning any hydro or assist, just master cylinder.
Thanks!

Post by **Justin** » Thu Apr 26, 2012 1:00 pm

I'd go with a stock M/C from the parts store.

Post by **Jesus_man** » Thu Apr 26, 2012 1:02 pm

Jeff - what setup does he have? Disc's?

Post by **99f250** » Fri Apr 27, 2012 10:17 am

Discs on front (two weeks old now) and drums on the rear. No proportion valve

Post by **Justin** » Fri Apr 27, 2012 5:12 pm

This doesn't really affect the M/C, but if you really hit the brakes, do you lock up the front or rear first?

Post by **99f250** » Fri Apr 27, 2012 8:19 pm

Rears will lock up first. You can tell that the fronts are pulling about 60-70% of the work though. That's on a dead slam/mash of the pedal.

Post by **Justin** » Fri Apr 27, 2012 8:46 pm

I'd go with a stock M/C and add a proportioning valve at the same time. An adjustable one would allow you to better dial that ratio. Ideally you want to have the fronts lock up first, but that can be hard to accomplish on a vehicle with a big contact patch and lots of weight up high to shift around.

Post by **99f250** » Sat Apr 28, 2012 6:36 am

Thanks. I initially was going with a valve but seems there were mixed opinions on it. Decided to try first and see. Can't hurt to try :)

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