Break Master Cylinder Leak

[zanman]

Hi all - during my initial test drives I noticed a couple drops of break fluid dropping into my driver foot box. I isolated the leak to the rear MC (I have dual setup). I popped the rod boot off and sure enough it had fluid in it and also a strange white gunk. I included a pic for reference. Anyone ever see this and/or have any idea what I’m dealing with here?

Thanks again for the tremendous support.

[zanman]

IMG_6052.jpg

[F500guy]

The white gunk is grease, if you get fluid there in the boot, the seal is leaking or leaked when you first started. seems others have a shared experience in past posts.

[edwardb]

Agree likely the front seal is leaking. I had one do that too on the front brake MC in my Coupe. Upon close examination, the seal had a defect. Probably when it was molded. If a Wilwood, they have rebuild kits that replace everything except the housing for about $30. Easy to install with just a snap ring. The .75" Wilwood that was in my Coupe (from the kit) used Wilwood Master Cylinder Rebuild Kit 260-10514. If something more, e.g. the bore is damaged, a whole new MC is required.

[rich grsc]

The word is brake.

[RoadRacer]

There’s a reason I buy all the unwanted mc’s posted here! Been through a couple of failed ones - you need a spare on the shelf

[Mike.Bray]

There's a reason I changed my master cylinders from Wilwood to Tilton.

[Mike.Bray]

The word is brake.

You always say what I'm thinking to myself Rick!

[Jeff Kleiner]

You always say what I'm thinking to myself Rick!

Wildwood
FF5
castor
breaks
tow in
Hildebrand



Feel free to add more



Jeff

[frankeeski]

Wildwood
FF5
castor
breaks
tow in
Hildebrand



Feel free to add more



Jeff

Picture Alblum


Frank

[SJDave]

One of my 3 Wilwoods leaked, after taking it apart the bore in the cylinder had several voids, air in the casting. The had chewed up the seal.

Replaced it with a Tilton, world of difference in quality, bores are hard anodized, Wilwoods raw aluminum.

[zanman]

Sorry ….brake ……not break! I cleaned it up and it doesn’t seem to be leaking anymore. Is it best to rebuild or replace or just keep an eye on it? Is it possible this leak occurred just during priming? I’m not a fan of ignoring brake line leaks but I also don’t want to rip this apart if not necessary.

[edwardb]

Sorry ….brake ……not break! I cleaned it up and it doesn’t seem to be leaking anymore. Is it best to rebuild or replace or just keep an eye on it? Is it possible this leak occurred just during priming? I’m not a fan of ignoring brake line leaks but I also don’t want to rip this apart if not necessary.

If you think it's possible the leak may have come from a spill during the build (or whatever) then probably OK to go forward. But if it's really leaking, it's not likely to heal itself. During the build it's pretty easy, although a pain I know, to remove the MC and check it out. Way harder once the car is all together. Once you have the MC out, it's literally a single snap ring to pull out the piston, check the seals, etc. If in doubt, I'd be doing that.