Brake Leak

[Kevin]

  I found I have a brake leak from the rubber thingie in the center of the right rear caliper. I found it last year replaced the thingie with another one and have the same issue. Anyone have ideas on a fix? The previous owner replaced all the calipers a few years ago being rebuilt I was thinking perhaps the hole could have been bored out too much. Whaddya think, Kevin 

[FieroBUZZ]

If it's where the piston comes out, the seal may not be seated or fubared in some other fashion.

[Kevin]

 No its on the inside of the caliper, the piston seal looks good at least it isn't leaking. It should be yellow or black and about 10mm in diameter. It allows access to the mechanism inside the piston.

[dguy]

You're talking about the thingy in the center of the piston, right?  Looks like a plastic washer or body plug with a line bisecting it?  It's actually a vent, if I remember correctly.

If you're seeing fluid coming from there, it means that the seal behind the vent (inside the piston) has failed.

The rebuild kits which I've purchased for the rear calipers in the past have never included the inner piston seal.  Every other possible seal has been there as well as the vent, but not the seal behind it.  Not surprising though, as to get to that seal I believe that you have to disassemble the piston.

A brief mention in the Ogre's Cave brake article suggests that if the seal behind that vent has failed, then the caliper is scrap.  Would seem to co-incide with my experiences with over-the-counter seal kits.   

[Kevin]

  It is the thingie in the center. Dang. I was afraid it would be something a bit more complicated. Thanks Don.

[aaron88]

My rebuild kit came with all the seals.  Can't remember where I got them.

If you want just the piston seal you could get a front rebuilt kit...wait a sec.  Your brakes are not the same as mine.  Nevermind.