Hey all, looking for some insight on a brake issue I’ve been dealing with.

Background: Car gets driven about once a month, mostly track days and autocross. Stainless braided brake lines and calipers are about 5 years old, brake fluid is maybe a year old.

Recently noticed one of my rear calipers was running outrageously hot — caught it during a quick drive around the neighborhood before a track day. Pulled everything apart and found the caliper piston wasn’t retracting properly (slide pins were free, piston could be pushed back in manually).

When I pulled the brake line off the caliper I found a clear gel-like glob sitting inside the hard line fitting, right at the flare seat and inside the caliper. Honestly have no idea what the glob is.

Questions:
1. Anyone seen this gel/jelly substance at a brake line fitting before? What is it? It has the consistency of Vaseline
2. Given the dragging piston with free slide pins, is a worn piston seal the likely culprit? Could this be grease from inside the caliper?







Thanks

 

Silicone sealant? I'm not sure why it's in the line.

 

does kinda look like silicone but also not sure why it would be in there unless maybe it was in there when you got the lines for some reason. That or something got into the brake fluid and is clumping up like that but I am not sure what it would be. I would probably try to flush the system well with good clean fluid. Possibly take the lines loose at the calipers and flush that way first, then re-attach for the final flush and bleed.

 

My bet is the last mechanic put some on the brake line threads for some reason, and it got into the line. All remnants need to be flushed out. It's kinda dangerous sitting in the line.

 

I was the "Mechanic" who installed those brake lines and calipers haha. I really don't think I would have put anything on the threads like that.

I will definitely flush the system out but I would still love to know what happened! My theory at the moment is a piston seal went bad allowing that grease to mix in with the brake fluid but I really have no idea.

 

Normally if the seal fails you see a leak. System is under a lot of pressure so I would expect fluid to come out vs grease to pull into it. But I am also kind of at a loss as to what it is!

 

Any chance dot 5 fluid got mixed in? Dot 4 or lower mixed with 5 = gel

 

They do make brake fitting thread lube. and some may have been used by the caliper manufacturer when installing crossovers. I've seen this kind of gel appear in my power bleeder lines as well after forget to clean my lines as well.

 

It does look like dielectric grease that is used on brakes as well as other threads. This may be a case of more is not as good as less.