Brake fluid leak from caliper

Kamillio

I was at the track the other day. The ambient temp was close to 90F track was at 125-130F (measured).

The car ran fine, no breaking issues anywhere on the track. Once I parked my car and went around to check tire pressures I noticed that I had break fluid leak from the bleeder nut on the caliper. By the time I checked it, it was already all white and sticky (we made a few dirty jokes lol). But on a serious note, nobody knew why this has happened and if it could be some kind of problem!

I did two full days of track days in similar but not as hot temps the weekend before and this has not happened.






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mults

Almost looks like there was some sort of sealant on the bleed valve (like a Teflon product) that got so hot it melted off of the valve threads. Never saw brake fluid that color (unless it turned to foam). What brake fluid are you using?

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Kamillio

You might be right. I use RBF 600. I bled the brakes before myself and never applied any Teflon, etc. though. It's possible someone did it before me?

I just thought maybe the fluid boiled or something and then changed color. I'm quite confused what that was.


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Jhill

Even if the fluid had boiled it should not leak out like that. I think it must have been some Teflon thread sealer leaked out from the threads area. The fluid is sealed from a tapered seat, the threads have nothing to do with sealing the fluid. Sometimes people put a teflon sealer on the threads so when vacuum bleeding you can get a better idea of when all the air is out, without it you can suck air in around the threads and back out the bleeder port, it won't enter the caliper it just makes it hard to judge when all the air is out of the system.

I say clean it off and see how the pedal feels. The fluid your using should be sufficient for track use I would think.

BGTV8

Man - you have been beating on the brakes that hard that the caliper sh1t itself ............

Spooler

That is normal in high temps for our stock calipers to poop out the bleed valves. It is because of the heat. Whatever pads you are using sure coaked up the rotors. This is why folks install air ducks and/or upgrade to BBK kits for track duty.

Rusty

My calipers will do that to during a trackday. The calipers get hot and expand around where the bleeder valve is. Allowing some brake fluid out. There is another thread on this. This something that our stock 'bono's will do. The rears more then the fronts. Far as I know. There is no way to get the stain off the caliper either.

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RN SHARK

Yup, has happened to mine as well during a track day. Not every time though. Even with cooling ducts and RBF fluid.

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Mike

yeah, the caliper expands when it gets real hot and fluid seeps out around the threads of the bleeders.

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Kamillio

Sorry with the delay of my reply.

Okay sounds like a consensus of calipers expanding around the bleeder valve.

I flushed my brake fluid and it was just fine, didn't cook or burn. Color was almost identical to brand new fluid.

As a side note, my clutch fluid was black...and this is only after 6k miles and 5 track days. Not sure what causes this. Clutch always behaves perfect, synchrorev is a pretty crappy at matching revs on the other hand.

Also, whatever it was that leaked out was super easy to clean off. It was not like you described.


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Jhill

Well enough people are saying this so it must be happening but it really does not make sense because the threads are not what seals the brake fluid in the braking system. If it were like a pipe thread then this would add up as the heat would cause the caliper to expand and then the tapered seal of the threads would loosen up and allow seepage. But the seal on a bleeder to caliper is a tapered seat so unless the seat is getting distorted which would be incredibly hard to do then even if the thread fit got looser the bleeder would have to physically back out for it to leak. Just doesn't add up.

flashgordon

I had the same issue in Monza



with sport package Akebono, Project Mu Pads, RBF600 and stainless tubes....

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Rusty

I know what you're saying. The caliper gets hot enough to distort around the seat. Allowing some fluid past. If you look at the pictures. The heat is traveling from the pistons, straight up to the bleeder area. If the bleeder area was about 1/4" higher or had more meat to the outside of it. We might not be talking about this.

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Jhill

Huh, I guess. Just what a weird issue, never seen that one. Looking at the pick holy crap hot spots all over that rotor lol, must have been pushing it.

Kamillio

I thought those were from the abs kicking in on the rear tires possibly, didn't have those on the front.


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