Jelly in brake fluid

[smg1138]

While I was installing new brake pads the other day I noticed a jelly like substance in the brake fluid reservoir. Anybody know what this is about? I'm using Motul RBF600 right now, but had the stock fluid before. This Motul fluid is around 9 months old and has been used mostly for street and AutoX. I've never seen this before, so any feedback would be appreciated.

[Ultramaroon]

way overfilled. Don't know if that contributed.

[smg1138]

Originally Posted by Ultramaroon

way overfilled. Don't know if that contributed.

No, the photos were taken right after installing the new pads. That caused the fluid to overflow into the reservoir. It's back to normal level now.

[Ultramaroon]

Originally Posted by smg1138

No, the photos were taken right after installing the new pads. That caused the fluid to overflow into the reservoir. It's back to normal level now.

The only time I've seen gelatinous accumulation was the result of leaving E85 sit in a fuel system not designed for it. Is it possible ethanol got in there somehow?

[smg1138]

Originally Posted by Ultramaroon

The only time I've seen gelatinous accumulation was the result of leaving E85 sit in a fuel system not designed for it. Is it possible ethanol got in there somehow?

Since the weather got warm I've been using E85 most of the time. But, how would that affect the brake fluid? Doesn't seem like it could be related.

[Ultramaroon]

Originally Posted by smg1138

Since the weather got warm I've been using E85 most of the time. But, how would that affect the brake fluid? Doesn't seem like it could be related.

It won't be unless somehow your brake fluid was contaminated with it. Do you see any contamination down in your reservoir, or is it just in your fill strainer?

[Swagopopotamus]

I've seen something like this happen when someone mixed dot 5 which is silicone based and dot 5.1 or dot 4 which is glycol based.

Not sure what the car comes with, but if you added the wrong fluid be ready to flush the whole system.


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[Ultramaroon]

Originally Posted by Swagopopotamus

I've seen something like this happen when someone mixed dot 5 which is silicone based and dot 5.1 or dot 4 which is glycol based.

Not sure what the car comes with, but if you added the wrong fluid be ready to flush the whole system.


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I just googled and came up with this exact explanation - mixing silicon-based with glycol-based formulas. Not saying that's it but...

[smg1138]

I've never used DOT 5 brake fluid in this car. I believe the stock brake fluid is DOT 3 and the Motul fluid is DOT 4. To my knowlege, DOT 3, 4 and 5.1 are all compatible, correct?

[CCJ]

Originally Posted by smg1138

I've never used DOT 5 brake fluid in this car. I believe the stock brake fluid is DOT 3 and the Motul fluid is DOT 4. To my knowlege, DOT 3, 4 and 5.1 are all compatible, correct?

http://www.stoptech.com/technical-su...rs/brake-fluid

[Shankenstein]

As CCJ's link states, DOT4 will more readily absorb water and other contaminants than DOT3 (which is probably what our cars came with). Also, it's worth noting that most tech sheets for brake fluids (like Valvoline, Castrol, ATE, Motul, etc) recommend that you are careful to avoid mixing different fluids. The chemical differences between DOT3, 4, and 5.1 won't make them immiscible, but if you are tracking the car... the weakest fluid will degrade first.

I wouldn't worry about it too much. Scoop the goo, pull the fluid from the reservoir using a turkey baster or similar syringe, then thoroughly flush the system. If you have access to a powerful vacuum bleeder, I'm guessing that it would help move any gelled fluid stuck in the system.

Racing brake fluid is only intended to be in the system for a year or two... so if you're an infrequent racer (like me), it's best to flush the system for the first big event of each season.

Also, if you're car is seeing cold weather (significantly below freezing), it can cause gelling. Usually the viscosity returns to normal, but some chemicals separate and misbehave at very low temperatures. My company uses plenty of epoxies and industrial coatings, and some have warnings "Throw away if it sees freezing temperatures." because of the separation issues cause permanent changes that lead to clogged dispense nozzles or inconsistent curing.

[renfield90]

It's caught by your screen filter. It could just be dirt or something that's jelled up. If the fluid deeper inside is jelly-free I wouldn't worry.

[Swagopopotamus]

Originally Posted by Norville Rogers

E85 in the hydraulic braking system? Good tip from someone who didn't know that replacing brake pads will cause the brake fluid to rise.

Maybe he added ethanol to increase the octane rating of his brake fluid.

[smg1138]

Just wanted to post an update on this. I flushed the Motul RBF600 and replaced it with Castrol SRF. The jelly appears to have completely gone away now. Still have no idea what caused the Motul to do that.