why does brake fluid turn black?

[digitaldrifter91]

why does brake fluid get black, like in brake systems and hydrolic clutch systems?
i know one is moisture...but i dont know if thats a direct reason as to why it turns black.

thanks

 

[mph]

I suspect that some of it comes from rubber in the system. We know that master cylinder seals, for example, go bad eventually (both my brake and clutch MC's died recently). It makes sense to me that the rubber ends up somewhere. There was a lot of black, rubbery sludge in my reservoir, too.

 

[MolaKule]

Heat is the third reason. Heat gets transferred to the fluid from the pads and wheel cylinders and the resultant oxidation of the fluid creates a chemical change.

 

[Robbie Alexander]

quote:

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Originally posted by MolaKule:
Heat is the third reason. Heat gets transferred to the fluid from the pads and wheel cylinders and the resultant oxidation of the fluid creates a chemical change.

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Yeah, but how does the heat have a chance to do this?
Most fluids today can handle the heat, it's when the owner does not keep the fluid flushed, that allows the heat to attack the fluid.

Most fluids will fail under extreme loads, heat, etc, after they have been wet, not a normal thing when dry, so I think the lesson is to keep the fluid changed.

Don't let it get wet, that way the fluid will give max. protection. Do this by flushing once a year, because most fluids are wet after this time.