Hello everyone. I have been having an issue on my Evo 4 where the clutch fluid goes dark black typically after only one to two hours of driving after replacing and bleeding the fluid. I have no leaks whatsoever in my clutch lines, and have even replaced both the master and slave cylinders, yet still have the same issue. I have tried DOT 3 and DOT 4 fluid. I noticed the DOT 3 seems to last longer than the DOT 4, but still becomes black after some time. It doesn't seem to impact clutch performance, but still is concerning to me. Anyone have any ideas as to why this might be happening?

 

How old are your flex lines at the wheels, it could be rubber deteriorating inside those soft lines, *I'm just speculating, never experienced this before

 

I'd be on the same thought process as RobbieOh. Seems like a rubber line somewhere in the system is deteriorating and causing the blackening.