i was driving my merv and my buddys rustler crashed into the side of it, the black esc heatsink came loose and one of the fins is bend, do you need any special kind of glue to regleu the heatsink back to the esc?
and can i colour the esc with a black marker ?
People normally use a thermal paste that helps glue the heatsink to the motor. I'm not sure of any brands but it shouldn't be too hard to get an answer here or at an auto store.
If you mean the casing, I don't see why not, won't affect performance or cooling at all. It might not last because any kind of marker isn't perfectly permanent.
Years ago my son had that happen to a Mamba Max ESC he had in his Rustler. I used a thermal epoxy I had left over from a computer mod I had done. It worked well and the ESC lived for many more years. Mind you there is a difference between what some call thermal paste which is really a thermal grease and has no bonding ability and thermal epoxy. If you go to buy some make sure what you are buying has bonding ability.