Join Date: Dec 2001
Location: Belleville, Illinois
Thanked 22 Times in 17 Posts
DOT 4 glycol brake fluid has a very high boiling point, suitable for disk brake systems that can glow red hot. Of course the calipers aren't that hot, but they wrap around the rotors, and can boil fluid that's been contaminated with water. That would make me skeptical about the exhaust system getting the line hot enough to boil fresh fluid. But it's an easy enough theory to test. Wrap the tube or the exhaust pipe, or both, in some fiberglass insulation, or just push a wad of it between the pipe and the tube. If it cures your problem you've confirmed your theory.
On the subject of mechanical wear, when the system is cold, how far off the floor does the pedal get before the clutch starts to grab? If you have an inch or more, I doubt that there's serious wear in the linkage.