Quote Originally Posted by the godfather View Post
Dam it. Drove for most the day today. Temp went up after about 200km. Check radiator...levels low.
No water in the oil, no steamy exhaust.....mmmm, scratch that head.
Had a hairline crack in my GQ radiator about 10 years ago. Only leaked on the freeway after about 10kms. Would idle all day and night and not lose a drop - took ages to work out where the problem was. Even held up to a pressure test at the radiator place without showing the crack.

Might be something similar?