I had an old Peugeot 504 station wagon that had a blown head gasket - the compression would build to the point that the lower radiator hose blew - funny thing is that it would still run fine, just start overheating as the radiator level dropped. Changing out the head gasket fixed the problem and as far as I know the thing is still running (it's been almost 20 years). The gasket blew somewhere between Spartanberg and Knoxville - I think I still ran about 60 miles with it blown and it didn't significantly hurt the motor. Of course that Peugeot motor was like something out of a farming tractor and that might have had something to do with it.

-- John