Ramrod062

Head gasket allowing exhaust gasses to enter the cooling system creating over pressure condition and blowing coolant out around the cap. Small enough gasket failure that only gasses can pass under pressure but not coolant so no contamination of oil or coolant. That’s my untested theory at this point anyway. Already r&r intake gaskets. Been down all the paths mentioned. Very nice truck with ~100K. Worth repairing IMO. Guess I’ll test my theory.