Coolant vents through pressure cap on Harrison overflow tank. 63 vette
The car runs at 180 - gauge and heat sensor gun confirmed. Sometimes after its parked, the cap on the overflow tank will vent and spittle from the top. The cap is new, and Im on my third new one - so pretty sure its not the cap. Nothing comes out the overflow hose.
Any ideas? Air in system? Radiator re-built not long ago. Car runs fine. This would be after stop and go around town type drive.