340 coolant trouble

67ragtop said
No guages so far. Sorry, it took me so long to reply. Blew the top hose but it was old. Put a new hose on and it overheated and bubbled up through the uncapped radiator. Pulled the new thermostat and put another new one in just in case. Still bubbled up through the uncapped radiator. Pulled the thermostat to see if the radiator would show some flow. Burned the coating off my brand new 700.00 dollar tti headers.

Bummer. Good thing it didn't get you. That could have been real bad. When their hot it'll puke it out like that when you pop the cap. You need to try to run it with the cap off and get all the air out of the system and see how it does. It won't build up pressure like that with the cap off either. Unless something is really bad wrong with it.

Do you have a coolant system pressure tester or know someone that has one you can borrow? If you get one you can pressurize the system cold and see if it's bleeding down internally. That would indicate a cracked block, head or blown/leaky head gasket. If it pressurizes OK you probably just have a stubborn air pocket in it you need to get bled out.