Water level?

[woody82]

My truck keeps having boil over after I shut it off I have new radiator new head gaskets and heads have been cracked checked The coolant level in the radiator is about 5 inches below the neck and it finally quit boiling out I have put a new thermostat in it never over heats when engine is running.

[dcasalena]

Have you burped the coolant system? Are you sure the thermostat isn't upside down?
Spring side down on the thermostat. Run her for a while with the rad cap off till the thermostat opens and water starts circulating to allow any circulating air pockets to escape through the open radiator.
Simple things and the upside down thermostat is a common mistake.

[davischevy]

I vote for the thermostat.

[FirstOwner69]

Below full is where your coolant level should be without a recovery tank. Here's a link to the other thread you started on this subject.

http://67-72chevytrucks.com/vboard/s...d.php?t=649048

[brown7373]

It is kind of hard to give a definite answer, because you haven't told us anything about the truck, like the year, engine, mods, etc. Should we assume it is an 82, Woody82?, or should we assume it is a 67-72 like this particular forum?

67-72 didn't use a recovery tank, and the correct water level is well below the top of the radiator. Filling to the top will always cause it to be expelled. A recovery tank system needs a different type radiator cap so it can not only let it push out, but also draw it back in. I'm not sure, but I think the tank needs to be at a certain height compared to the cap.