Quote Originally Posted by Bob Barker View Post
I'm not sure on our trucks (just looked but didn't find anything), but on other cars there is a "high" spot on the cooling system that needs to be burped if the coolant has ever been drained, overheated and pushed into the overflow bottle, or gotten low and been refilled allowing air into the system. Basically what can happen is the air bubble get stuck in the water pump and it will not circulate the coolant through the engine.
FWIW...& it may not be much, A few yrs ago I read about a Rodeo or Trooper owner with similar problems, I believe it was over at Planet Isuzu.

He had to park his truck on some ramps, so that the nose was higher than the rear of the truck to "burp" all the air out of his cooling system.

Might be worth a shot...