radiator/coolent bottle cap

[darin bell]

Hi everyone,

I have a question regarding the cap on the radiator overflow container. I can tell when it's not sealing good because I get a whistling sound while the engine is under a load. Right now, it's not sealing because I can hear that wistle sound. My question is this: If the cap isn't creating a good seal, will it caust he engine to get hot under a load? Last week on a small family trip with the camper on the truck, I noticed the engine temperature climbing under a load to where the temp warning light came on. I also had the turbo kick off on me and had to turn the truck off and back on to get the turbo to work again. The gauge goes down when it's not under as much stress. The fan seems to be kicking on more than normal as well. I also noticed that it had spit fluid out the cap.

I ask this question because last summer I had a new cap put on before my long trip with the camper and the truck was fine - didn't get hot once and no turbo issues.

I have this theory in my head that if the cap isn't creating a sealed enviroment, it will cause the fluid to boil which may be why it's getting hot and spitting fluid. Is that a false theory?

[m-chan68]

Disconnect the hose that runs from the intake manifold to the degas bottle, at the degas bottle. Start and run the engine to check for water pump flow, from the degas bottle hose. Do you get a steady stream of coolant exiting the hose with the engine running? If not, your water pump impeller is shot. If you do, your head bolts are likely stretched, causing coolant to pressurize under load (which is likely the case if your temperature gauge went into the "red zone" anyways).