2003 Chevy Blazer

Hello,

Have you checked the radiator itself? Look at the fins do they all look in tact and in good shape? Run your finger down or up the fins, do they turn to dust or brake off, if so it is time for a new radiator.

If the above is all good or seems to be. While vehicle is running look in the overflow tank, is it bubbling? Does it smell like exhaust fumes? If so you probably have a blown head gasket. If you don't see any bubbling find the top radiator hose does it feel like it has pressure. Is it easy to squeeze together? If it is wait a couple minutes check again. If the vehicle has not reached normal temp and there is pressure in the coolant system then you still most likely have a blown head gasket.

Post reply and results here.

Well, when you turn the vehicle off it will usually increase in temp by about 5 - 10 degrees before cooling down.

One other question just thought about.

Do you know if you have an Aluminum Head or Not?

If so did you use a Chemical Flush? If so before doing anything else I would reflush the system and use Plain Water. Using a chemical flush in an engine that has an aluminum head and steal block will create an Electrical Current and destroy the gaskets.