I've got a 1998 Blazer, it started running hot today. It got up around 240 before I noticed it and pulled into AutoZone. I've got plenty of coolant, no leaks. So I went in and bought a new thermostat, replaced it and it's still running hot,..so I pulled it out and I'm now running with no thermostat, and it's still running hot. I can run the heater and get it to drop to about 180 or so. Any clues to what would be causing this problem?? I appreciate any help in advance!

 

You have plenty of coolant, but overheating. Coolant may not be moving. If thats the case, water pumps make the coolant move. That would be the first place I would look, followed next by a clogged radiator. How many miles on your 98?

 

It's got about 130,000. I noticed last night after I posted this that the coolant didn't seem to be circulating. Water pump would make sense,...guess i'll give that a go.