Running hot on freeway

What could cause my 92 to run so hot? In 10 miles of driving its up to 210. If I am on the freeway I have to turn the heater on high to keep the temps down. I am thinking maybe the thermostat is stuck closed or somthing? Anyway to test it out? Any other opinions?

Thanks
Chris

I am fighting an oveheat bug as well.
Do the electric fans work?
Did u test the gauge?
Test the mech. fan?
How old is the rad.?

frsno jeeper said:

I am fighting an oveheat bug as well.
Do the electric fans work?
Did u test the gauge?
Test the mech. fan?
How old is the rad.?

Click to expand...

See I know its not the fans because the fans do nothing when its on the freeway, the wind is blowing in at over 60+mph thats faster than the fans can pull it in. I am guessing the gauage is correct because the heater is blowing hot as hell air out and the hood feels like I could cook a hamburger on it after a long drive. Now I dont know how old the radiator is, is there a way to tell if its going out? I dont want to drop $100 on a new one and have it still suck..

4.0 engines run between 195 and 220 degrees. Try draining and replacing the coolant see if that will lower the temp a little. But as I said, 210 isn't overheating for a Cherokee. You will know your overheating, usually water boiling out the overflow tank.

bzdel2441 said:

What could cause my 92 to run so hot? In 10 miles of driving its up to 210. If I am on the freeway I have to turn the heater on high to keep the temps down. I am thinking maybe the thermostat is stuck closed or somthing? Anyway to test it out? Any other opinions?

Thanks
Chris

Click to expand...

A t'stat that's stuck closed is a distinct possibility. To ckeck it, here's the procedure:

1. Start engine from cold and leave it at a fast idle.
2. While it's warming up, keep your hand on the upper radiator hose.
3. When the t'stat opens, the hose will suddenly go from being cool and soft to hot and hard.
4. At that point, read the temp. gauge right away.

If the temp. is 210* or above, replace the t'stat. If it's 195*, that's the correct t'stat opening temp. in which case the t'stat is fine.
If the latter applies to you, drain and flush the complete cooling system (including the heater core), then replenish it with fresh coolant using distilled water in a 50/50 mix with anti-freeze. There are radiator flushing agents available that'll remove scale deposits from inside the radiator core.
Replace the radiator cap and also replace any hoses that look old, hard, or cracked.