Jump to content

overheating problem or bad gauge

Recommended Posts

I just replaced the t-stat and my MJ is still overheating. The coolant is now reaching the radiator (before the radiator stayed cold but its heating up now). I think there may be air in the system but I don't know how to burp it. I'm trying to find the coolant temp sensor to let the air out but I don't know where it is on the engine. I have a 2.5 L. Any help would be greatly aqppreciated.

Link to comment
Share on other sites

What else have you looked at?


Simply replacing a t-stat might fix an overheating problem. There are so many other things that can be causing overheating.


Clogged heater core - restricted coolant flow

Fan clutch not working properly - air flow

Water pump - coolant flow


Air in system

Low coolant

Clogged or restricted radiator


Bad head gasket - worst case


You'd do well to do some more troubleshooting. There's alot of knowledge on this forum, keep looking.

Link to comment
Share on other sites

I decided to convert the cooling system to open.


Bought a new 92 3 row radiator from radiator barn, got here overnight $160. Old radiator looked to be original. I removed the t-stat and put the housing back on, flushed the whole system with CLR and got a butt load of rust and crap out of the system. Heater core looks relatively newish so after pulling all the old hoses off, I flushed the HC separately and got even more rusty crap out of it.


New water pump, junkyard 92 t-stat housing (to install a petcock bleeder), e-fan from a 96 GC (wired through e-fan relay to switch since there is no bung in the new radiator for the temp switch), all new hoses (bypassed and removed heater control valve). Total cost for everything but the radiator was $100. So now I have a brand new cooling system.


Yes, $260 seems kind of steep but not when you consider that it already needed at least a new radiator. Now it gets up to 200, hasn't gone past 210 in 200 miles of up, down, slow and go or on the freeway at 70. Heater works great.


I do plan on spending alot on this Jeep, both time AND money. On to the oil leaks.

Link to comment
Share on other sites

Thanks for the replies guys. We did find the CTS, its not near where the Chilton's book said. Tried burping and everything seemed to go alright but still overheating according to the gauge.


So today I got hold of a infrared thermometer to check if the engine was really overheating or the gauge was lying to me. I let the engine idle for about 10 minutes and drove it around the neighborhood a couple times. Here's what the thermometer read when I pointed it around the engine:


Coolant Temperature Sensor: 200*

Housing over the thermostat: 178*

Water Pump: 180*

Top of the radiator: 152*

Bottom of the radiator: 58*


Given that I'd say I'm not overheating. Also I pulled the wire from the CTS and the gauge only dropped to ~160* (from ~235*), the needle should have dropped to the bottom of the gauge (100*) right? Looks like a bad gauge. What do you guys think?

Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

  • Create New...