overheating problem or bad gauge

[Philistine]

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.

[ParadiseMJ]

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.

[ParadiseMJ]

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.

[STERLING STINGER]

what about parking it on a hill or drilling a small hole in your thermostat?

.....as someone in this forum suggested to me a couple months ago

[AmJay]

On mine I just put in as much antifreeze as I could and let it warm up. Shut it off came back in about 30 minutes and added another gallon and a half. In other words it burped itself.

[freakjeep93]

my dad has bruped his (mine now) 2.5 by letting it warm up with the rad cap loosened up or off. granted ive had eagle tell me that it won't work but id try it .

[Philistine]

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?

[MjAllTheWay]

see what i sed is mess with the gauge pop off that cover and jest push it back thats what i did it works great

[Philistine]

see what i sed is mess with the gauge pop off that cover and jest push it back thats what i did it works great

 

Hey Mark! I didn't know you were on here too! I'm going to try that tomorrow. Just looking for more opinions.

[MjAllTheWay]

ya I'm on hear too i looked for every ware i could get info on my MJ and this is the best place thay will tell you everything u need

[Jeepcom23]

What gauge cluster do you have?

I had the blue gauge cluster with idiot lights, light was coming on, swapped in full cluster, was never over heating.