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-   -   Overheating problem (http://www.wranglerforum.com/f282/overheating-problem-182087.html)

Dillonlm09 08-21-2012 09:34 PM

Overheating problem
 
Hey guys I've got an overheating problem on my 02 tj. I just did a coolant flush filled everything back up and now it's overheating. When I left the house the temp was at 210 and I drove about 3/4 of a mile and it had jumped into the red!! I'm thinking it's either air in the system or the t-stat. You guys have any pointers or maybe some tips for getting air out of the system? Any help would be greatly appreciated THANKS

coyote99 08-21-2012 09:46 PM

It could be a number of issues, Thermostat is the easiest solution. Driving it around should cycle the coolant and the level should drop allowing you to add more coolant. Otherwise, I added a back flush kit which includes a tee fitting added into the heater return hose, an added benefit is that when left open while filling it prevents you getting those air pockets. If it overheats while idling and driving under 35 then it could be the fan clutch. It could also be the water pump but generally the leak out the weep hole if not operating correctly.

jherrington 08-21-2012 09:48 PM

yeah, wait till the engine is cool, take the top off the radiator and turn on the engine. this will release the air, fill radiator accordingly. do NOT fill the coolant container where you usually put coolant, put it directly into the radiator. be carefull not to get burned.

coyote99 08-21-2012 09:51 PM

Be careful with the overheating depending on the year, my 2000 with 0331 cylinder head cracked after overheating once. They are known for this. My thermostat went causing the overheating. After replacing, my coolant kept dropping after driving which I thought was air pockets, but turned out after refilling three gallons worth, I had cracked the cylinder head. If I were you I would rent a coolant system pressure tester from autozone or the like and test the system. It's easy to do and easy assurance against blown head gasket or cracked head due to overheating.

SeVeReDiStOrTiOn 08-21-2012 10:01 PM

Sounds like air in the system since you just did a flush. It's easier to get the air out if the radiator is the highest point of the cooling system...so drive up a curb/steep drive way/ramps or jack up the front end. Turn the heater on and run it until the stat opens...it might take awhile if there's an air pocket around it. Keep the cap off the overflow and be ready to put water in when the stat opens...you should see air bubbles coming up through the overflow too.

Dillonlm09 08-21-2012 10:24 PM

Thanks for the input guys. When I opened the hood and checked the radiator cap it wasn't hot but the top radiator hose was really hot and expanded. Would that be caused by the t-stat not opening?

SeVeReDiStOrTiOn 08-21-2012 10:42 PM

That's just pressure in the sytem...don't remove the cap until you can squeeze the upper hose. Air will be forced into the overflow so there's no reason to remove the cap anyway. If your jeep wasn't overheating before the flush the stat is fine but you have to get the air out. You can only get the air out if the stat is open so you have to run it at idle until it does...holding the rpm's up helps. It'll eventually open but keep an eye on the temp gauge.

Dillonlm09 08-21-2012 10:49 PM

So once the thermostat does open up how do I get the air out?

coyote99 08-21-2012 11:10 PM

You start it cold with the cap off and then let it heat up till the thermostat opens( don't worry it won't build up pressure), this will allow the air to escape and you can refill while it's running and cycling the coolant. Or you can let it escape automatically into the overflow but this takes longer and you can't open up and top off until it cools.

SeVeReDiStOrTiOn 08-21-2012 11:33 PM

I'm not a fan of bleeding with the cap off...it takes forever to heat up, no pressure builds (pressure helps the stat open when there's an air pocket)and the coolant evaporates/boils over.


Quote:

Originally Posted by Dillonlm09 (Post 2710337)
So once the thermostat does open up how do I get the air out?

The air will come out on it's own for the most part. Raising the front-end forces the air to the top of the radiator and out the overflow. You don't have to raise it but it helps.

Dillonlm09 08-22-2012 12:05 AM

Thanks guys I appreciate the help im gonna try and get the air out tomorrow.

jherrington 08-22-2012 12:08 AM

I've done it a few times with the way I posted earlier. It won't take that long. I mean seriously, whats the difference between 5 to 10 min?

grumpyangler 08-22-2012 10:00 AM

I know this may be different but, on my 1990 cherokee I would raise the back end of the Jeep and take the temp sensor off the back driver's side of the head. This allowed the air to bubble out of the sensor port. Once you had just water/coolant you put the sensor back in and were good to go. Of course I also drilled a 1/8th hole in my t-stat (put hole on top when installing). This system had to be filled thru the overflow bottle at the back of the engine bay as the radiator had no where to fill it. Just a thought.

tangofox007 08-22-2012 11:10 AM

Quote:

Originally Posted by Dillonlm09 (Post 2709995)
You guys have any pointers or maybe some tips for getting air out of the system? Any help would be greatly appreciated THANKS

Remove the heater hose at the thermostat housing. Fill radiator until coolant overflow from thermostat housing heater hose nipple. Reinstall heater hose.

Quote:

Originally Posted by SeVeReDiStOrTiOn (Post 2710119)
Turn the heater on and run it until the stat opens...

On vehicles without heater valves, turning the heater ON serves no purpose.

Quote:

Originally Posted by grumpyangler (Post 2711586)
I know this may be different but, on my 1990 cherokee I would raise the back end of the Jeep and take the temp sensor off the back driver's side of the head.

The "back of the head" temp senders were extinct before the first TJ rolled off the line.


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