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View Full Version : Thermostat Replacement in a Jeep XJ



Brody
September 15th, 2009, 03:10 AM
While I was dealing with the remaining work on the gaskets on the 84, LaDawn calls with an overheating problem on the XJ. Says that the gauge pegs when she accelerates, but holds steady at idle.

Anyway, long story short, the thermostat was shot. When I pulled the top hoses, they were dry...As anyone knows who has worked on the Jeep inline 6s, especially the ones in the 90s XJs, there isn't a lot of working room. I took a look at where the T stat is and the bolt location. I had the serpentine belt running directly in front of the lower (and hardest to reach) bolt.

Checked the manual to see if there was a "special" way/sequence to remove this. I found "Remove the two bolts, paying special attention to how the T stat is located in the engine block. Replace the gasket and the T stat and reconnect all hose, checking for leaks." Nice...

It looked as though I was going to have to take the fan shroud off to access it, but this also meant that I would first have to remove the fan with the shroud on, yada, yada. After a little more dicking around, I found that loosening the idler pulley allowed just enough slack in the fan belt to force a socket over the lowest bolt. Still no room to work, but just enough to get the bolts off and on and replace the T stat.

Anyway, I hope this saves someone a little grief.

billsbar
September 15th, 2009, 09:25 AM
did it cure the problem? I had the same issue with a 90 Cherokee, but it turned out to be the coolant bottle and cap no longer held pressure. I figured that out AFTER replacing the T-stat

Brody
September 15th, 2009, 09:56 AM
Yeah, it is really happy right now. We did put a new radiator cap on it, too.

I had to do something to my 91 Cherokee that involved taking out the radiator. By the time I was done, I had about 20 assorted metric, SAE, torx, phillips nuts and bolts in all different sizes...You can almost take apart a Yota with a 10, 12, 14, 17, and 19mm...

Interesting on the coolant cap...

Whitey Jr
September 15th, 2009, 04:41 PM
im having a similar issue but its at idle that it gets hot and anything 55+ mph it starts to get warm. i have a new radiator and new thermostat and all hoses the last thing in the line i can chage is the water pump

billsbar
September 15th, 2009, 05:20 PM
better check your cap and bottle, if ones bad buy them both

Whitey Jr
September 15th, 2009, 05:21 PM
i have a new cap i will check into the bottle and see if that does anything

Hypoid
September 16th, 2009, 07:24 PM
better check your cap and bottle, if ones bad buy them both
I think that is on '87 to '90 Cherokees only.

Hypoid
September 16th, 2009, 07:26 PM
im having a similar issue but its at idle that it gets hot and anything 55+ mph it starts to get warm. i have a new radiator and new thermostat and all hoses the last thing in the line i can chage is the water pump
Ummmm, how about the fan clutch???

porkchop
September 16th, 2009, 08:12 PM
im having a similar issue but its at idle that it gets hot and anything 55+ mph it starts to get warm. i have a new radiator and new thermostat and all hoses the last thing in the line i can chage is the water pump
i had a problem with my cherokee geting hot at hiway speeds and at idle and it turned out to be the catilitic converter it was really cloged untill i went wheeling then it started a rattle then driving down the road it blew chunks out my tail pipe now my jeep is really loud (no muffeler eather) and the over heating problem is gone although i do have a different set up with the bottles my cherokee has an over fill tank seperate from the whole system i think the reason why they changed it is because that system wasnt well designed because it was an earlier pressurized bottle design the down fall i suffer is the fact that the antifreeze in my over fill tank just sits there and gets old ive heard of alot of people who switch to the system i have because its much easier to deal with when bleeding the system and tends to be less problematic but i have no experiance dealing with the system you have

billsbar
September 16th, 2009, 09:15 PM
I think that is on '87 to '90 Cherokees only.

it could be I don't know all that much about them, It would be what ever years they used the bottle and cap as the rad. cap and the cap on the bottle as the rad. cap and thats what holds the pressure.


lol now talk about typing in a circle.