My 99 xj sport 4.0 likes to about 210 on the hwy and higher in the city. If I let it idle it will go even higher. It has a 180 thermo and has been flushed. All hoses have been dissconected and heater core, block and radiator have all been thoroughly cleaned. Removed belt and spun water pump it seems tight and functional. The fan clutch seems to be tight as well. There has been no coolant boiling out yet. Yesterday when it went over 210 in idle I turned the heater on and that seemed to bring the temp down but not below 210. When I bought the jeep the cooling system had the consistancy of muddy rust and smelled foul so I assumed that it had a leak at one time and never got flushed. I would like to figure out what the problem is here so any suggestions would be greatly appreciated.

 

You have flushed the entire system? So your sure there is no clogs? Partial clogs?

 

How much above 210 does your Jeep run? As long as it isn't running above 240 you should be fine. I've got a '00, and I run 210 on the dot, and my fan comes on about 215-218. ( I Believe)

 

Sounds like some serious neglect by the PO. No amount of flushing will remove scaly build-up inside a radiator. The t-stat could be stuck, not opening fully if all crudded up. Fan clutch could be bad, the spin test tells little. For +/-$200 u can replace the rad, water pump, fan clutch, etc. The coolant should remain green/clear, if not keep flushing 'til it does.

 

i re did my 90 and got a lower T stat . before that mine would run at 210 and if i went wheelling or just sat in stop and go traffic my fan would kick on at 230 . i changed my t stat to 180 degree which now is a lot better plus i flushed my system

 

I think I might have a bad fan clutch. I got it up to and shut it off and the fan took quite awhile to stop spinning. Im not sure about xj's but on normal vehicles the fan shouldnt make more than 2 or 3 turns at most.

 

 

This sounds like pretty normal operation to me. When you drive there is air flowing through the radiator and it does the work of the fan. When you are idle the fan has to kick on to compensate. It should only kick on at 213 or 215. Nobody's jeep only sits at idle without heating up. When you hear these guys tell you they run at 210 that is while driving. At idle these engines heat up and the fan kicks on to cool the fluid. Your temp guage will move up and down. I know most new cars like my wife's 06 Grand Cherokee will sit still at 180 and not budge. They are programed to do that. Once you breach the 220 range and the fan is not kicking on, or your temp rising while driving on the highway is when you have to worry.

 

 

210 is normal 4.0L operation temp.

does your e fan work? let it get up to 210, then unplug the temp sensor and see if the fan comes on

 

I would agree that the guage is going to be roughly in the 210 area. I made some modifications to my system and in the future will make a few more to keep it down.

Having said that, it does run hotter when your wheeling or stopped for long periods -normal operation-

Do some research, I know there are several threads about cooling system, radiator, clutch fan swaps etc. This I found to be seriously helpful being a novice to alot of Jeep.

 

you could always do the washer cowl induction, or cut some vents in the hood

 

I got my new 3 core rad n today. Let the heep idle at temp for about 30 minutes and it never hit 210 probly ran about 190.

 

Your location? Ambient temp?

 

South Texas about 85 but it would hit 210 when was 67 outside and no ac on