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thermostat, coolant, radiator ... need help


NAXJA Forum User
Recently took a trip to the lake and while driving on the highway, my thermostat was way into the red just under 260... on the way back ... same thing!?! Keeps overheating. I wired my electric fan to a switch, so in the city i do not have problems with it ovrheating. what could be causeing this? and what can i do to fix this... i need to be able to drive the jeep on the highway without any problems. Any advice, similar situations, or words will help .... thanks
Well, how many miles are on your Jeep? Is the auxiliary fan working? It should come on when the temp is over 210* or when the A/C is turned on. How is the fan clutch on the engine driven fan? It should stop VERY quickly if you spin it with your hand. If those are both working properly, pull the radiator and have it checked out by a radiator shop. XJ radiators seem to last somewhere around 120K miles before needing to be replaced. If it needs replacing, get a two or three core replacement radiator that has steel tanks (not the plastic tanks that come on the stock radiator).
Have you checked you radiator for clogged fins -- externally? A few weeks ago a guy showed up at the meeting place for a trail ride complaining that he had overheated on the way there. We were in a parking lot in front of an Advance Auto, so he went inside to buy a thermostat and gasket. Since he had left his hood up, a couple of us were looking at the situation. He claimed his radiator was clean, and from the front it was. However, from the engine side it was packed with mud. I estimate he was getting about 15% air flow.
Eagles right, you might have 'stuff' on the exterior clogging your fins. check to see if their clean. if that dont help do a good engine flush, depending on how old you radiator is you can use the ultra flush (takes total of about 3 hrs of driving avrg 2-3 days) that really flushes all the gunk out! if you have a old radiator use the one that you have to run for like 10 min and flush it with water after. If you go with the strong stuff, you might poke a hole in your rad.

If that dont help you might either have a bad radiator or a bad water pump. its not really worth repairing radiators these days, I got a brand new aluminum 2 core from VALEO for $100 its really quality stuff (DO NOT GET GO DAN RADS, THEY ARE SH|T, I REPEAT SH|T) get a new thermostat too, the wouldnt hurt

I had high temps a while back, (really high temps) but when the eninge reved over 3k the temp started going down, changed waterpump did flush everything was A OK!

P.S. recommend you get that fixed ASAP, your motor not gonna like it if it runs 260* for long, eventually the gaskets gonna go...
well the radiator has 153000 miles on it so its probably hjust bad, i checked the clutch fan, just had it replaced a while back and everythings else seems fine... more infor on vVALEO please... need to get this in the bag
I have been fighting the overheating monster for a year and a half.

I did the prestone flush, new radiator, thermostat, thermostat housing, g.d.i. 2 core radiator, hoses, electric fan, checked all the sensors, flowkooler water pump, and probably more that I can't remember.

I finally gave up and took it to a shop.

They did a block check first to rule out anything major.

next they sent out the radiator to have it flow tested. it tested at only 60% capacity.

I don't know if it was plugged form the beginning, but I do know that I will test any radiator BEFORE installing it, in the future.

they have not put it all back together yet, but they are going to flush the engine without the radiator being connected.

also they said the thermostat would not open but I don't know about that. it may have been an intermittent thing.

they are also going to do a flow rate test on the complete system.
what about the 3 core from 800radiators? there was a NAXJA deal on them at one time as well iirc....

karmirXJ....what's up with the Dana Diamond, you work for em or just a fan? My dad works for em in Indiana

mac '95 marginally overheating monster' gyvr
(If i had to pick 4 free between a fully custom 9" or junk D44, guess what ill go with. might sound stupid but thats just me)

BTW: 3 core is from GODAN, if you hear 'GoDan' run far away as fast as you can...