Several months ago my daughter burned up my 1996 4.0 XJ engine when a freeze plug started leaking and she drove it till it stopped. I got a remanufactered engine and installed it with new water pump, hoses and thermostat. Properly burped the system ( I think). It has tended to run a bit hot in slow going ever since. So I put in a new 3 row radiator (copper/brass from Summit Racing) and a new fan clutch. Still sometimes runs hot when wheeling or in town with A/C on. Go fast and it cools right down. So now I’m thinking about an all electric fan setup from Mishimoto. Is there anything else I can try. I often read that if your getting hot, an e-fan won’t help. But I don’t know what else to try.

 

How's the fan clutch working because I have had new ones not work right , and witch electric fan do you have ? and how good is it working ? and you know a new engine will make more heat .

 

Try a factory MOPAR stat.

 

Is the fan shroud installed and intact?

 

If you go electric, make sure the total CFM is at least 3000. Less and you will not have gained a thing

 

Thermostat seems to be working properly. As does the fan clutch. Shroud is in great condition. Engine now has about 4,000 miles on it. Running water wetter and Pennsoil platinum synthetic oil. At 4,000 miles should the newness of the engine still be a factor?

 

What indications are you getting that it's running hot? If it's the gauge alone they leave a lot to be desired in the way of accuracy. Have you verified the actual coolant temp with an infrared gun at the thermostat housing?

 

when driving at high speeds it runs the gauge pointing just past straight up (220). When hard wheeling it can get close to the red. But then goes back to what I believe is about 220 if I can pick up the speed. What temp should an infrared thermometer show at the thermostat housing if the gauge shows 220? Same as gauge, assuming it works right?

 

If your temp gauge sending unit was located at the t/stat housing and it's reading didn't match or wasn't close to the infrared one I'd of course rely on the infrared reading. But since your gauge sending unit is located at the back of the cylinder head I'd take a reading at both there and the t/stat housing. Also compare the reading at the sending unit with your gauge.

 

The factory setup works just fine even in hot climates. If yours is not, find the problem and fix it, instead of trying to re-engineer the design. We've seen poster after poster here who spent big bucks on fancy components, only to find that none of that solved the problem. Once they fixed the real problem, they were fine.