Akitaman

Can the 4.0 be run too cool? I know some vehicles need to reach a certain operating temp to run correctly. My firebird has to be at least 165 before it will go into closed loop operation and stop sucking gas. Does the jeep have a similar setup? I Have a brand new radiator, new pump, and everything does work and cool properly. I just want to keep cool on the trails as well.

So I am thinking about a lower temp t-stat and full electric fans. I dont know whether to wire them up switched or auto, but I do know I want a switch for water crossings so I can turn them off. Anybody seen good results out of doing things this way?

4.3L XJ

Yes, you can run the too cool. They need to run at least at 190 degrees. Below that temp they will run rich and give you poor milage. The up side of that is that they will have a few extra horsepower that way. About 7%

jd4x426

all cars trucks whatevewr are set up to run at specific temp for optimum performance and fuel mileage running a different themostat will alter the pre set temp setting you might not notice it but i wouldnt change it unless you are running way too hot

Akitaman

my last xj met with an untimely end, blew the headgasket because of a bad tstat, and a bad temp guage. Course it was the 4 cylinder too. So I am alittle paranoid about overheating. Especially on a trail.

4.3L XJ

if you are prone to overheating, a lower temp tstat will not save you. You just need to have everything working properly. The biggest thing you can do to help on the 4.0L is to wire the electric fan to be on all the time.

Akitaman

that dosnt over cool it? What about getting rid of the mechanical fan and putting in all electric fans running all the time? That is what I would really like to do, but dont want to overcool and lose mileage, or mess something up.

4.3L XJ

Even better

Akitaman

Cool, Thats what I'll do then. Thanks for the help!

4.3L XJ

Just make sure the fans move enough air. I put two fans on that both move 2000 cfm.