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Rolly32 05-05-2013 03:38 PM

Is over heating in 4Hi Normal?
Ever since I got my 2003 4.0 l6 TJ, Iv'e notice normal temp is 210. Iv'e noticed that when I engage into 4hi, the temp will slowly climb to about 235. Is this normal to run hot in 4wd? I do not have a transmission cooler but I figured I did not need one since it does not overheat in 2wd. Is this normal?

scott howard 05-05-2013 03:46 PM

no your cooling system should maintain 200-210.
You should flush the system out or have it done and replace your thermostat and see if that fixes it .
if it does not i would replace the water pump.

Jerry Bransford 05-05-2013 03:47 PM

No, that's not normal. Are you running 4Hi where 4Lo might be a better choice? Running 4Hi on steep/difficult terrain can cause the engine to have to work harder than it would if you were to select 4Lo instead.

Rolly32 05-05-2013 03:55 PM

Thanks for the speedy responses gentlemen. :thumb: It sounds like a simple fix. Jerry, believe it or not, I notice this issue while I was on soft sand driving normal. I was not getting stuck or digging myself into the sand. I could have cruised the beach on 2wd but I only engaged into 4hi since I didn't want to put stress on the motor revving at about 4.5-5k when it would be more ideal to just shift into 4hi and cruise at a lower RPM.

After I engage it back into 2wd, I noticed the temp will drop back to 210.

Jerry Bransford 05-05-2013 04:06 PM

In that case, it just sounds like your cooling system's cooling capacity is marginal. That might be fixed by any or a combination of the following... a cooling system flush, new 195 degree thermostat (could be sticking) or it could be that your radiator is becoming clogged with hard water deposits from having used tap water instead of distilled water to mix with the coolant. Could even be that the water pump is going bad.

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