overheating when worked - AUSJEEPOFFROAD.COM Jeep News Australia and New Zealand

wranglertj · #1 17-10-2009

Was wondering if anyone has some answers on why my JK maybe overheating when under load.
I have given the radiator a very good clean as i know mud in radiator is a potential issue so this doesnt seem to be the cause.
On my last trip on a day that was no more than 22 degrees going up a long incline (quite steep) and was in low range second and doing no more than 2000rpm i was watching the temp gauge steadily climb until the light came on dash warning of high temp (in which case i stopped and let it cool down).
Also, when towing a camper and working the motor going up a steep hill on the road the temp gauge climbed to two thirds and when over the hill it eventually came back to normal operating temp.
Generally however it always stays on just below half under normal operating conditions but when the motor is worked it starts to creep and continues to rise until the motor is allowed to stop working so hard.
In my opinion this is not normal but suspect a dodgy thermo fan as we ended up overiding the low fan speed so when fan is required it automatically flicked to high speed but in all honesty it still struggled under load so there is an issue there somewhere.
Can anyone shed some light on what maybe the cause or if you have had similar issues
Thanks

davidd · #2 17-10-2009

is this an auto? if so it is the same old slush box problem. fit a transmission cooler and the problem will go away. heaps of people have had it and it is standard on any auto whether 2wd or 4wd. if the vehicle is to be worked under high load conditions a transmission cooler must be fitted.

wranglertj · #3 17-10-2009

wish it was that easy David, no it is a manaul...so maybe it will be easier

TassieMav · #4 17-10-2009

I would be checking Thermo Fans, is it a Petrol or a CRD? I remember reading some prior threads of those with a Petrol who found they had overheating issues caused by the fans cutting out due to electrical faults (they are not sealed units). Seems that would be the issue, particularly at low speeds.

davidd · #5 17-10-2009

rubicon ,so a petrol. the vehicle is too young to have internal problems, so i'm guessing fan problems. you have a main fan and i think a secondary fan. you'll have to have them both checked i guess. if not that i have no idea mate. other than that a thermostat problem, but that would show up under any conditions i think. good luck.

DizzyDi · #6 17-10-2009

Been having the same problem for a few weeks, albeit in a TJ - it appeared as though it was overheating but everytime I pulled over & checked, everything was fine & cool. Had a new sensor put in yesterday & all's fine now after rigorous testing on highway & offroad today.

wranglertj · #7 17-10-2009

thanks. I think also thermo fan is the issue but only the one fan that has 2 operating speeds.
It is definately overheating as i can hear the coolent boiling.