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Overheating, only when driving?

M

mikey333

NAXJA Forum User
Location
Proctor MN
Hello all, new to the xj world! Love the info found here. I have a question I have been trying to fix. My Jeep has a new thermostat, 195 degree, and it also has a junkyard radiator I just put in to replace garbage old one...but jeep is still overheating when I start driving. It idles at right around 195, but then seems to go right up when I start driving. Also, the auxilary fan never goes on? Can that be the problem? What about the waterpump? I have started it and driven around a couple of time to get any air out of the system, but any other solutions would help! Thank you in advance!
 
151000 miles on it, unkown what other work has been done...could the head gasket be bad, or even a cracked head? the oil still looks good...
 
junk yard rad? could have some crap in it? not something i would use as a replacement because.... it prob was junk anyways so that could be it right there. check around water pump and look for coolant leaking. thermostat possibly stuck shut? those are cheap are relatively easy to replace. coolant temp sensor could have crapped out/ not connected right. do you have heat? is the coolant level consistently correct? do you have enough coolant in you system? is the coolant mixed correctly? does your electromagnetic fan work? is the electro fan super easy to spin when jeep is off? this is the primary fan that runs all the time. my 98 aux fan doesn't work either and i have no overheating issues esp in mich winters so im sure that really wouldnt contribute to overheating. my 93 was the same way no aux fan and never over heated ever really.
 
Hey! think I am hopefully an idiot...i started squeezing the hoses and the lower hose is frozen solid! so hopefully this will fix it! still no aux fan...will update when i fugure it out! Thank you again...
 
the lower hose has a giant metal spring in it. the spring prevents the hose from cavitating while the motor is running. sure you don't have "frozen" and spring confused?
 
I hope i don't have spring and frozen confused. i squeezed from the beginning of the hose all the way down it and it felt like ice, with some thick slush, so i am going to try a space heater by it, then in the morning I will see what I got. May have to find a heated garage or something....
 
some things to check:
is your coolant at the proper concentration (not just water and frozen), hows the tention on the serp belt, when was the last time the cooling system was flushed, did you flush the junkyard radiator before installing, have you "burped" the cooling system after the new rad, etc

on my 95 i would see the temp on the guage rise, but the fan wasnt kicking on. it turned out that there was air in the cooling system and would hit the sensors at different times. i burped it several times over a week and no problems since.
 
What's the temp up there? The coolant shouldn't have frozen.

Do the hoses heat up at all? If the engine is running and overheating, but the coolant lines are still frozen, that's an issue.
 
Yeah, I think the obvious thing to check is if that lower hose is warm or hot while it's running. I doubt it's frozen but if you don't have enough antiFREEZE in the mix, it will. It's probably just the spring you're feeling but I'd see if it gets warm while the engine is on. It should.
 
'92's use a heat sensor on the thermo neck, it needs to be plugged in, as does the fan itself. If the junkyard rad had the heat sensor in it for the fan, it's a '91 or older and will not work.

Older heat sensors are Off/On and control a relay on the radiator support, newer use variable voltage to the computer, which controls the fan. The systems can't interchange parts.

Of course, if it's frozen, you don't have enough antifreeze. Since you just replaced it, what mix did you fill it with?
 
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