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Swapped radiators, interesting...

rcmf5525

rcmf5525

NAXJA Member
NAXJA Member
Location
Mobile, AL
I have a '92 XJ and started to get a crack around the upper neck on the radiator. I have a '99 that I was parting out that had a good radiator. I swapped them. Now my temp stays around 210* and my aux fan stays on. It does not overheat, hell it never gets more than the needle away from 210*. Never was that stable before. Sit at idle for a while and it would heat up, start moving cool down to under 180. Now, when it heats up it stays there...
 
rcmf5525 said:
I have a '92 XJ and started to get a crack around the upper neck on the radiator. I have a '99 that I was parting out that had a good radiator. I swapped them. Now my temp stays around 210* and my aux fan stays on. It does not overheat, hell it never gets more than the needle away from 210*. Never was that stable before. Sit at idle for a while and it would heat up, start moving cool down to under 180. Now, when it heats up it stays there...
Click to expand...

so whats the problem?

no need for a 180 thermostat. i would only use a 180 thermostat if it were the very last thing that kept it from overheating after evrything else in the cooling system checked out ok.

if you change out the thermo, use a 195.

i found the single core stock rad in my 89 to be the source of my high temps. new 3-core rad took care of the high temps while idling or slow driving in hot traffic.
 
no problem, I was puzzled about the difference when the radiators are the same and nothing else had changed.
 
Your old one probably had a bunch of mud caked inside the fins, pretty common and you can't usually get it out very easily unless you pressure wash from both sides (at which point you've already got it out, so why not just replace it right!).
 
The fan stays on now because it stays above the required temperature to turn it off...
 
ok..I would agree with that...so do you agree it doesn't seem right?

My 2001 is all stock...my aux fan rarely kicks on. My Jeep runs steady right around 210*F at operating temp.. that is according to my autoxray scanner readout, not the guage on my instrument panel...it has run that way since I bought it new in 2001. My aux fan kicks on if coolant temp reaches approx 222* F and shuts off when coolant temp drops to approx 213*F.
Some dealerships have reprogrammed the PCM to have the aux fan come on sooner if the customer has complained about heat soak/vapor lock hard restarts.

In any case, if your aux fan has to stay running all the time to keep your coolant temp at the recommended operating temp, what is gonna help you out on a hot day stuck in heavy traffic and your coolant temp rises?

No need to reply, if you don't think it is something to be concerned with...
 
McQue said:
ok..I would agree with that...so do you agree it doesn't seem right?

My 2001 is all stock...my aux fan rarely kicks on. My Jeep runs steady right around 210*F at operating temp.. that is according to my autoxray scanner readout, not the guage on my instrument panel...it has run that way since I bought it new in 2001. My aux fan kicks on if coolant temp reaches approx 222* F and shuts off when coolant temp drops to approx 213*F.
Some dealerships have reprogrammed the PCM to have the aux fan come on sooner if the customer has complained about heat soak/vapor lock hard restarts.

In any case, if your aux fan has to stay running all the time to keep your coolant temp at the recommended operating temp, what is gonna help you out on a hot day stuck in heavy traffic and your coolant temp rises?

No need to reply, if you don't think it is something to be concerned with...
Click to expand...

Thats what I was thinking. What happens when it is in the upper 90s? I guess I will wait and see...



No, the fan is not stuck on. It doesnt come on until it gets around 210 on the guage.
 
I'm not positive but I think your Jeep has two coolant temp sensors...
1 for the guage
1 for engine control
either one could be misleading you...
the engine control sensor may have your fan coming on too soon if its bad, or it may be good and you are running hotter than you think, if the one for the guage is bad....
 
haha, what is the normal temp of a 4.0? I have been plagued in my last two XJ's. First one, the aux fan was on a toggle, and I ended up replacing my radiator...once I replaced it, I sold it. My 94' doesn't have an aux fan...yet. And I am running around 210 degrees myself. I am going to flush and fill this weekend, and hopefully install my fan when it gets here, so I am looking for insite on a target temp.
 
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