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Engine running hot in cold weather, not over heating

WalmartGardner

NAXJA Forum User
Location
NC
Hey guys,

I have been a fan of the NAXJA forums for years. Thank you so much for the information over the years. I have just registered my first account because I haven't been able to figure this out myself and would really appreciate some help.

I have found some similar threads to the title of this one, but never found a resolution in them - or the threads died.

My 97 XJ sport (bought January 2019, 95k miles) is getting warm even though the ambient temperature is fairly cool here in NC.

When warming it up in the morning, no matter how long I leave it, the temp gauge never surpasses 210F. When driving, it's a slightly (width of the temp needle) below 210F. But when I'm sat at a traffic light, or in a parking lot, after 3 to 5 minutes, the temperature reported raises to halfway to the next temperature tick above 210 (220?). At this point, the electric fans turns on, and lowers the temperature to 210, and then the electric fan turns off. Then the behaviour repeats. The temperature then raises halfway to the next tick again, electric fan on, temp lowers, electric fan off.

So far I have replaced the thermostat and the thermocouple.
I can't spin the mechanical fan all the way around - it goes maybe an 8th of a rotation. So I figure the fan clutch is working.

I'm at a loss because it only happens after driving it, and not when warning it up from cold.

I would love some input from you guys.

Thank you!
 
As an added note, this started happening roughly one week ago. Previously it would not get above 210 in temperature, even in the 100F weather we get in NC. I am concerned because this is happening in winter.
 
an xj will warm up to 218, kicking the fans on, if it idles long enough. just several minutes is possible, even in cold weather. they are designed to run at 210 while driving in any temperature. the e fan helps idle without overheating. I have overhauled my entire cooling system replacing everything with stock components and using a mishimoto aluminum radiator. it functions just like your say yours does, and will get to 218 at extended idle. I think your vehicle is operating normally.
 
I disagree, this in not normal, you should be concerned. The e-fan is doing its job, but in cooler weather, the engine temps should not rise above 210*. Overheating at idle, or in your case an unusual temperature rise, very strongly suggests a faulty mechanical fan clutch.
 
maybe. op said car is not overheating. if the vehicle is sitting in the same place sucking in air from the hot engine bay, it's not going to stay at 210. I think maybe 3-5 minutes is a little short, so clutch could be a bit weak or there could be a small blockage somewhere. but I have flushed my xj, replaced radiator, water pump, hoses, it will tick up if it's sitting still for a while.
 
Another vote for a faulty fan clutch.
 
maybe. op said car is not overheating. if the vehicle is sitting in the same place sucking in air from the hot engine bay, it's not going to stay at 210. I think maybe 3-5 minutes is a little short, so clutch could be a bit weak or there could be a small blockage somewhere. but I have flushed my xj, replaced radiator, water pump, hoses, it will tick up if it's sitting still for a while.


I agree that it is picky to be concerned about it when it's not overheating, it's just that I haven't had this behaviour from this xj before. Even in the >100F weather we get in the summer time. This is my road queen, but I will be taking her to the 4x4 beaches over summer and want to make sure she's in tip top shape. Thank you for your input.


@Tim_MN, thank you. I'll do the fan clutch this week. Based on everything I've read, I thought it might be that, but the fact that it didn't spin freely changed my mind. Thank you!

I'll definitely post my results after replacing the fan clutch this week.
 
Update

Fan clutch did the trick! I replaced it with a CarQuest xj fan clutch rather than the ZJ clutch. Performance is good.
I have a feeling with it being CarQuest, it may need replacing again soon lol
 
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