Questions about the fan clutch & overheating

Joseph

TJ Enthusiast
Joined
Aug 20, 2018
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392
Location
North Jersey
So the Jeep has been overheating at idle about 15-20 degrees I’d say. I’ve known about this for a few weeks now but my short commute doesn’t really require any stopping so i’ve ignored it.

Today it hit close to right between 210-260. Usually it smooths out once I start driving but it stayed hot for about a mile and a half home. I hopped out to see if the fan clutch would keep spinning after shutoff, but it didn’t and stopped pretty quick.
1. Is there a test I can do for this cold? Engine off at running temp it spins freely.
2. Should I just replace it anyway?

Getting cold here in Jersey and hate myself for not nipping it in the bud when it was warmer. But works smoothed out and I have some money saved to get these parts. I’d like to do a Mopar pump and thermostat. I did a Mopar radiator sometime this summer and tstat it’s been great until now. 142k miles on the Jeep what can I expect.
 
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There should always be a bit of resistance to spinning when it is cool and not spin like a pinwheel. Is that what it's doing now.
 
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There should always be a bit of resistance to spinning when it is cool and not spin like a pinwheel. Is that what it's doing now.
Spins no problem right now warm, I’m still waiting on it to cool down so I can try spinning it and double check coolant

Forgot to mention the heat comes and goes when I idle, I know the hvac resistor or whatever it is needs to be replaced because my first two fan speeds take about 15 mins to come on and a few of the vent control options do too.
 
If it is warmed up it should not spin freely.

When you spin it does it is it like a pinwheel ?

If it does spin like a pinwheel the fan clutch is done.
 
If the blower resistor is done it normally takes out every speed but high so you may be dealing with a different issue. I would suggest removing the center bezel and inspecting the rear of the HVAC panel for any issues.
 
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1. Is there a test I can do for this cold? Engine off at running temp it spins freely.
2. Should I just replace it anyway?
The fan should only spin freely when the engine is cold, the fan clutch should stiffen so it can turn the fan when the engine is hot. It sounds like your fan clutch is bad.
 
Yes to both of your questions. I have a Mopar pump, Stant t stat, and a Hayden fan clutch in my Amazon cart right now. Unless someone has better brand recommendations (aside from the pump, Mopar).
2002 4.0 with AC, which belt should I purchase? Also, should I go ahead and replace the pulleys while I have it apart? Thanks again
 
This Gates belt cross references to the Mopar 4854033AB p/n which is what the Mopar Parts Guide shows as correct for the 2002 Wrangler 4.0L with A/C. https://www.amazon.com/dp/B000C2YCJG/?tag=wranglerorg-20

This Mopar definitely fits, it matches what the Mopar parts guide shows for your Jeep.
https://www.amazon.com/dp/B0049EFQ3O/?tag=wranglerorg-20

I'd consider replacing the idler pulley too. Rockauto has a bunch to choose from for your Jeep... https://www.rockauto.com/en/catalog/jeep,2002,wrangler,4.0l+l6,1386873,belt+drive,idler+pulley,6956
 
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I've never seen a viscous fan clutch spin freely when cold. The one I replaced a while back certainly didn't, but it was the cause of an overheating problem during idle. None of the tests I have read about would have shown the the clutch was bad. And the new one felt the same, except I could hear it engage when the engine warmed up.
 
This statement makes me think you have a low coolant level.
I topped off the coolant and it’s back to doing the normal overheat 10-20 degrees over at idle. That’s ok for now. I got a new fan clutch and thermostat coming in tomorrow, belt and Mopar pump won’t be here till the 24th.. But at least I can get to and from work. I started the jeep this morning and let it run for no more than a minute, went to pop the cap off and top off... Coolant everywhere
Had my boss come pick me up but I didn’t even get to the end of my road before it was creeping up to 260... must’ve hit about 240-245. Shut her down. Took almost a gallon of coolant after what I lost..

Anywho, filled her up, she’s driving quite normal now aside from the temp running over 10-20 degrees. Driving i’m actually getting cooler temps now.
 
I may have missed it, but do you know how old your current water pump is and what brand?

This is just a guess, but I’ve heard of some water pumps with the metal vanes getting so corroded that the vanes are nearly non existent, resulting in next to no flow of coolant. I’ve had those types of pumps on many vehicles but have never experienced that personally. All of mine had vanes still in great shape but started leaking from the weep holes when I had to change them.

Even if it’s a MOPAR pump currently on there its possible the plastic type vanes used on some could have broke.

You should be able to tell when you remove the pump.

Good luck, I know it’s frustrating.
 
I may have missed it, but do you know how old your current water pump is and what brand?

This is just a guess, but I’ve heard of some water pumps with the metal vanes getting so corroded that the vanes are nearly non existent, resulting in next to no flow of coolant. I’ve had those types of pumps on many vehicles but have never experienced that personally. All of mine had vanes still in great shape but started leaking from the weep holes when I had to change them.

Even if it’s a MOPAR pump currently on there its possible the plastic type vanes used on some could have broke.

You should be able to tell when you remove the pump.

Good luck, I know it’s frustrating.
It looks like the original pump to me. I got it at 125k and whoever owned it did most of the service at the dealer (according to carfax). The mopar pump is on its way at least and I can overhaul this before I have to go through this overheating bs again. 142k miles on it now
 
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