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Overheating, fan clutch?

bigalpha

bigalpha

Moderator
Location
Tucson, AZ
So, I did some searching and read some conflicting info about testing the fan clutch.

Some people say the fan should not move when the engine is cool. Some people say the fan should spin freely.

Which is it?

The Jeep is running super hot, so I'm trying to narrow down the culprit.
 
After the Jeep gets hot shut it off, open hood. If you can freely turn the fan with little to no effort, or it still free spins when hot like mine does it is bad. I just had the same issue. I got the new fan clutch but now I gotta find time to put it on.
 
cool engine=free spinning fan
hot engine=great resistance or non moving fan

*when motor is off of course
 
they don't contradict? they just worded it differently.if it spins freely when hot its bad.


make sure you have a fan shroud in good shape too.
 
Any driving. Even idling in the driveway causes it run blazing hot. It gets so hot, that I have to wear gloves just to open the hood because everything under there is on fire (not literally, of course).

Last night, the engine bay was still really hot like 4 hrs after I got home.

The only thing that really helps it cool down is if I run the heat in the Jeep for a few minutes. The electric fan runs when it should.
Is there a way to test the water pump or thermo w/o taking them out?
 
With the engine just turned off and blazing hot like the surface of the sun, the fan spins freely.

@magimerlin:
Where did you get your fan clutch from? From what I understand, replacing it is relatively easy.
 
I just replaced mine two nights ago, easy peezy if the shroud isn't in the way :)

She runs much cooler in the city now, unfortunately the fan is on pretty much all the time pulling my temps down from 100 (210 for ya yanks :p), on the highway she runs great though :cool:
 
Where did you buy yours from? So the new fan makes your engine run cooler than 210?

That's good to a certain point, isn't it? At what point is it too cool?
 
I just went through this scenario. Drove two hours to go off-roading and made it about eight feet before I noticed that the temp was about 230. Even with the electric fan running (I have a switch to force it on). Looking under the hood, it looked like the main fan was not spinning fast enough.
So I gave up and drove home. Had the heater on full to cool it. Once I was at highway speed, it came down to about 215, but went up again when I hit city streets.
It has a new radiator and water pump (about 1 yr old), same for t-stat.
Bought a new heavy duty fan clutch at Auto Zone for $36. The heavy duty cost the same as a standard. Started it up, and it went to 210 and you could see the t-stat kick in. Never went above 210 sitting in the driveway. I even put on the A/C to do a recharge and it never went above 210 during the 20 minutes.
 
no, the clutch fan is the engine belt driven one. the clutch is thermally controlled, the guts heat up, engage clutch and it spins at engine rpms to cool things down.
the aux fan is electric, comes on with a/c engaged or if really high temps are noticed.
 
So, I changed the fan clutch -- it was really easy. The jeep runs MUCH cooler now.

I can finally open the hood without needing to wear gloves and without burning myself to death. The Jeep still runs hot when I get her up to speed (60-70mph). At those speeds, the temp starts to rise.

What does that usually point to? Thermostat or water pump?
 
bigalpha said:
So, I changed the fan clutch -- it was really easy. The jeep runs MUCH cooler now.

I can finally open the hood without needing to wear gloves and without burning myself to death. The Jeep still runs hot when I get her up to speed (60-70mph). At those speeds, the temp starts to rise.

What does that usually point to? Thermostat or water pump?
Click to expand...

That's great news. I'm doing mine tomorrow.

Overheating at higher speeds (hi-way) usually indicates a low coolant flow. Could be radiator, gunk in block, water pump or any/all of these. Check the condition of coolant. Idle it up to temp with the cap off and see if your system is circulating.
 
One of the websites (4x4explorers) has a write-up on changing the fan clutch in a Wrangler (I think). One of the big things is getting a fan wrench.

My 1995 Sport didn't require a fan wrench. There were two small bolts that held the fan shroud (that came completely out); 4 bolts holding the fan+clutch to the pulley; 4 bolts holding the fan to the clutch.

The hardest part was getting my hand in between the fan blades and the engine and tightening/loosening the bolts.

Otherwise, it was pretty easy. You'll notice a huge difference in the way it sounds immediately. Before the replacement, the fan barely pulled any air through. After replacement, the fan was pulling mad air.

As far as the coolant, I took off the rad cap and ran the Jeep, and the Coolant actually dribbled out of the top of the radiator. When I hit the throttle, the coolant lowers, but it still dribbles out of the top at normal idle.

Plugged radiator maybe?
 
Cooling systems are under pressure, so I wouldn't be surprised a little was dribbling. if you let it get hot, it will do more than dribble. No one realizes how important the fan clutch is until they put a new one on.
 
Yeah, the fan clutch was a huge turning point on my road to recovery.

Is there a way to test the water pump? What about testing the flow of the radiator?

When I replaced the coolant, the freshwater from the hose seemed to flow through the radiator pretty easily.
 
If you are still battling the temp guage, and the e fan is working properly, you the next easiest thing is the temp switch. it could be sending a higher reading to the guage than reality. if you do anything else you might as well do the tstat and pump together. there is no way to test the flow really. but you have eliminated all problem areas at that point, so you'd be done anyway, other than a flush.
 
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