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10/20/2017 1:01:18 AM
9/22/2017 12:11:25 AM
Posted: 9/25/2005 8:19:59 PM EDT
Link Posted: 9/25/2005 8:24:15 PM EDT
[Last Edit: 9/26/2005 6:50:49 AM EDT by out-a-ammo]
Is your fan working, or missing the shroud?

Link Posted: 9/25/2005 8:24:32 PM EDT
[Last Edit: 9/25/2005 8:25:54 PM EDT by Skibane]
My guess would be a bad fan clutch.

When you're moving, the vehicle motion forces enough air through the radiator to keep things reasonably cool. However, when you're stationary, the fan is the only thing that moves air through the radiator. As a fan clutch ages, it starts to slip more and more, which makes the fan spin slower and slower with respect to the speed of the engine. Eventually, it just doesn't spin fast enough to keep the engine from running hot.
Link Posted: 9/25/2005 8:27:32 PM EDT
[Last Edit: 9/25/2005 8:28:08 PM EDT by Zardoz]
Could be the thermostat, water pump (listen for any strange noises coming from it, and look for water leaking out of it behind the pulley), temperature sensor, cracked fan blade(s), etc.

Take the radiator cap off and start the engine. Once the engine warms up, you should see the water circulate when the thermostat opens; you should also be able to feel it through the top radiator hose. If it doesn't, the thermostat's a good bet.
Link Posted: 9/25/2005 8:28:38 PM EDT
Check the fan and the thermostat.
Link Posted: 9/25/2005 8:35:28 PM EDT
[Last Edit: 9/25/2005 8:38:35 PM EDT by blackta6]
As stated previously watch for circulation in the radiator. My 1994 Ford F-150 has the plastic end caps on the radiator, as do most autos now, but in the winter it gets cold enough that the seals leak small amounts of fluid. Check out your radiator also, is what I am saying. Thanks for reminding me I need to fix my truck!

ETA: Just thinking about it, do you have an aux. fan for the A/C? If you do, it would be mounted direct to the radiator, the electric type. Make sure it runs when the A/C is turned on.
Link Posted: 9/25/2005 8:39:48 PM EDT
[Last Edit: 9/25/2005 8:46:33 PM EDT by red-don]
On my 96 Cherokee I drove it all day in 95° temps with no problem then it spewed all over when I shut it down. Replaced the radiator cap and no problems since. That is a cheap first try.

Fan clutch is easy to check, when the engine is hot shut it off and give the blades a spin. Thye should be stiff when hot and stop right away. Other than thay it may be the water pump. I have heared of erroded vanes, so it is not moving enough at low rpms. On the road the airflow is enough to compensate.
Link Posted: 9/25/2005 8:42:31 PM EDT
You need to check the electric fan relays,there should be three on the passenger side of the engine compartment.If the relays are working,you may have a bad electric fan.This fan is what should come on when in park,or at idle.If your fan clutch was defective on the primary fan,it would sound like an airplane motor,due to the fan turning the same revolutions as the motor.the clutch makes it run at lower revolutions.Last but not least,check the radiator size,it could be the wrong one,i know it is possible because i had a 1990,that somehow left the factory with a light duty radiator when it should have had the heavy duty model since it had AC.
Link Posted: 9/25/2005 8:46:00 PM EDT
Link Posted: 9/25/2005 8:51:34 PM EDT

Originally Posted By Skibane:
My guess would be a bad fan clutch.

When you're moving, the vehicle motion forces enough air through the radiator to keep things reasonably cool. However, when you're stationary, the fan is the only thing that moves air through the radiator. As a fan clutch ages, it starts to slip more and more, which makes the fan spin slower and slower with respect to the speed of the engine. Eventually, it just doesn't spin fast enough to keep the engine from running hot.




I tend to agree with Skibane. It can never hurt to swap out the thermostat and radiator cap (both are cheap enough), but the fact that you run cool at speed, but not when sitting idle, tells me you're not getting enough air flow through the radiator.

Open the hood:

1. Does the fan turn while the car is stationary?
2. Does the fan have a shroud?
3. Will a piece of paper get sucked to the front of the radiator while the fan is moving (i.e., is there enough air flow)?


While you're at it, probably a good idea to change the coolant and backflush the system.

The spot of water under the jeep is almost certainly humidity/condensation from running the AC.

Good luck!
Link Posted: 9/25/2005 9:01:16 PM EDT
tag
Link Posted: 9/25/2005 9:18:51 PM EDT

Originally Posted By Apatriot:
If your fan clutch was defective on the primary fan,it would sound like an airplane motor,due to the fan turning the same revolutions as the motor.the clutch makes it run at lower revolutions.



Usually, when a fan clutch goes bad, it starts slipping more than normal - it doesn't lock up and start spinning the same speed as the engine.

Most clutches have a thick silicone oil inside that serves as a hydraulic coupling between the engine and the fan blades (similar to the torque converter on an automatic transmission). As the clutch gets older, some of this oil starts to dissipate or leak through the seals around the clutch shaft. Less remaining oil means less coupling, which means more slippage, which means lower fan speed. Since the fan isn't as tightly coupled any more, it can now be easily spun by hand when the engine is hot, and will contine to rotate for up to several seconds afterwards. A good clutch will be difficult to spin by hand, and will stop rotating immediately afterwards.
Link Posted: 9/25/2005 9:58:31 PM EDT
Link Posted: 9/25/2005 10:11:57 PM EDT
[Last Edit: 9/25/2005 10:13:43 PM EDT by 22bad]
Electric fans don't have a fan clutch

eta: so you can sit in the same place, but in drive with the brake on and it does not overheat?
Link Posted: 9/25/2005 10:16:17 PM EDT
The smaller fan uses an electric motor to spin it (doesn't have a fan clutch), so it will always spin freely.

The larger, center-mounted fan uses the engine to spin it, via pulleys and a rubber drive belt. It shouldn't spin freely after the engine is hot, unless the fan clutch is defective.

The fan clutch looks like a circular piece of aluminum that is bolted to the center of the big fan. It has cooling fins cast into its exterior. A good-quality replacement shouldn't cost more than several hundred dollars from the "stealer" (or around $100 from an auto parts store), plus maybe $75 in labor to install it.

If the dealer refuses to cover the repair costs (or denies that there's any problem), I'd suggest taking the vehicle to an independent repair shop instead. Fixing it is probably not going to cost you enough to be worth the hassle of fighting with the dealer.
Link Posted: 9/25/2005 10:32:49 PM EDT

Originally Posted By Skibane:
The larger, center-mounted fan uses the engine to spin it, via pulleys and a rubber drive belt. It shouldn't spin freely after the engine is hot, unless the fan clutch is defective.



Yup, if it does have a fan clutch, that is where I would start looking
SOMETIMES you can tell that they are bad just by grabbing the blades and shaking the fan
it should have SOME play, but it should not be completely gone........its difficult to explain\describe
Link Posted: 9/25/2005 10:33:14 PM EDT
Link Posted: 9/25/2005 10:44:39 PM EDT
YOU NEED A COOLING FAN RELAY

Way common failure on 97 up Grand Cherokees !!
I have done at least a dozen of them so far this
summer .

It not under the hood in the relay box , and it's not on
fan shroud . It's buried on the front of the right inner
fender well . If your real good and you have the right
tools you can get to it by pulling the right head light
assembly and working through a tiny 2" hole .

Otherwise you have to pull the bumper grill fascia , both
headlights and the support structure to access the relay .

Link Posted: 9/27/2005 8:54:57 PM EDT
Link Posted: 9/27/2005 10:50:38 PM EDT

Originally Posted By thedukeryan:
I guess chrome should know after installing over a dozen of them



Its always good to ask someone experienced with your particular problem, but the rest of us are still here the rest of the time
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