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Mechanical Help

zachndorsett

NAXJA Forum User
Location
Tennessee
Having problems with my radiator. Heats up when stopped. Whether i have been driving for a while and stop at a red light or start it up and sit there. The thermostat rises above normal and i cant figure out why.
 
if it usually happens during a stop, I'd suspect a fan clutch is on its way out. How many miles are on your xj and is it the original fan clutch? I'm not saying it can't be anything else but usually a worn out fan clutch allows temps to rise while idling or at a light ect. Your rad is probably fine but I would flush the system with one of those T kits and a garden hose and replace with fresh coolant and a new thermostat if yours is old.
 
I have flushed it out twice and put 2 different brand of coolants in it. Thats not the problem. I got 135,000 miles on it and it is the original fan clutch. It doesnt heat up to the red but it goes over normal. Then the fan kicks in but it doesnt go down, it just keeps it from rising anymore.
 
If it is the original fan clutch it is probably toast, and is mostly freewheeling on the shaft and not pulling air with any power. If that's the case, then you are getting very little airflow at idle. When you're in motion there is airflow, and you have no problem maintaining you temperature - that indicates the your radiator, water pump, thermostat, etc. are functioning well enough.

The usual test for a fan clutch is to start with a dead-cold engine, and give the mechanical fan a spin with your hand, noting the resistance you feel. Then run the motor until it is good and warm (190 degrees or above), shut it down and immediately pop the hood and spin the fan again. When hot it should have significantly more resistance than when cold, since the thermally actuated viscous coupling is supposed to "grab" the fan shaft harder when warm. If there is little or no difference in spin resistance between hot and cold, that indicates a worn out fan clutch.

In my opinion, the test is hard to use conclusively without having experience with how viscous fan clutches should feel. But it is usually advisable to replace it anyways with the symptoms you describe. It is not an expensive part (less than $50), but it is a slight PITA to R&R due to the lack of space between radiator and fan, and the fact that the one-peice fan shroud cannot be removed entirely from the car until the fan (or radiator) is removed, which makes removing the fan mounting bolts annoying.

Also, many people upgrade to a ZJ ('93-'98 Grand Cherokee) Heavy Duty Fan Clutch, which has a more agressive viscous coupling. It will spin the fan faster than a normal clutch, which increases airflow but robs some power and fuel milage (at low speeds at least). It's a good idea if you do a lot of hot-weather slow speed driving.
 
Thats exactly how my fan is running. Works great when driving because air can feed through but when stopped it rises. I have felt the fan after it sat over night, not much to none resistance than started it up and drove it around then stopped and felt it again. Same effects, not much to none resistance. So fan clutch is what i have been told by my cousin who is a jeep fanatic but i wanted to get multiple opinions to make sure. So since that is the case what are alternatives to replacing the fan clutch other than the heavy duty one? That one sounds like something i might need and will look at but what other options do i have? Also where do i look to find these?
 
Auto parts stores dont always sell the best quality. Or every product. I would rather by a product that is stronger and will last longer and made for offroad then buy something that is stock or cheap just to fix it and get it replaced.
 
Around here, a fan clutch is a fan clutch. Your over thinking it. Its just a fan clutch, not a set of tires. Buy a ZJ one like stated above. You'll easly get 70k miles out of the cheapest one you buy. They dont cost much and they're easy to replace.
 
Go to napa and get a grand cherokee fan clutch. Use your search function at the top of your screen and you will be able to find the part number.
 
Get the Napa ZJ fan clutch, and snap the little knives off the front,

Dont get the heavy duty ZJ clutch, as it is supposedly too big
 
174967.jpg

Napa #TEM272310 $42.99

Here are some discussion which may help you,
http://www.naxja.org/forum/showthread.php?t=1002297
http://www.naxja.org/forum/showthread.php?t=993344

GL
 
Any fixed fan will eat gas. Replace the clutch if it's bad. When warmed up - it should be stiff and not freewheel.

Another cause is the e-fan not kicking on, the 87-90 thermal sensor is in the radiator, which is way to late in the cooling cycle to kick on. If it has air, kick that on - the a/c clutch circuit is also a fan relay switch, of course the e-fan should turn on using air.

The relay itself could also be bad, don't forget to check the e-fan, too.

87-90 fan thermal switches are exactly that - off/on, 91 up are variable voltage inputs to the computer, and that kicks the relay in, they can't work direct to a relay. Short version, that's how I found out.

The best bypass control I've found to kick the e-fan is from Speedway, hooks up to the gauge out put and can dial adjust when it kicks in.

Some just take off and convert to all electric, you need 2400 CFM to do it, and Taurus fans are too much load on the alternator without more mods. Best thing to do is just replace the friggin clutch and be done with it.

Caution: the three core replacement radiators are really too much, I've suffered low temps since I installed the first and replaced the clutch, it takes a 90 degree day idling in the drive thru to even get to 210. A two core would have done it all, and the conversion to an open cooling system is a lot of cost for little return. Turtle tanks are a commodity item on the shelf at my store.

Yeah, there's some threads on it.
 
John was kidding i think....

A flex fan will cause more noise, cool less, and use more fuel. It will also cut your hand off if you carelessly get too near the fan.
 
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