Bad fan clutch? - JeepForum.com
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post #1 of 25 Old 08-21-2017, 08:05 PM Thread Starter
Gordknight412
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Bad fan clutch?

So I've noticed that my radiator fan is EXTREMELY loud while accelerating in gears 1-3. No noise at all in 4th and 5th. Granted I had the AC on and its above 90 here right now. It always does it in the morning after sitting overnight but it seems to be doing it more often now. I did some research and I am seeing conflicting opinions on how much the fan should spin on a cold engine by hand. After parking my Jeep for two or three hours I went back out and lifted the hood. Spun the fan by hand and it has a lot of resistance. Moves maybe an inch or two from a quick push by hand.

The jeep has 137k miles and I am guessing it is the original stock fan clutch. No way to know for sure because I dont have the original owners records.

Does this sound like a bad fan clutch?

Thanks!

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post #2 of 25 Old 08-21-2017, 08:59 PM
jkp
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Yep, it will lock up soon. Then your gas mileage and pwr will drop due to the extra drag.

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post #3 of 25 Old 08-21-2017, 09:03 PM Thread Starter
Gordknight412
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Quote:
Originally Posted by jkp View Post
Yep, it will lock up soon. Then your gas mileage and pwr will drop due to the extra drag.
I see thanks. Should I replace the thermostat while I'm at it?
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post #4 of 25 Old 08-21-2017, 09:07 PM
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If you don't know the history, it wouldn't be a bad idea. Also check the water pump bearing play and the weep hole.

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post #5 of 25 Old 08-21-2017, 09:31 PM Thread Starter
Gordknight412
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Would I be okay with a standard duty clutch fan as they are cheaper?
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post #6 of 25 Old 08-22-2017, 12:41 AM
TheBoogieman
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Quote:
Originally Posted by Gordknight412 View Post
So I've noticed that my radiator fan is EXTREMELY loud while accelerating in gears 1-3. No noise at all in 4th and 5th. Granted I had the AC on and its above 90 here right now. It always does it in the morning after sitting overnight but it seems to be doing it more often now. I did some research and I am seeing conflicting opinions on how much the fan should spin on a cold engine by hand. After parking my Jeep for two or three hours I went back out and lifted the hood. Spun the fan by hand and it has a lot of resistance. Moves maybe an inch or two from a quick push.
To test whether or not your fan clutch needs to be replaced, simply spin your Jeep's fan by hand while the engine is cold and if it spins freely 5 rotations or more, it will need to be replaced.

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Originally Posted by jeepinmichguy_ View Post
TheBoogieman is a jerk.
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post #7 of 25 Old 08-22-2017, 01:09 AM Thread Starter
Gordknight412
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Well when the engine is cold I can move the fan by hand but it only moves an inch then stops. When the engine is warm I can still move it by hand but the second I let go of the fan it stops. Cant push it and let go and have it still move even a centimeter. Isn't that bad? Shouldn't it at least go like a half of a single rotation?
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post #8 of 25 Old 08-22-2017, 04:19 AM
TheBoogieman
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Quote:
Originally Posted by Gordknight412 View Post
Well when the engine is cold I can move the fan by hand but it only moves an inch then stops. When the engine is warm I can still move it by hand but the second I let go of the fan it stops. Cant push it and let go and have it still move even a centimeter. Isn't that bad? Shouldn't it at least go like a half of a single rotation?

How To Tell If A Fan Clutch Is Defective
1) Check for oil streaks (or dust collected on oil streaks) on the fan clutch. It's a sure sign that the internal fluid that provides the clutch action is leaking.
2) Check for a worn bearing. Grasp the fan blade on either end, with the engine off, and check for lateral movement. If there's more than 1/4" of side-to-side movement, the bearing is worn and the unit needs replacement.
3) Check for proper fan clutch operation. First, run the engine until operating temperature is reached. Next, with the engine off, give the fan blade a gentle spin. If it rotates more than twice, the clutch is worn and needs replacing. If fan rotation is rough or noisy, or the fan fails to turn, the unit is worn out and needs replacement.

Courtesy of Flowkooler
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post #9 of 25 Old 08-22-2017, 06:14 AM
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Quote:
Originally Posted by Gordknight412 View Post
Would I be okay with a standard duty clutch fan as they are cheaper?
Standard duty is a good choice. The "heavy duty" fans tend to lock up earlier running the fan unnecessarily and lots of folks have complained they are loud.

Given the stiffness of the fan after warming up I'd say it's a good bet yours is no good. You don't have to open up the coolant system to swap the fan so if your thermostat is working I wouldn't bother to replace it. There really is no savings in labor or parts doing the two jobs at the same time.

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post #10 of 25 Old 08-22-2017, 06:47 AM
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Quote:
Originally Posted by Gordknight412 View Post
So I've noticed that my radiator fan is EXTREMELY loud while accelerating in gears 1-3. No noise at all in 4th and 5th. Granted I had the AC on and its above 90 here right now. It always does it in the morning after sitting overnight but it seems to be doing it more often now. I did some research and I am seeing conflicting opinions on how much the fan should spin on a cold engine by hand. After parking my Jeep for two or three hours I went back out and lifted the hood. Spun the fan by hand and it has a lot of resistance. Moves maybe an inch or two from a quick push by hand.

The jeep has 137k miles and I am guessing it is the original stock fan clutch. No way to know for sure because I dont have the original owners records.

Does this sound like a bad fan clutch?

Thanks!
To me, that sounds like a "heavy duty" or "severe duty" fan clutch that's operating as designed.

If you're testing "cold," you really need to run the engine for 30 seconds to a minute or so before checking (with the AC turned off, but with the thing on full heat, full fan in any position except defrost). When they sit, sometimes the fluid in them pools at the bottom of the fan clutch, and you get a blast of full engagement until they've spun up properly and centrifugal force distributes the fluid evenly around the fan clutch. Shut the engine off before it reaches thermostat temp. Then you should be set for a "cold" test, turning the thing with your hands.

A slightly more "dangerous" but also informative test is, after it's been running 30 to 60 seconds, take the cardboard tube from a paper towel roll, carefully touch it to the back of the fan blades and apply a bit of pressure. It should be disengaged enough at that point that you can stop the rotation with the cardboard tube. You will still feel it wanting to turn some, but the fan clutch should slip enough to be held stopped by a cardboard tube at idle RPM's with a cold radiator.

The subjective test for proper hot operation is a drive in a lower speed limit area (residential streets or a large parking lot). Sit stopped on a hot afternoon with the AC on (if it works). Watch your scan tool live data, set up a gauge or graph for Engine Coolant Temperature. With the engine coolant temp above 200℉, after sitting still for 30 seconds to a minute, you should hear the fan engage. Take off and run in 2nd or 3rd gear at about 25mph to 30mph. The fan should stay engaged (LOUD!) for anywhere from 15 seconds to maybe 60 seconds as the air flow increases and the air temp of the air coming out of the radiator drops. If it doesn't quiet down noticeably after 60 seconds (a half mile) at 30mph in 2nd or 3rd gear, the fan clutch is locked up.

If it doesn't sound like an airplane taking off when you pull off from a stop with the coolant temp above 200℉, the clutch probably isn't properly engaging. You can do the cardboard tube test with the engine hot. With the coolant temp over 200℉, sitting parked and idling, it should not be possible to stop the fan blades with a cardboard tube from a paper towel. If you press harder, it should just start shredding the tube. Most fan clutches that are over 10 years old or over 100,000 miles in service will fail to engage when hot, and the fan is doing nothing useful to cool the engine.

Properly working fan clutches, especially "heavy duty" or "severe duty" ones can be loud at times. They should quiet down when the air temp coming out of the radiator drops.

Oh, and check in front of the AC condenser and between the radiator and the AC condenser. If it's full of leaves or other debris, it won't be drawing cool air through the radiator, and that will keep the fan clutch engaged longer, as well as make your engine run hotter than it should.

I'm not arguing, I'm just explaining why my position is correct.
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post #11 of 25 Old 08-22-2017, 07:46 AM
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FYI, here's what the FSM says about testing the fan clutch:

VISCOUS FAN DRIVE

NOISE
NOTE: It is normal for fan noise to be louder (roaring)
when:
The under hood temperature is above the
engagement point for the viscous drive coupling. This
may occur when ambient (outside air temperature) is
very high.
Engine loads and temperatures are high such as
when towing a trailer.
Cool silicone fluid within the fan drive unit is
being redistributed back to its normal disengaged
(warm) position. This can occur during the first 15
seconds to one minute after engine start-up on a cold
engine.

LEAKS
Viscous fan drive operation is not affected by small
oil stains near the drive bearing. If leakage appears
excessive, replace the fan drive unit.

TESTING
If the fan assembly free-wheels without drag (the
fan blades will revolve more than five turns when
spun by hand), replace the fan drive. This spin test
must be performed when the engine is cool.
For the following test, the cooling system must be
in good condition. It also will ensure against excessively
high coolant temperature.
WARNING: BE SURE THAT THERE IS ADEQUATE
FAN BLADE CLEARANCE BEFORE DRILLING.
(1) Drill a 3.18 mm (1/8 in.) diameter hole in the
top center of the fan shroud.
(2) Obtain a dial thermometer with an 8 inch stem
(or equivalent). It should have a range of -18 - 105C
(-4- 220 F). Insert thermometer through the hole in
the shroud. Be sure that there is adequate clearance
from the fan blades.
(3) Connect a tachometer and an engine ignition
timing light (timing light is to be used as a strobe
light).
(4) Block the air flow through the radiator. Secure
a sheet of plastic in front of the radiator (or air conditioner
condenser). Use tape at the top to secure the
plastic and be sure that the air flow is blocked.
(5) Be sure that the air conditioner (if equipped) is
turned off.
WARNING: USE EXTREME CAUTION WHEN THE
ENGINE IS OPERATING. DO NOT STAND IN A
DIRECT LINE WITH THE FAN. DO NOT PUT YOUR
HANDS NEAR THE PULLEYS, BELTS OR FAN. DO
NOT WEAR LOOSE CLOTHING.
(6) Start the engine and operate at 2400 rpm.
Within ten minutes the air temperature (indicated on
the dial thermometer) should be up to 88 C (190 F).
Fan drive engagement should have started to occur
at between 74 - 85 C (165 - 185 F). Engagement
is distinguishable by a definite increase in fan flow
noise (roaring). The timing light also will indicate an
increase in the speed of the fan.
(7) When the air temperature reaches 88 C (190
F), remove the plastic sheet. Fan drive disengagement
should have started to occur at between 57 -
82 C (135 - 180 F). A definite decrease of fan flow
noise (roaring) should be noticed. If not, replace the
defective viscous fan drive unit.

CAUTION: Engines equipped with serpentine drive
belts have reverse rotating fans and viscous fan
drives. They are marked with the word REVERSE to
designate their usage. Installation of the wrong fan
or viscous fan drive can result in engine overheating.

CAUTION: If the viscous fan drive is replaced
because of mechanical damage, the cooling fan
blades should also be inspected. Inspect for fatigue
cracks, loose blades, or loose rivets that could
have resulted from excessive vibration. Replace fan
blade assembly if any of these conditions are
found. Also inspect water pump bearing and shaft
assembly for any related damage due to a viscous
fan drive malfunction.
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post #12 of 25 Old 08-22-2017, 07:47 AM
Shark_13
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Hmm interesting I have to do some of these tests. Lately I was thinking I've been hearing the fan more often/louder, mileage seems to have gone down a bit.
Hot or cold, it comes to a stop pretty quickly when I soon it by hand, like less than 1/4 turn....
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post #13 of 25 Old 08-22-2017, 07:48 AM
JEK3
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Quote:
Originally Posted by Shark_13 View Post
Hot or cold, it comes to a stop pretty quickly when I soon it by hand, like less than 1/4 turn....
That's what mine does.
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post #14 of 25 Old 08-22-2017, 08:19 AM
Racer-X
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Quote:
Originally Posted by JEK3 View Post
FYI, here's what the FSM says about testing the fan clutch:

VISCOUS FAN DRIVE

NOISE
NOTE: It is normal for fan noise to be louder (roaring)
when:
The under hood temperature is above the
engagement point for the viscous drive coupling. This
may occur when ambient (outside air temperature) is
very high.
Engine loads and temperatures are high such as
when towing a trailer.
Cool silicone fluid within the fan drive unit is
being redistributed back to its normal disengaged
(warm) position. This can occur during the first 15
seconds to one minute after engine start-up on a cold
engine.

LEAKS
Viscous fan drive operation is not affected by small
oil stains near the drive bearing. If leakage appears
excessive, replace the fan drive unit.

TESTING
If the fan assembly free-wheels without drag (the
fan blades will revolve more than five turns when
spun by hand), replace the fan drive. This spin test
must be performed when the engine is cool.
For the following test, the cooling system must be
in good condition. It also will ensure against excessively
high coolant temperature.
WARNING: BE SURE THAT THERE IS ADEQUATE
FAN BLADE CLEARANCE BEFORE DRILLING.
(1) Drill a 3.18 mm (1/8 in.) diameter hole in the
top center of the fan shroud.
(2) Obtain a dial thermometer with an 8 inch stem
(or equivalent). It should have a range of -18 - 105C
(-4- 220 F). Insert thermometer through the hole in
the shroud. Be sure that there is adequate clearance
from the fan blades.
(3) Connect a tachometer and an engine ignition
timing light (timing light is to be used as a strobe
light).
(4) Block the air flow through the radiator. Secure
a sheet of plastic in front of the radiator (or air conditioner
condenser). Use tape at the top to secure the
plastic and be sure that the air flow is blocked.
(5) Be sure that the air conditioner (if equipped) is
turned off.
WARNING: USE EXTREME CAUTION WHEN THE
ENGINE IS OPERATING. DO NOT STAND IN A
DIRECT LINE WITH THE FAN. DO NOT PUT YOUR
HANDS NEAR THE PULLEYS, BELTS OR FAN. DO
NOT WEAR LOOSE CLOTHING.
(6) Start the engine and operate at 2400 rpm.
Within ten minutes the air temperature (indicated on
the dial thermometer) should be up to 88 C (190 F).
Fan drive engagement should have started to occur
at between 74 - 85 C (165 - 185 F). Engagement
is distinguishable by a definite increase in fan flow
noise (roaring). The timing light also will indicate an
increase in the speed of the fan.
(7) When the air temperature reaches 88 C (190
F), remove the plastic sheet. Fan drive disengagement
should have started to occur at between 57 -
82 C (135 - 180 F). A definite decrease of fan flow
noise (roaring) should be noticed. If not, replace the
defective viscous fan drive unit.

CAUTION: Engines equipped with serpentine drive
belts have reverse rotating fans and viscous fan
drives. They are marked with the word REVERSE to
designate their usage. Installation of the wrong fan
or viscous fan drive can result in engine overheating.

CAUTION: If the viscous fan drive is replaced
because of mechanical damage, the cooling fan
blades should also be inspected. Inspect for fatigue
cracks, loose blades, or loose rivets that could
have resulted from excessive vibration. Replace fan
blade assembly if any of these conditions are
found. Also inspect water pump bearing and shaft
assembly for any related damage due to a viscous
fan drive malfunction.
A few notes about the test procedure here.
  1. Engine coolant temp is a fairly good proxy for the air temp as measured by a thermometer in the air space between the fan and the radiator. It's also less risky. You can certainly run the test once without the thermometer, using just ECT (from the live data shown on a scan tool) for your temps, and if the result looks like a failure, then drill the hole and put a long stem thermometer in the hole.
  2. You want to monitor engine coolant temp (either with the dash gauge or with a scan tool) so you don't overheat your engine with this test. Heed that caution at the beginning, "For the following test, the cooling system must be in good condition. It also will ensure against excessively high coolant temperature." You can overheat the engine with this test. IMO, that cautionary statement should be LOUDER and bolder.
  3. If you must drill the hole and put a long stem thermometer in there, drill about half way between the center and the side where the blades are going down, away from the thermometer. Be sure to secure the thermometer with wire and/or tape so it can't rock in the hole and the end can't make contact with the fan blades, even when the fan spins up and starts drawing a lot of air. If the thermometer stem gets sucked into the fan blades, it can damage any or all of these items: the shroud, the thermometer, the radiator and the fan blades. It can also send pieces of those items flying which could hurt if you get hit by the shrapnel. Don't ask me how I know this.
Quote:
Originally Posted by Shark_13 View Post
Hmm interesting I have to do some of these tests. Lately I was thinking I've been hearing the fan more often/louder, mileage seems to have gone down a bit.
Hot or cold, it comes to a stop pretty quickly when I soon it by hand, like less than 1/4 turn....
It could actually be locking up. That's a more rare form of failure, but it's certainly possible.

I'm not arguing, I'm just explaining why my position is correct.
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post #15 of 25 Old 08-22-2017, 08:51 AM Thread Starter
Gordknight412
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Thanks for the information everyone! Im not sure if my fan is HD or not. What got me thinking its bad is how little it turns by hand and the fact that even after the engine has been running for a good while and the engine temp is where its normally at (for my jeep is a hair over 210) the fan sounds like a jet engine every time I start in first again after a stop light until I hit 4 th gear.
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