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Clutch Fan

3K views 17 replies 8 participants last post by  JE13BigHorn 
#1 ·
I've done some searching and can't really get a definitive answer to my question. My Ram has 3500 miles on it... Hemi motor... my clutch fan is extremely loud at times. There doesn't seem to be any rhyme or reason for when it happens. It has happened in the morning when first cranking up. It has also happened after driving 5 miles then going through a drive thru and when I leave the drive thru it gets really loud for a half mile or so. It also happens at times in the afternoon when I leave work. At that time it's 90 degrees and it stays loud for the same amount of time as it does in the mornings after setting all night. I'm wondering if the clutch fan may be bad or if this is normal on the '13's?
 
#7 ·
Sean, That was my initial thought. However, it does it with the air on or off. That's another thing I've tried eliminating. The a/c doesn't seem to have any affect. This is a loud sound that conintuously goes up with the RPM's of the motor. It is loud and seems to rob a little acceleration.
 
#9 · (Edited)
To answer your question about fan clutches JE13BigHorn; Many different type of clutches to fans depending on the vehicle requirements; A Standard, Heavy Duty, and a Severe Duty. But as far as typical operation, fan clutches are either Thermal or Non-Thermal(also known as Centrifigal). Our Ram uses the Thermal, which when starting cold, the fluid inside the clutch has settled in the working area from sitting overnight. This is what engages the clutch fan at first startup but disengages shortly after. The air temp coming through the radiator is sensed by the thermal spring on the front of the thermal fan clutch. It expands and contracts with the change in air temp operating a valve inside the clutch. When cold, the silicone drive fluid is pumped from the working area to the reservoir. When hot, the valve opens allowing fluid from the reservoir to be transferred to the working area thereby increasing the fan speed. The clutch disengages as the air temp decreases, closing the valve and allowing the silicone fluid to be pumped back into the reservoir. SOOOO, long story short, a thermal fan clutch is engaged on a cold start up because the fluid has drained into the working area when the engine is shut off. The fan clutch will slow down shortly after startup as a result of a pumping action produced by a difference in speed between the shaft and the body of the clutch.:smileup:
 
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#10 ·
Gantman, That makes sense. So would you be concerned that it does it even after operating for a while. There are times when I drive a few miles, whether it be through mcdonalds or just stopping at a red light, that when I accelerate again the fan is loud for a few thousand feet up to a mile from beginning acceleration. That is what bothered me... That and the fact that the fan is extremely loud. I'm probably going to take it in to the dealer to have it checked, but I didn't want to end up in there and having not done any research to help explain my situation. I appreciate your explanation. It does definitley make sense.
 
#12 ·
Yes I would still bring it in to have your service department test drive it to try and duplicate your findings. Not every brand new part is always perfect. You may just have a defective fan clutch that had problems during manufacturing. For example, faulty thermal spring or silicone drive fluid. I remember replacing my fan clutch on my ole 96 Dakota with a 5.9Magnum and I decided to install an aftermarket HD fan clutch to replace my bad OE standard and yes you guessed it, much much louder when engaged. Hey good luck with your Service visit and keep us up on their findings with your truck.:smileup:
 
#11 ·
There are times when I drive a few miles, whether it be through mcdonalds or just stopping at a red light, that when I accelerate again the fan is loud for a few thousand feet up to a mile from beginning acceleration.
Likely it is just that when sitting idle in the drive through the temperature gets hot enough for the thermostatic spring on the clutch fan to allow the fan to engage. Then once driving down the road you have airflow through the radiator, engine bay, etc. and the temp cools down a little and the clutch fan disengages again.
 
#14 · (Edited)
I'm thinking the loudness you're hearing is the fan pulling more air as it gets more torque from the clutch engaging. Once the temp goes down, and the fluid drains, slowly disengaging the clutch, the fan looses torque and doesn't pull as much air so it quiets down.
 
#15 ·
My wife and I noticed the same thing twice at weird times when leaving from a stop. We both looked at each other and thought it was the tranny then like you say soon after it goes away. That's when I wrote it off as the clutch fan. It was just kinda loud. Louder than it seems that it should be and the fact it only happened twice in 2000 miles too. I'm in Cali and its been 100+ almost the whole time I've owned it.
Cheers!
 
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