New HEAVY DUTY fan clutch?

I got into a crash about 2 years back in my 2000 4.7L dodge Dakota and it Somehow messed up my fan clutch (which actually worked perfectly fine for about another 2 months). I had to replace the oem clutch with another just like my mechanic said to! And it worked for the most part. it started engaging waaay more often than it usually had been cold or hot. But I just decided to live with it until a few months ago when I had to make a long distance trip from Knoxville to Nashville, I decided to go have everything fixed such as AC and powered steering and antifreeze lines by my mechanic including another new clutch! And all the noises went away! I could hear the rumble of my flowmaster super 10 and it sounded mean and clean!! I made it to Nashville the next day without any problem at all!! A few weeks go by and I start my truck up and I swear to god that noise came back sometimes I can go on short drives and it on the return trip it will turn on and sometimes I’ll be cruising down the interstate and it suddenly comes on and stays on the rest of the way! it varies but it just Keeps coming on when it’s definitely not supposed to and what I want to know is if I need the heavy duty oem clutch or if there is something else wrong? Sorry for the long post but I just really need some help!! Also if anyone can recommend an good body shop in Norfolk VA, it would be greatly appreciated!!!

Just for clarification, are you talking about the old style mechanical fan that uses a liquid inside to engage the fan and otherwise free wheels, or an electric fan that turns on with a relay? Or something else entirely? On the old clutches, when they would get bad they would roar and would be on all the time.

It’s the old one because when it starts making noises it roars really loudly but it doesn’t seem to free wheel, it’s pretty sturdy and stiff when the truck is not running

If it doesn’t free wheel and is roars, it needs to be replaced. I’d just get one at NAPA or someplace.

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Is there any way to prevent this from happening? This is the 3rd clutch in 2 years and the most recent one was about 3 months ago

Have you talked to the mechanic who put it in? Most Parts have a guarantee and most mechanics near me guarantee their work for a year.

I looked on Rock Auto which has a selection of 6 fan clutches for this truck and 5 of them are called heavy duty. They range from $22 To $37. Even the $22 one is listed as heavy duty.

Not yet No because as of right now I’m in Virginia and my truck is in Nashville with my mother, plus wanted some other opinions before I did anything. What I really want to know however is if a heavy duty fan clutch would do better than a standard because as I said earlier this is the 3rd clutch in 2 years and it’s becoming quite annoying. Maybe one from summit racing or something like that? The reason I’m asking is because I have to drive that truck back and forth between Norfolk and Knoxville and I could really use the gas mileage and horse power and obviously if there is something causing this I would love to know so I may prevent it because I’m at a loss

I never replace the clutch type fans when they fail. I replace them with a flex fan. Far cheaper and they work better too.

What does “heavy duty” mean. I have installed non thermal ‘centrifugal’ fan clutches on vehicles that were driven in heavy traffic and required long periods of idling and they were labelled ‘heavy duty.’ Those clutches are engaged even at cool temperatures and released as RPMs increased. Possibly the OP’s Dakota has such a clutch installed.

4.7 L Dodge Dakota and gas mileage don’t really go in the same sentence .


Okay so my fan and the fan clutch is driven by the belt that turns the water pump obviously. and from what I understand is that a heavy duty clutch has deeper ridges so to speak for better heat dissipation than a normal fan clutch does if that makes any sense

But my mechanic installed a normal stock fan clutch a few months ago Which did great for a few weeks but it seems to have locked up and makes noise at random times and continues to do so until the truck sits for a little while and or it just decides to stop while I drive (however sometimes it does it as soon as I start the truck and does whatever it wants apparently), and traffic in the part of Nashville I’m talking about is light not too heavy.

Regardless how new your fan clutch is it seems to be failing and if so that means it needs to be replaced with a more reliable model.

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Whenever my fan clutches have failed, they fail in the off position. They don’t kick in when the truck is getting hot. To say they are failing when they come on “too much” has never been my experience and makes no sense to me. I’m driving one ton dualies towing 8,000 to 10,000 lbs in the mountains. I find it quite reassuring to hear the fan kick on, it’s doing what it’s supposed to. I think you are mistaken that it is failing, it’s working. And they do come on when you first start the vehicle. That’s the way they work. Mine stay on for about a minute before they settle down, then only come back on when they think the engine is hot enough. Maybe you don’t think the engine needs to be cooled, but that bimetallic coil certainly does. You’re only running a heavy duty clutch, I use severe duty. No way I want my truck to overheat.

What matters is the temperature of the bimetallic spring. As long as the hub is cooled off, it should turn by hand with relative ease. You can try this with the new one at the parts store.

The difference between standard, heavy duty and severe duty is how much they engage or lock up. The standard unit will lock up around 70%. In other words, the driven side will be turning 100% pulley speed and when engaged, the fan side will be 70% of that. They go up in percentage with the severe duty being around 90% engaged.

I’ve replaced a number of these and had them fail in both ways; freewheeling and not engaging and then ones that roared like crazy because they were locked up all the time. Depends on the failure mechanism.

When they fail engaged, I get your issue- it sucks power like crazy on the highway and mileage suffers. I tried flex fans with reasonable success but it’s a trade off. It’s like middle ground. I would prefer the clutch fan works as designed.

I think you need to look at how they are failing to help understand why. But spending a bit more money for the best one you can afford would be my first suggestion.

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I have had only a few vehicles with fan clutches, never noticed loud noise or loss of power when engaged. The only thing I ever noticed was when a clutch failed, the fan would continue to turn for a few seconds after I turned off the engine, then it made a squeaking noise.

That’s because when they function correctly, the viscous clutch slips at higher rpms so no roaring. When they fail engaged, you know it. Very loud roaring and the load on the engine is significant.

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So the original fan/fan-clutch worked ok. then you got in an accident, and 2 months later the fan-clutch failed, which you think was caused by the accident. Replacing just the fan-clutch only works for a while, and doesn’t seem to be solving the problem. Is that right? Two ideas

  • The fan itself was also damaged in the accident.
  • The replacement fan-clutches have all been faulty from the get-go. Try buying an oem version from a dealership.

To add to what twin turbo said, you’ll generally notice more fan noise with the “heavy duty” fan clutch, as it is engaged more.

And to add to what George said, the oem (the exact part that originally came on the truck) fan clutch should function as you’re expecting it to. You might check on Rockauto and see if they list an “oem” version.

The aftermarket versions look to be priced in the $25-$35 range, while the mopar oem version is priced around $130.

Ahh. That stinks! I might just deal with the fan roaring for the additional $100.