03 Dak QC 4.7 545RFE - When I first start the truck up after it has been sitting for a while, and start driving, it makes a "roaring" sound, similar to a dump truck, or moving alot of air. It usually does this for a minute or two. I'm assuming this is the clutch fan... the only thing is, it feels almost like though the truck is revving really high, it is still moving really slow, even though I rev it... kind of like the transmission is slipping or something. But as soon as the "roaring" sound stops... it has full power with no "slipping" anymore. There are no transmission issues with the truck, shifts fine etc. so does this have more to do with the clutch fan?

 

its normal they all do it i think its from all the oil being in the bottom of the clutch fan and it just has to lubricate itself again or something but mine does it and i'm sure others will agree

 

Thanks for the reply. Is it normal for the "slipping" feeling as well though? A better way to describe it is that it feels almost like it's in 4LO.

 

It may just be that the clutch fan takes some HP away while its fully engaged. If you have the electric fan in front of the clutch fan, then just remove the clutch fan. I have mine that way and I live in TX where it reaches triple digits all the time with no overheating issues.

 

Mayb try to take off the clutch fan and drive down the road and see if it still sounds bad. After I went threw my third fan I took it off and run without. My truck is a bit warmer but nothing to worry about.

 

my 98 is the same way I make it to the end of the block(about 1/4mile) and its fine. I remember my bosses 02 doing the same thing.

 

alot of vehicles do it. my truck, and all 3 of my parents fords do it too.

 

Yeah same here. Its common. As long as it stops after just a minute or two you're fine. I know my truck and my fathers both do it. Especially on cooler mornings with not much time to warm up or like you mentioned has been sitting for a few days.

 

yeah, the clutch fan does rob about 5 horsepower.. just be happy its not a class 8 truck clutch fan.. they rob about 45 horses

 

it is 1hp lost per inch of fan.