Howdy, new member here. Recently purchased a 2004 Ford Ranger XLT 4x4 2-door extended cab that has solid bones but needs some TLC. My son and I are putting it back in shape and it will be his first car when we're done. When puttering it around town, it started overheating so we decided to go ahead and replace the entire cooling system. New radiator, hoses, water pump, fan & fan clutch. Previous owner had done a conversion to an electric fan, but it was done really poorly and there was no temp sensor to control the fan. He'd just wired it to the battery and put an on/off toggle switch in the cab. So we took that out and decided it would just be easiest to go back to the water pump driven fan.

Got all the parts out and went to start putting it back together. Everything was going well enough until we got to the fan clutch. The instructions that come with the fan clutch say to tighten the mounting bolts from the clutch to the fan to 15-20 ft-lbs. My small torque wrench is in in-lbs so I set it to 180 in-lbs and got to mounting the clutch to the fan. Problem is the threads on the clutch seem to strip before I can get to 15 ft-lbs. 2 or three will tighten down to spec just fine but then the other two will tighten down and before hitting 15 ft-lbs, the thread in the clutch will strip and I can't tighten it any further. It just breaks loose again. When I back the bolt out, it's got one or two clutch threads wrapped around it.

I've gone through three different clutches (two from RockAuto and one from AutoZone) and it's always exactly the same result. I've checked my torque wrench settings 10 times over and made sure it's turned on. I checked my torque wrench against other bolts to make sure it wasn't malfunctioning and it works fine.

Is this normal? Is there a trick to getting these bolts tightened down to the right spec?

AutoZone has been great with returns. RockAuto I'll probably never buy from again - their return process is terrible.

 

I would check on the torque specs again the fan blade bolts should be 6 or 7mm and 5-8ft/lb
The clutch to water pump bolts are bigger and 15-18ft/lb sounds right

 

Thanks for the reply and advice. I did check several times to make sure I wasn’t doing something wrong. I also checked YouTube Videos to see what others were doing. There is an instructional video from 1AAuto specific to my Ranger that goes through the entire process step by step, and they also say tighten to 15 ft-lbs. I also felt that was a bit much but the fan is spinning pretty darn fast and moving a lot of air so, given that the instructions say 15 ft-lbs and so do the videos, I would think there's a reason for that spec. To my knowledge, there's no torque spec for the fan-clutch nut that mounts the fan to the water pump pulley. It's just "tight as you can get it".

Here’s a photo of my torque wrench setting

Torque Wrench Setting

And here’s a copy of the fan clutch install
instructions with the torque spec highlighted

Clutch Instructions

You Tube

 

I would stick to under 8ft/lbs, so crank it down to 96 in/lb
They will not unscrew, there is no torque to unscrew them just centrifugal force
If you have reservations then just add lock-tite to the threads, they will still be easy to remove at 5-8ft/lb

Yes, fan clutch nut is self tightening, lol, but tighten it down snug during install hopefully it will prevent it from getting too tight for next removal
4.0l V6 has regular nut threads
3.0l V6 has Reverse threads on that nut

On any engine it you look at the water pump pulley you can tell what threads clutch nut will have
Smooth pulley will be regular threads
Ribbed pulley will be reverse threads

 

I would honestly revisit the electric fan but do it the right way. I am currently in the process of collecting parts to do the electric conversion on my 01 w/a 3.0 because I am sick of having that mechanical vampire bolted to the front of my engine. Engine driven fans are fine on big diesel engines that have torque to spare, but the engine driven fan on my dinky little gasoline powered 3.0 is like dropping a battleship's anchor off of my tailgate when the fan kicks on & then is like revving the engine and dropping it into drive at 3k rpm when the fan cuts off, so the electric conversion simply has too many benefits to opt to stay with the mech fan, for me anyways.
Good luck & let me know if you decide to revisit the electric conversion the right way instead of the jack leggedy shadetree fu**ery the previous owner did.