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Fan clutch? - Printable Version

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Fan clutch? - JimT - 06-22-2020

Started the day at home with my engine fan stuck in high gear. Hooked up Insite, fan wasn't supposed to be running. Checked the air supply and switch. There's air going to the fan and the switch appears to work properly.

So, before I run off to buy parts and start tearing stuff apart, anything else I should be doing/checking? Also, does the radiator/coolers need to be moved or is there another way to work on it without moving them?

I personally washed the truck last night. Brush and garden hose. Gently sprayed down the engine, could that have affected the fan? It was near the end of the day and this morning things were still a bit damp.

Anyway, any input would be appreciated.

Oh, maybe a stupid question, but is it safe to drive the truck around with the fan constantly on? I'm supposed to be picking up a load for delivery tomorrow. 400mi round trip total distance. My initial thought is no, cancel the load and fix, but what say you folk?


RE: Fan clutch? - Rtrucking - 06-22-2020

Maybe take a small hammer and tap the fan hub could be rusted together and just need to be ajar apart? But on my truck all I had to do is pull the fan and then pull the hub out to replace it, didn't have to pull the rad or cac to get at it.


RE: Fan clutch? - JimT - 06-22-2020

Never done this before, wasn't sure what needed to be removed for access. Looking at it I think I might be able to unbolt the shroud and push it back to get to the fan, then take them all out together. I'm actually contemplating taking an extra day or two to acquire and replace the crankshaft damper while I'm at it since it'll be pretty well exposed.

Oh, forgot to mention it's a 2012 Petebilt 587, CM2250.


RE: Fan clutch? - JimT - 06-22-2020

Tried the hammer, either i'm not hitting it hard enough or it don't want to budge.


RE: Fan clutch? - Rawze - 06-22-2020

(06-22-2020 )JimT Wrote:  Tried the hammer, either i'm not hitting it hard enough or it don't want to budge.

run truck and build the air up all the way.

turn truck off and as soon as it stops spinning, turn key back to run position withoput re-cranking truck. fan hub should still be released.

smack the fan hub metal parts with a decent hammer several times , almost hard enough to dent it. it should free up on you.

dopn't forget to turn off keyswitch in dash once it is free.


-- i have to do that to mine almost every time it rains and the truck is sitting a few days.


RE: Fan clutch? - Waterloo - 06-22-2020

I had the same issue after the truck sat, hammering did nothing, building up air pressure did nothing... So, I went and found some 1/4" airline, same size that powers the clutch, put a push pull fitting on one end, and a male shop air fitting on the other end, FleetPride hooked me up, to fit my little Lowes 90 psi air compressor. I hooked it up at the solenoid by the fire wall and gave her a shot, worked like a champ. If I remember correctly I did not even have the motor running when I did this, I think it popped and I fired up the motor, no more sticky fan clutch. Anyways, it did work, and building the part was inexpensive vs a new fan clutch.


RE: Fan clutch? - JimT - 06-22-2020

Thanks guys. As obvious as it should have been, my dumb butt was trying to free it with the key off. yup... Anyway, before Rawze or Waterloo responded I found this older post which clued me in to my folly.

Once the key was on it only took two little taps and all was good again. Checked a few times and it engages/disengages just fine. Guess I'll have to go out and work today after all...

Washing the truck last night I was debating whether to even lift the hood. Somehow I know I'd have some sort of problem. Oh well, lesson learned!

Thanks for the responses and hope this helps someone else in the future.


RE: Fan clutch? - JimT - 06-23-2020

Got to thinking about this a bit more while rolling today. If water/moisture is getting in to some part causing rust/corrosion, wouldn't it be easy to just give it a spray of something like WD-40 (or whatever your favorite is) white lithium grease? I use this stuff regularly on my ratchet binders and some other things, seems like it would protect the area from moisture while adding a nice little coating of grease.

I don't see how it could hurt, but would it actually be helpful? Any thoughts?


RE: Fan clutch? - Rawze - 06-23-2020

not really, as it is friction that keeps it spinning once it engages.