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Fan Clutch Issues

YBC Offroad

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Cologne, MN
So I noticed the fan is always locked in on my m925a2. I saw it wasn't normal. I also noticed the truck had like a knocking sound at idle. Like a metal on metal smacking sound. Took the serpentine belt off and it is quiet as can be. So I investigated further into the clutch as I think it is making the noise. So I took the air supply line off of the shutter valve. I spun the fan. It was locked in and spinning the entire hub. (Keep in mind belt is off). I put shop air to the air supply line and heard the faintest clunk sound from the clutch. I didnt see it move. Went to spin the fan and it spun separate from the hub. So now the fan is free wheeling. Disconnected the shop air and it still free spins. Seems like the clutch is locked up? It doesn't seem to be moving at all. Any ideas?
 

simp5782

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You can source all the parts to rebuilt it thru Ebay. Just use the TM to run the part numbers and nsn's. Could put some marvels mystery oil in the supply line and see if that helps free some stuff up. What happens is a little moisture gets into it and the gums and rusts up causing issues
 

simp5782

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Replacement clutch units are pricey. It is made by Horton. They are hard to come by replacement wise. NSN 2930012688752 Cheaper to rebuild it by far. Or atleast take it apart and lube everything up
 

YBC Offroad

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After reading those, I seem to be more confused. They are saying that they typically need air to engage the fan when I used air to disengage it. But then the nhc250 engine was brought up. So idk which one they are talking about but I need the 8.3 clutch info. The fan was always engaged until I put shop air to it and it disengaged the fan. Any input? Also, happy 4th!
 

Floridianson

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If I remember some use air to in gage some use disengage. I like the one the was replaced on my 920. It took air to disengage and I liked that one. If there was an air problem the default was to lock up and the truck could still use the fan to cool till the problem was fixed. There was no bolts that had to be put in to lock it up if a problem arose. As said above cheaper to rebuild if it needs it and myself I would do it before it comes apart and takes out the radiator worse case.
 
Last edited:

Swamp Donkey

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After reading those, I seem to be more confused. They are saying that they typically need air to engage the fan when I used air to disengage it. But then the nhc250 engine was brought up. So idk which one they are talking about but I need the 8.3 clutch info. The fan was always engaged until I put shop air to it and it disengaged the fan. Any input? Also, happy 4th!
The A0 and A1 trucks with the NHC250 only used Evans clutches. The A2 trucks with the 8.3L used about 3 different manufacturers. Horton and Evans were two of them. I can't recall the third one.

The Horton clutch is engaged without air and released with air. This created a failsafe so that in the event there was a problem, the fan would would default to engaged.

None of the Evans clutches did this. They were air to engage, and no air to disengage.

You need to figure out which one you have. The Evans clutches had a metal data tag on the side of the mount where it bolts to the engine. I can walk you through an Evans rebuild and point you to the parts you need. I don't know about the other 2 manufacturers though. Never messed with them before.

Honestly, from your first post, it sounds like it's working to me...just backwards from what you think it would. The description you gave would be correct operation if it's a Horton. It would be almost impossible for an Evans to operate completely backwards even if it was messed up.

Confirm the manufacturer and we can go from there.
 

simp5782

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Every A2 I have seen is a normally closed fan. Which means if it is engaged while it Is running and you hear your little tapping sound then maybe your shutterstat isnt letting air go thru to disengage it and then closing to remove air when it opens up at 200/205.

Yes all of the bigger NTC engine fans are normally closed meaning air to it prevents engagement and defaults to on in the event of air loss
 

YBC Offroad

Member
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Location
Cologne, MN
So I looked at it again after learning more about the location of the fan actuator. I looked where it was and it wasn't even hooked up Haha. Someone ran an air hose from the supply right to the fan clutch. This engaged it I assume because the valve must have not been operating properly. I have an Evan's fan actuator. I took it apart and I want to put new o rings in it and hook it up and see if it works. I put the temperature thing in a 190 degree pot of water and the rod extended like it should. I think it must have leaked so that's why they bypassed it. Any idea where I can get an o ring kit for a ca200046? Also, I believe it is a normally closed based on the construction of the valve.
 

YBC Offroad

Member
38
2
8
Location
Cologne, MN
So I figured out it's an issue with my shutterstat. I put all new o rings in it. Put it back together and when boiling in a pot of water, you can see the assembly moving but no air comes out of the out port. Ideas?
 

YBC Offroad

Member
38
2
8
Location
Cologne, MN
Anyone? I have all new o rings. No air leaks. Hook the inlet up to the truck and heat up the tip of the actuator. The little bump sticks out of the back but no air comes out of the outlet. What gives? Everything goes together nicely and moves freely. Idk what's going on. Depending on how far I seat the piece with 3 o rings, i can make it have no air flow or constantly have air flowing without the actuator operating. This thing is really starting to bother me. Everything moves like it should but theres no air flow. I really feel like there is an orientation to how these parts go back together but I dont know. Any ideas?
 

simp5782

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Shutterstat are junk. Period. Depending on if you have a normally closed or open clutch. It should let air thru or take air away if you have air going to it. So if you have air going thru it before you put it in the boiled water and the plunger retracts it should close the air off and let the fan clutch come on.

I get rid of the shutterstat. I go to a electric solenoid found on Ebay

RF993283U in Haldex. You would need to know if you have NO or NC clutch to know what switch you need. It is a better long term investment than the shutterstat. Plus is also gives you the option to use the clutch as an engine brake or faster cooldowns
 

noazhouse

New member
8
1
3
Location
Medford Oregon
If I remember some use air to in gage some use disengage. I like the on the was replaced on my 920. It took air to disengage and I liked that one. If there was an air problem the default was to lock up and the truck could still use the fan to cool till the problem was fixed. There was no bolts that had to be put in to lock it up if a problem arose. As said above cheaper to rebuild if it needs it and myself I would do it before it comes apart and takes out the radiator worse case.
I need that fan clutch is ther a part number mine take air to engage and is bleeding off all my air
 
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