M923A2 Fan Clutch Repair - Any Clutch Gurus Out There?

[gijoel]

Yeah, figured as much. Once I discovered the bent shaft, I knew it was over and a new one was in order. I pm the individual here who said he had a few but no response yet. Yes, ordered a new fan impeller. Other was damaged.

 

[gijoel]

Found a new fan clutch for $1100. Now to head back to Death Valley and work on the truck in +95F temps. Truck will have a new radiator, new fan impeller and new fan clutch. Hopefully this will all be behind me. Do plan to switch over to an aluminum radiator here shortly.

 

[Mos68x]

Had a catastrophic failure with the air clutch. The failure caused the radiator fan impeller to break loose and cut deep into my radiator. Regrettably, I was 100 miles away from any major help. In order to get it to a safe location, I manage to pinch and fold the fins/ribs of the radiator as to stop most of the water leakage. Every 3 to 7 miles, I had to stop and fill the radiator with water, but I manage to get it to a safe location 47 miles away. Upon closer examination of the clutch, it looks like the 8 set screws came loose and eventually failed causing the clutch to come part, thus, the failure. Anyways, I was planning to rebuild, but upon closer inspection, I discovered the center air shaft was bent by .018" from center line. So I’ll be purchasing a new or used. Here are pictures of the failure.
View attachment 681573View attachment 681574View attachment 681575View attachment 681576

And here I was thinking of just letting mine ride until I finished dealing with my tires. Doesn't look like that'll be an option now. I'd far rather get into it now and try to fix the problem before a catastrophic failure happens on mine since I live out in the boonies. BTW, love the look of the truck, do you have a a build record for the back? Or at least pics? I'm planning on doing a similar thing with mine, but with a 20' ISO instead.

 

[Boi]

To revive a dead thread in case anyone is interested:
The cause of fan-clutch rattle is due to the holes for the guide pins on the internal piston being slightly out of round, allowing a small amount of movement of the fan assembly relative to the belt driven assembly when the clutch is activated. It is only noticeable at idle when the RPMs of the engine are not perfectly stable, which allows the fan portion to jiggle back and forth making the rattling sound.

There seems to be two solutions to this: sleeve the piston, or sleeve the pins. I opted for shimming the pins, and it has greatly reduced the excess play in the system.

 

[Steelreaper80]

I have a complete fully rebuilt fan clutch from Seco Parts and the new style shutterstat.....fan will not kick on at temp. Haven't noticed it until now. The truck gets up to 205 degrees in stop and go traffic....no fan kicking on.......Which should I check first?

 

[Jbulach]

I have a complete fully rebuilt fan clutch from Seco Parts and the new style shutterstat.....fan will not kick on at temp. Haven't noticed it until now. The truck gets up to 205 degrees in stop and go traffic....no fan kicking on.......Which should I check first?

Acuracy of your gauge… use an IR temp gun to check around on the engine block. Next the water pump, radiator, and thermostats by checking to see if the radiator is getting hot on both sides. If so then check the shutterstat by checking the temperature of the top inlet pipe around it.