Engine cooling fan won’t engage

[Worldsworstfish]

I seem to have a properly operating solenoid as it vents when I shut power off

The fan clutch will not engage. I pulled the airline going to the fan off at the fan shroud, and I can spin the fan by hand. I assume from all the posts I have read that it should be locked up, with the air removed.

Guessing bad clutch, assembly. Is there any easy fix solutions or is it just a replace the clutch situation?

 

[TomTime]

There two different clutch’s for the FMTV. Check to see if you have the fan that is attached with bolts or the one that is attached with nuts screwed onto studs.
What truck model and year do you have?

You can get a clutch rebuild kit, that’s what I did to mine, it works great and you don’t have to buy a new clutch. It’s not that hard to do just a little time consuming.

You need to remove the top radiator hoses (a small hose and a large one), intercooler lines, air line, the top fan shroud and fan to get to the clutch.
They say if you have the old style clutch that has the bolts that attached the fan you should replace place it with a the newer style that uses the nuts on studs.

Apparently the older one has a gasket that deteriorates and lets the fan wobble, which can cause damage.

I believe some of the smarter members on here can tell you more about the older vs the new one, then I can, and more!


Here is @Ronmar, with a YouTube video explaining the old style. Great video.

Here are some photographs of the engine when I did mine.








Sorry, I didn't take photographs of the rebuild, I don't know why though.

Here is a video from Helicool's Helipad showing the fan clutch. Starts at 7:18

There are YouTube video's showing how to repair a clutch. This is the video I used before repairing my clutch. The only difference in this video, the fan clutch has a rear air seal whereas the FMTV's has a front air seal. You'll see that when you go to remove the air line to the clutch. Except for that it's the same repair with the correct kit.

I believe the kit I used was the 8000SKL, but check and verify that before you order one.

Product Detail

Kit Masters Part #8000SKL - Replacement for OEM Part #s: 9908401, 1681030c92, 10330543502, KMN208000SKL, ABPN208000SKL, FLT8000SKL

kit-masters.com

EDIT: Just a note, after you take the front air seal off the front of the fan, remove the fan and replace the air seal so you can add air to the clutch so you can release the clutch and rotate the out portion to line up the holes to take the bolts out to get the whole clutch off.

Good luck.
Tom.

 

[Ronmar]

What @TomTime said. I would add that if you have the old style fan clutch like seen in my video, there is no rebuild kit available for it and you will have to upgrade to the new style clutch. Unfortunately you will also have to replace the fan as the new clutch does not interface with the old fan… Also unfortunately that will probably close in on ~$900 in parts…

The bearings in my fan are not in great shape and will need replacement. I of course have the old style So I am staring down the barrel of the same cost cannon. I have been researching/exploring using a heavy duty viscous coupling that should be lower cost and should allow me to use my existing fan with perhaps a little modification. Half the cost, no more electric over pneumatic control system and should be perfectly adequate for my needs…

 

[GeneralDisorder]

I will add that these fans are plastic and it's not a forever material. My 2008 fan already had small cracks forming in the plastic that had yellowed significantly from age. When I did my AC belt pulley I installed a new clutch and a new fan.

Having a fan blade snap off and get sucked into the radiator would be a lot more costly of a failure than a new fan blade. I found a new fan blade assembly on eBay for like $160.

 

[aw113sgte]

What @TomTime said. I would add that if you have the old style fan clutch like seen in my video, there is no rebuild kit available for it and you will have to upgrade to the new style clutch. Unfortunately you will also have to replace the fan as the new clutch does not interface with the old fan… Also unfortunately that will probably close in on ~$900 in parts…

The bearings in my fan are not in great shape and will need replacement. I of course have the old style So I am staring down the barrel of the same cost cannon. I have been researching/exploring using a heavy duty viscous coupling that should be lower cost and should allow me to use my existing fan with perhaps a little modification. Half the cost, no more electric over pneumatic control system and should be perfectly adequate for my needs…

Bearings tend to be standardized, I spec them all the time for work. If you can get an id, OD, width, and type (pictures may be sufficient) can probably find replacements.

 

[Worldsworstfish]

Thank You to everyone especially Tom. Winter got here early, so next week when fall returns will go take a look. Really appreciate everyone’s help.

 

[Worldsworstfish]

Well I have a working fan!

The issue turned out to be a simple no cost solution. When I went to remove the nut on the-rotating air fitting on the front of the fan the clutch engaged. I went ahead and removed the fan and replaced the water pump drive belt while I was that far in. When I pulled the rotating air off I found that the o-ring was in bad shape and had deteriorated. The inside of the rotating air assembly was black and sticky. I cleaned everything up installed a new o-rings with some vegetable oil and put everything back together. Everything works as it should.

This could be what is happening with some of the posts saying that a couple good bangs disengages when the clutch is opposite of my situation.

One thing that I noticed with my situation is that if I overtightened the nut on the air inlet, my clutch would disengage. I just tighten the nut until the fan started to freewheel and backed it off a quarter turn. It could have been that the nut being too tight on the air inlet housing was the problem and I could have just reached in and loosened the nut, I would not had to take the entire thing apart. I needed a new water pump belt anyway so it was worth the extra work.

Thanks for all the help!