Fan clutch bolts

[Suprman]

The fan clutch bolts seem to have a bad habit of coming loose. You have to air-to-release the clutch and you can rotate it to access the bolts. The fan clutch can come apart and throw the fan and front of clutch assembly. Its not pretty I have seen it twice in the last few months. One person said they heard a bit of rattling in front right before it came apart. I believe this issue can be detected by grabbing the fan blade, with the engine off of course, and giving it a shake feeling for excessive play.

 

[MaiNiaK]

I had the fan and water pump come off on a E350 I had. Destroyed my radiator.
Instant HP gain with a huge plume of white cloud .

Thanks for the heads up.

 

[Suprman]

 

[MaiNiaK]

Ouch. Did it take out the radiator?
Locktight normally works well on high vibration areas.
It's a must on Harley's

 

[NDT]

Those pictures seem to be of a failure of the rubber isolation mount of the fan? Not the clutch itself? Thanks for the heads up, one more thing to worry about.

 

[Suprman]

The one pictured did not hit the radiator. One that happened a few days ago threw half the clutch thru the radiator.

 

[Lmtv772]

Thanks for the heads up

 

[Monkeyboyarmy]

Are those the same set-ups that are on the A3 deuces?

 

[rchalmers3]

A periodic inspection of the belts, followed by a check in the fan deflection could possibly avoid the disastrous results depicted!!! Or maybe not!

Anyway, thanks for bringing up another point of failure on our beloved OD.

Rick

 

[Suprman]

I thought the first one a few weeks ago was just one of those "fluke" things but after hearing from someone else I know that the same thing just happened to it seems to be a possible issue. There are a lot of m939 trucks in private hands I haven't heard of one throwing a clutch and fan. In the scheme of things there really aren't that many lmtv trucks in private hands and for it to happen twice in a 2 month period is more than coincidence. I don't know too much about the inner workings of the fan clutch. I didn't see a rubber dampener though.

 

[Andyrv6av8r]

That's the old style fan/clutch assembly. The new and improved ones has studs in the clutch and no rubber damper.

 

[Suprman]

I believe the one that came apart had the current tm part number. It's all a learning experiance.

 

[Retiredwarhorses]

Looking at the pic, it appears to be similar to a HMMWV fan clutch, need hyd or air pressure to disengage to turn it to line up the bolt holes to remove or install. Locktite is a must...never had one come off a HMMWV though.
will have to check that bugger...

 

[lmtvjunky]

I've had the same problem, headed through the desert in the middle of a summer night, pushing a solid 3 hour drive when I heard what sounded like running over a tree branch or rabbit, pulled over and noticed my radiator dumping it's guts. The fan clutch came apart, went into the fan then threw itself into the radiator, and done! I managed to find a radiator, new fan and clutch and was able to duplicated the hose assembly for air supply. What a pain, I think the clutch bearing went out and lost the 1 nut that holds on the clutch cover .

 

[JMIL]

I had the same thing happen on my recovery from Fort Campbell. A really loud noise for a few seconds and then bang my fan sliced open my radiator.

 

[mkcoen]

Been a few months so need to bump for the LMTV crowd. Check your fans. I'm sitting on I-10 waiting for a wrecker.

 

[Suprman]

I have a feeling the fan clutch should be replaced with age/mileage. This has happened more times than its posted about.

 

[juanprado]

All the best on a speedy recovery back home.
Having been on the side of the road before, I know it sucks...

Stay well away from traffic / truck while waiting !

 

[Suprman]

The driveline on trucks need to be checked for play per the hinging test in the tm also. You will throw a driveshaft and cause alot of damage or worse have the driveshaft launch and hit another vehicle. I got 2 A1 tractors recently out of TX both needed U joints (too much play) and one a front driveshaft due to play in the slip joint.

 

[mkcoen]

The driveline on trucks need to be checked for play per the hinging test in the tm also. You will throw a driveshaft and cause alot of damage or worse have the driveshaft launch and hit another vehicle. I got 2 A1 tractors recently out of TX both needed U joints (too much play) and one a front driveshaft due to play in the slip joint.

We did the driveline check with a magnetic dial indicator and was WELL within specs so I'm not worried too much about that.

We also just had the fan clutch off when putting the AC pulley on and thought everything looked good for it too. It is the old style clutch and fan so age may have been a factor. My main concern now is getting the 160lb radiator and air charge cooler out of the truck and then back in once repaired.