FMTV Water Pump Belt Replacement

[NDT]

I tackled this today as my belt was OE Cat from 1998. That's runnin' on borrowed time. As usual, this was not a simple task. Yes the fan blade has to come off. If you are familiar with working with fasteners you cannot see, you can unbolt the fan by reaching through the blades. Otherwise, the shroud has to come off, and also the charge air cooler lines. That makes the task much simpler. The belt is also a bit tricky to get over the harmonic balancer. You'll figure it out, but at first I thought it would not go over it. I would suggest you do this PM before the belt shreds and you are doing this on the side of the road. That would suck.

 

[dmetalmiki]

Fact is, the older you get the harder these jobs (seem to) become. In fact As you recommend I now make sure these sort of tasks are carried out after regular checks and before making a journey "in doubt".

 

[Andyrv6av8r]

NDT
A question about your fan assembly; with everything bolted up tight to the clutch, can you man-handle the fan and turn it? My 1079 had the fan hub wallowed out when I got it and I ended up making a new Adapter/hub where the rubber compression piece is eliminated. If you look in the TM's, the services ditched the rubber piece also and went to a rigid bolted setup.

 

[NDT]

Andy, yes I could turn the fan without turning the crank. I was worried I would snap off a blade though. Good to know about the design change, I had not seen that.

 

[Lmtv772]

Do you recall the wrench size? it's always good to know the size on hidden bolts before

 

[NDT]

There are 6 ea 5/16" socket cap screws that take a 1/4" hex wrench if I remember correctly.

 

[Lmtv772]

Did you replace the Alternator belts as well? Can you remember the part number or where you bought it from?
thx

 

[NDT]

Did you replace the Alternator belts as well? Can you remember the part number or where you bought it from?
thx

Yes, the alternator belts are Gates 9580, I got them at the local auto parts store.

 

[spankybear]

Thank you NDT!!! You are awesome and have saved me a headache. Just know it's going to be a PIA to replace!

Speaking of Gates... are they made in China now?

 

[coachgeo]

Thank you NDT!!! You are awesome and have saved me a headache. Just know it's going to be a PIA to replace!
..

For future reference the belt part #'s (and many other part #'s) are in the yellow parts spread sheet linked in the sticky/pinned thread at top of this forum and probably in Guido's sheet too. (Awesomeness)

 

[spankybear]

For future reference the belt part #'s (and many other part #'s) are in the yellow parts spread sheet linked in the sticky/pinned thread at top of this forum and probably in Guido's sheet too. (Awesomeness)

Yes sir... the parts 24P TM is also an awesome source part numbers

 

[Reworked LMTV]

Honestly, for a little more effort, pop the AC pulley on for a later build and change that front engine seal. Easy peasy if you are already in there.

 

[tennmogger]

If you make up a short pigtail to put shop air pressure on the fan clutch, it is easy to turn.

 

[spankybear]

I am having a hard time getting my fat paws and arms in... I took a look and has anyone tried to take the bottom shroud off? Kind of looks easier to take off if you can get it past the drain on the bottom.

 

[Ronmar]

Andy, yes I could turn the fan without turning the crank. I was worried I would snap off a blade though. Good to know about the design change, I had not seen that.

When you turned the fan by hand did it slip where the rubber spacer is, or did it slip at the clutch? I have put quite a bit of force on mine and it does not slip/rotate...

I think the sandwiched rubber was done as an attempted safety to keep something that jams the fan from completely destroying it by sacrificing the rubber ring...

There are a few who have posted on here about removing the rubber material entirely. There are holes on the fan disc that line up with machined holes on the clutch/hub and the two pieces can be hard bolted together without the rubber with some different/shorter hardware... This needs to be done before the rubber ring fails because as soon as it does, the fan dances around on the aluminum center hub and destroys the holes in the fan disc as they are close to the edge of the center hole.

when this happens you have to replace the whole fan/clutch assembly with the new style, or find an old style assembly to re-use...

 

[Third From Texas]

...or it launches thru the radiator.

 

[Ronmar]

...or it launches thru the radiator.

After the rubber descintigrated, the fan would have to rattle around in there for quite a while to wallow out the fan center hole big enough for it to get past the lip of that center hub.

I think the ones that go thru the radiator are the ones where the bearings, retainer or center shaft in the freewheeling portion of the clutch assembly fail, releasing the fan and front half of the clutch to propel themselves forward into the rad...

 

[Third From Texas]

Ah, rgr all.

I just remembered my first truck's original radiator had been "airyated" when the fan fragged.

.