Maintenance Tip: CAT 3126 Water Pump Belt Replacement

[Native]

Yesterday, I went to replace the water pump V-belt (cogged) on our CAT 3126. I had removed the idler pully for the serpentine belt and loosened up the serpentine tensioner so that I could remove the water pump V-belt. I found that the darn belt would NOT fit around the harmonic dampener.


I was looking at having to remove the harmonic dampener! I was thinking this was a crazy design that required removing the harmonic dampener for a simple belt change!


I went back into the house to vent a little and literally cool down (hot day outside) and told my wife about it. She is my internet research assistant and in a few minutes she had the solution ... turn the belt inside out so that the cogs of the V-belt point outward! This provides an additional 1/2" in diameter to the belt.


I went back out to give it a try ... sure thing, it was enough to allow the belt to slip over the harmonic dampener.

[HazMatt]

Wierd!
But, if ya gotta go backwards to move forward, so be it.
Cha-cha-cha!

[banman]

Appreciate learning that on the front end -- looks like my bus is a twin to yours.

[Native]

Originally Posted by banman

Appreciate learning that on the front end -- looks like my bus is a twin to yours.

Indeed, it does!

[EastCoastCB]

Well when I get some daylight I'll give this a try. If I can get the old one off I'll take it to the Freightliner parts counter and get a new oem one and a spare.
Glad I caught it. I'll upload pics of how aweful this belt is. Its maybe THE worst belt I've ever had or seen on any machine. Was in the middle of the adjustment range and it was barely even holding the belt on the pulleys. I don't think my water pump was spinning nearly as much as its supposed to. Even maxed out on the adjuster its barely tight. Much better than before but still woefully worn out. Looks like its the original belt this bus left the factory with.
This is why I'm so methodical and obsessive about fixing mechanical stuff first THEN enjoying the bus once I get a handle on everything about mechanical condition.
Its easy to overlook this little belt. Anyone with a 3126 that hasn't checked theirs should get on it. Have a spare! This is one very important belt.

[Native]

The V-belt is available at most any auto parts store. I have our old one in the "mechanicals" box on The Beast right now. We can take a look at the number (and thus the size) tomorrow at the Skoolie Swarm when we get there if you like.

[Truthseeker4449]

Originally Posted by EastCoastCB

Glad I caught it. I'll upload pics of how aweful this belt is. Its maybe THE worst belt I've ever had or seen on any machine. Was in the middle of the adjustment range and it was barely even holding the belt on the pulleys. I don't think my water pump was spinning nearly as much as its supposed to. Even maxed out on the adjuster its barely tight. Much better than before but still woefully worn out. Looks like its the original belt this bus left the factory with.

Good to know I'm not the only one with a belt like this. Mine doesn't seem to be in too bad a shape but I've always worried about how the belt has some give with the adjuster maxed. I have a new one on hand anyway, I just have to find time to coax it. And find something to allow me to release the fan belt tensioner...

[EastCoastCB]

Originally Posted by Truthseeker4449

Good to know I'm not the only one with a belt like this. Mine doesn't seem to be in too bad a shape but I've always worried about how the belt has some give with the adjuster maxed. I have a new one on hand anyway, I just have to find time to coax it. And find something to allow me to release the fan belt tensioner...

half inch ratchet will take care of the tensioner.

[EastCoastCB]

Originally Posted by Native

The V-belt is available at most any auto parts store. I have our old one in the "mechanicals" box on The Beast right now. We can take a look at the number (and thus the size) tomorrow at the Skoolie Swarm when we get there if you like.

Yeah, they have it at the local parts stores. But the genuine stuff is the same price or cheaper.

[EastCoastCB]

I was afraid the belt flipping trick wouldn't work. The belt is FAR smaller than the damper.
Ugh... gotta pull the harmomic damper just for a routine belt change. Lovely.

[cadillackid]

fortunately that belt doesnt pull a lot of force so it will be many years before you have to change it again

[EastCoastCB]

Originally Posted by cadillackid

fortunately that belt doesnt pull a lot of force so it will be many years before you have to change it again

Yep.
Still gonna buy two just in case.

Kubla is on the way over in his MCI. If we can get the balancer off before the city comes with pitchforks all will be well.

[banman]

Originally Posted by EastCoastCB

I was afraid the belt flipping trick wouldn't work. The belt is FAR smaller than the damper.
Ugh... gotta pull the harmomic damper just for a routine belt change. Lovely.

Responding here after responding to your other post (on the same topic).

Forewarned is Forearmed -- not that I wanna be an octopus...

Could you measure the diameter of your balancer and post up so the rest of us know if changing the belt is gonna be harder than it outa be...

[Truthseeker4449]

Originally Posted by EastCoastCB

half inch ratchet will take care of the tensioner.

The engine looks bit too rusty for straight up brute force right away, need to soak her first. Probably need some heat too.

[Native]

Originally Posted by banman

Responding here after responding to your other post (on the same topic).

Forewarned is Forearmed -- not that I wanna be an octopus...

Could you measure the diameter of your balancer and post up so the rest of us know if changing the belt is gonna be harder than it outa be...

The OLD belt was smaller than the dampener, or at least the inner diameter of the belt. I struggled for a very log time trying to get the old belt off. My wife found the trick, I inverted the belt and it came right off. The new belt was just as easy.

[EastCoastCB]

Originally Posted by Truthseeker4449

The engine looks bit too rusty for straight up brute force right away, need to soak her first. Probably need some heat too.

BE very careful and soak the adjuster bolts with PB Blaster. If you break one off its not fun.

[EastCoastCB]

Originally Posted by banman

Responding here after responding to your other post (on the same topic).

Forewarned is Forearmed -- not that I wanna be an octopus...

Could you measure the diameter of your balancer and post up so the rest of us know if changing the belt is gonna be harder than it outa be...

I'll go take a pic and measure. IIRC its 13.5".

[EastCoastCB]

Originally Posted by Native

The OLD belt was smaller than the dampener, or at least the inner diameter of the belt. I struggled for a very log time trying to get the old belt off. My wife found the trick, I inverted the belt and it came right off. The new belt was just as easy.

They must have went to a smaller diameter damper on yours. Or your belt was larger than mine.

[EastCoastCB]

I got my belt swapped for a new one. Only one I could get was an AC Delco Professional. It cross-references and is the same size.
If/When I do this again I'll plan ahead more and have THE best belt I can get on hand.

IF the belt flip doesn't work for anyone else don't fret about the damper. Just get it out of there and get on with the job.

I just guessed/eyeballed it when setting the tension. Its a new and fairly stiff belt so I got it as tight as I could by hand. Its still got maybe a half inch of deflection in the middle but its way tighter than it was and feels right to me.

[EastCoastCB]

Originally Posted by EastCoastCB

I'll go take a pic and measure. IIRC its 13.5".