wobbly crank pulley

[kapnklug]

So I've owned my M1009 for a couple months now, and just noticed that the crank pulley has a definite wobble in it. The engine runs great, with no vibration,
so I'm guessing this has to be just a bent pulley (right?!?) but it's wearing out the belts. Anyone got a crank pulley they'd like to sell? Its 8" dia at the outside (two grooves) and slightly smaller on the inside groove (three altogether).

 

[Westech]

harmonic balancer is starting to come apart. very common thing to happen to the 6.2. Time to replace it before the crank brakes.

 

[Rustmaster]

I hope that is all it is. I just pm'ed a guy today who had a vibration issue and relayed my story. My 1008 ate the key in the key-way on the balancer before i could fix it and i had to get a new crank and balancer, so i rebuilt the darn thing. I didn't catch it in time because I had just bought it and was on the way home with it. The dude i got it from assured me it was just a trans. mount cause he just put in new motor mounts. That was the ten mile maiden voyage that cost me a lot of scratch.

 

[Tanner]

So I've owned my M1009 for a couple months now, and just noticed that the crank pulley has a definite wobble in it. The engine runs great, with no vibration,
so I'm guessing this has to be just a bent pulley (right?!?) but it's wearing out the belts. Anyone got a crank pulley they'd like to sell? Its 8" dia at the outside (two grooves) and slightly smaller on the inside groove (three altogether).

Wobbly 6.2/6.5 GM crank pulley equates to the pin being pulled & the lever being released on a M67 - it's only a matter of time before something goes 'BOOM!' in a bad way... and takes other stuff with it.

'Tanner'

 

[kapnklug]

Wow thanks for the heads-up, guys -- this is supposed to be my daily driver! This would make a good addition to the CUCV FAQ

 

[motormayhem]

Mine is doing the same. How expensive is a harmonic balancer and how hard it it to replace? Can I do it in my driveway? It has been like this for almost 6 months since I got it.

 

[Rustmaster]

You should be fine in the driveway you are in AZ so you won't here to sweep the snow up first. I've been praying for 70Deg.
I can't remember how much the balance is by itself. You can see from my post above I ran into a bit more than i wanted to.
Loosen the belts, remove the crank pulley, loosen the big center bolt, than try to remove the bal. The center of the bal. is the tough part I can not remember if i used a puller or if it wouldn't fit because of the radiator. Once off inspect the crank and use a new key in the key-way. than reassemble.

 

[motormayhem]

You should be fine in the driveway you are in AZ so you won't here to sweep the snow up first. I've been praying for 70Deg.
I can't remember how much the balance is by itself. You can see from my post above I ran into a bit more than i wanted to.
Loosen the belts, remove the crank pulley, loosen the big center bolt, than try to remove the bal. The center of the bal. is the tough part I can not remember if i used a puller or if it wouldn't fit because of the radiator. Once off inspect the crank and use a new key in the key-way. than reassemble.

So it isn't to difficult to do in the truck?

 

[kapnklug]

I'm now midway thru the job -- I've removed the old balancer. NAPA gets $90 for one, and I decided to replace the crank front seal at the same time, for another $10. It's taking three days to get one, so I'll post a follow-up on the installation.
You can definitely do it in your driveway (that's where I'm doing mine). You'll need a good-size, screw-in type puller, like a steering wheel puller. That was definitely the hardest part of the job, getting the balancer to pop off; the clearance from the puller mounted on the balancer to the radiator shroud and fan is pretty tight, and it's pressed on really deep, at least 2". I also had a lot of trouble keeping the engine from rotating while removing the big center bolt, but discovered that a long 5/16" allen wrench can be inserted (small end) into the drilled holes in the balancer at the 9 o'clock position, from the rear, then rotate the crank until the long end jams perpendicular into the motor mount crossmember. On assembly I'll use the same trick in the 3 o'clock hole. But that's for sunday's post...

 

[motormayhem]

Well I inspected my harmonic balancer today and the wobble is only on the pulley not the harmonic balancer. I tried to wobble it by hand and it seems to be nice and tight. The balancer has no visible damage except for a small polished line from where a piece of braceting was just barely rubbing when it was rubbing, but it sisn't cut into it, just posished that spot. What is the best way to tell if it is time for a new one as I don't have much extra cash at the moment.

 

[hobie237]

Mine was showing slight decay, so rather than replace it out of need sometime in the future, I replaced it within weeks of first getting the truck. It's a pretty common issue with the 6.2/6.5, and really ANY balancer of this age. The difference is that diesels need more balancing than gassers, so they self destruct faster if/when the balancer goes bad. I think I paid around $60 at the local Advance Auto, but I really don't recall how much it was. Did need a puller (which I had, but others may not) and a torque wrench that could handle the 200 ft-lbs required to put the thing back together. And a friend to jam the flywheel with a prybar while I put 200 ft-lbs on the bolt. You're going to want a torque wrench that goes up to at least 250 ft-lbs, because they're not accurate when at the extreme end of their scale.

 

[reddogkaiser]

One fast and easy test is to mark a straight line from the inside of the balancer to the outside with a black marker and then take it for a ride, if the line shifts and is offset the balancer is bad and is a ticking time bomb!! You DO NOT want to have it come apart because it does terrible things to ENTIRE front of your motor and radiator!!! Don't ask how I know!
A balancer is a lot cheaper than a radiator, power steering pump and everything else in the way of that heavy little weight going very fast when it separates!!!!

 

[hobie237]

Even if the two halves aren't (yet) slipping against one another, one can press around the rubber interface between them and see if the rubber feels new/pliable or old/degraded/falling apart. If the latter, even if it's not yet slipping, it's likely that it's not doing it's full job of balancing, and diesels need that balance to avoid shattering the crankshaft. One could argue that just busting up the radiator and accessories was getting off easy.