How do you torque the crank bolt properly?

Edis06

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So a got a healthy 8K miles out of my makeshift keyway fix, but again, it failed. The bolt keeps slipping out!! If the bolt would stay torqued, there would be no problem. I used Permatex Red and a stronger bolt as GM recommended (10.9).

Now I am having the keyway welded then dremmeled out to fit the key, rather than using a "steel epoxy" putty. Should be a better fix. Welding the balancer to the crank didn't work - even with the bolt torqued, it loosened up and shattered the weld like glass.

So, going forward, how would anyone recommend torqueing this? I have another NEW harmonic balancer (6.2), a new updated bolt (the material looks a little different than the one I had custom installed but it's still 10.9). new key and will be getting the keyway done tonight hopefully.

Should I use an 90 degree impact? Or, is there a way to lock the engine and use a conventional torque wrench?

Before the comments start, I have exhausted my efforts in getting a new engine or even a rebuild with a new crank. Nobody calls me back. I'm willing to spend thousands getting this done and nobody wants my money, not even the big Hummer shops.

Gotta get this truck back on the road.
 

TOBASH

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Please measure the crank to balancer diameter with a vernier caliper or micrometer IF you get a chance.

And thanks for your reply to my thread!!!
 

A Seabee

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So a got a healthy 8K miles out of my makeshift keyway fix, but again, it failed. The bolt keeps slipping out!! If the bolt would stay torqued, there would be no problem. I used Permatex Red and a stronger bolt as GM recommended (10.9).

Now I am having the keyway welded then dremmeled out to fit the key, rather than using a "steel epoxy" putty. Should be a better fix. Welding the balancer to the crank didn't work - even with the bolt torqued, it loosened up and shattered the weld like glass.

So, going forward, how would anyone recommend torqueing this? I have another NEW harmonic balancer (6.2), a new updated bolt (the material looks a little different than the one I had custom installed but it's still 10.9). new key and will be getting the keyway done tonight hopefully.

Should I use an 90 degree impact? Or, is there a way to lock the engine and use a conventional torque wrench?

Before the comments start, I have exhausted my efforts in getting a new engine or even a rebuild with a new crank. Nobody calls me back. I'm willing to spend thousands getting this done and nobody wants my money, not even the big Hummer shops.

Gotta get this truck back on the road.
Use a chain wrench to hold the crank pulley while you torque the bolt. use a old timing belt to protect the pulley from the chain wrench. If your crank is shot, just weld the pulley on, worry about it when you go to replace the crank
 

TOBASH

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You can open the plate that covers the flex plate and torque converter and hold the flex plate making sure not to bend it. You can look up online to see if there are devices that will mesh with the gear to lock the flex plate as per the duramax suggestion by aseabee
 

Edis06

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The duramax has a ton of flywheel locks on the market, but I don't see how to safely lock this flywheel. The shroud next to to the starter doesn't seem sturdy if I remember correctly (just a metal plate) and I'm not comfortable with sticking a pry bar into only one tooth of the flywheel and applying 200+ ft/lbs of torque. And yes, they moved the 160 ft. lbs. of recommended torque to 200-220 when the crank bolt was updated. The flywheel locks typically have multiple teeth to spread the load over a greater area minimizing potential damage.

As for locking the pulley, that's not possible because the pully attaches to the balancer and the bolt needs to be torqued prior to the pulley being installed. Also, if you lock the pulley/balancer then tighten the bolt clockwise, you're twisting the pulley counterclockwise against the woodruff key causing the problem all over again. The crank itself needs to be held to torque it properly.
 

A Seabee

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The duramax has a ton of flywheel locks on the market, but I don't see how to safely lock this flywheel. The shroud next to to the starter doesn't seem sturdy if I remember correctly (just a metal plate) and I'm not comfortable with sticking a pry bar into only one tooth of the flywheel and applying 200+ ft/lbs of torque. And yes, they moved the 160 ft. lbs. of recommended torque to 200-220 when the crank bolt was updated. The flywheel locks typically have multiple teeth to spread the load over a greater area minimizing potential damage.

As for locking the pulley, that's not possible because the pully attaches to the balancer and the bolt needs to be torqued prior to the pulley being installed. Also, if you lock the pulley/balancer then tighten the bolt clockwise, you're twisting the pulley counterclockwise against the woodruff key causing the problem all over again. The crank itself needs to be held to torque it properly.
I'm not familiar with the 6.2, but I think I know what you're saying. you need a wrench like this that will hold the balancer while you torque the crank bolt

maybe you can fabricate one from a nice thick piece of 3 or 4" flat stock. don't worry about the square drive hole. just lay it out using your balancer and pulley as templates then drill, torch or plasma cut as needed. I'm picturing about a foot long, big hole in the middle, 2 or 4 bolt holes and taper the other end so you can stick a cheater pipe on it if need be, or make it long enough to hit the floor and go to town
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A Seabee

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there's likely hundreds of these made for this exact task by Kent Moore or OTC laying in a conex box in Iraq that nobody knows or cares what they're for. probably using them as a charm necklace for their camels
 

Retiredwarhorses

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Never had this in 30yrs, you have something else going on...very well the crank end is out of spec from when the key broke and spun, just my .02 cents. Call my shop if you like.
 

A Seabee

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Never had this in 30yrs, you have something else going on...very well the crank end is out of spec from when the key broke and spun, just my .02 cents. Call my shop if you like.
Yeah, good point for sure. shouldn't the balancer need to be pressed or pushed on with a tool? if a new one just slides on then for sure the snout of that crank is out of spec. I just re read the OP, and it says he tried to weld it and it still came loose and shattered the weld. who knows how long it went with the bolt loose originally before it sheared the key and buggered the keyway. but getting it torqued properly may buy him some time
 

Retiredwarhorses

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Yes, it is press fit, I have the installer tool, it should not just slide on, or off for that matter.
welding is a problem, the cranks are forged and the metal properties will change with the migs heat and un-heat treat the area if not hardened correctly, also probably impossible to do in the truck.
IMO, the bolt does not do the vast majority of the holding of the balancer, the pressing on of the pulley and key does all the work. Same applies for PS pulleys and other such pressed pulleys.
 

Edis06

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Hold on guys, lemme catch up.

Ok, the keyway broke due to the old stripped out crank bolt that was in the truck when I got it. It was the softer bolt, which was actually recalled on the civilian 6.2s and replaced with the updated bolt for this same reason.

The balancer isn't spinning freely - when I repaired it with steel putty, I had to use a remover to remove it and an installer to install it. The new balancer fits very snug and requires quite a bit of effort to install even with an installer.

When the bolt fails, or the person who performed the last major service failed to torque it down properly, then the balancer will put way too much force on the keyway. The local diesel shop sees it all the time. Sometimes the woodruff key shears, sometimes the keyway breaks. In my unfortunate case, the keyway is broken.

Since the old bolt was stripped and outdated, I replaced it with the newer 10.9 hard metal one. Unfortunately my biggest issues with the repair have been 1) the epoxy putty simply won't hold, and 2) I cannot torque the bolt enough to get a good, permanent bite. I have hammered it tight but nothing near the 200 ft. lbs., I suspect.

The good news is that I do have someone coming in to weld the keyway, which I will drip down to match the shaft. This should be a more permanent fix, if I still have trouble finding someone to rebuild or replace this engine.
 
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A Seabee

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well, at this point you really only have 2-3 options
find or make a tool to hold the crank in order to achieve your 200 ft lbs. of torque and give it another try
or
get a new crankshaft

lot of dynamics at play right there. torsional, vibrational, heat, etc. it's a 6200 cc beast that's propelling a 5-6000 pound machine and turning a bunch or accessories. the keyway and key can't have any slop at all
 
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