V1 LSJ Harmonic balancer broken key

[MR.812]

So i was driving today and lost my boost. When i returned home the harmonic balancer was not turning. The engine is still running fine. So can i just replace the key or do i now have other issues? i removed the balancer bolt and i can spin the balancer freely.
Thought?

 

[Trail_Creeper]

Any idea on what cause the key to potentially break? Does the supercharger still spin?

 

[MR.812]

Everything is spinning fine. The bolt was loose on the balancer.

 

[Trail_Creeper]

Lock her down with some loctite and run it

 

[Desert Sasqwatch]

If the engine was running and the balancer/pulley was not turning - and it didn't slip completely off the nose of the crankshaft - it is likely a broken or missing key. Running 'loose' could damage the keyway slot in the crankshaft nose. I would pull it, check for damage and install a new key before torquing everything back up. The bolt in the end of the balancer is meant to keep everything together, the key is what prevents the balancer from spinning on the crankshaft nose - without the key the balancer will keep slipping no matter how much torque you put on the bolt. Better to be certain than to end up with something expensive to fix in the future.

 

[MR.812]

Thanks
All ready getting ready to pull it.

 

[lksohm]

That is a torque to yield bolt. It is meant to be replaced every time it is pulled off. Many people re use it but if you had issues in this area it might be worth it to replace the bolt.
Fixing a damaged crank is an immensely bigger job than this.
Just my $0.02

 

[MR.812]

Thanks

 

[MR.812]

Looks bad, The crank did clean up the keyway is fine. Looks like the hormonic balancer came loose and sheared the key. Looks like a new balancer and key.
thoughts?

 

[Desert Sasqwatch]

Oh that's not looking good. Can you get anymore photos of the crank snout and the inside of the balancer? That single photo of the actual damage is limited in visual information.
You may be able to use a fine tooth file to clean up the edges of the keyway in the crank and use some emery cloth to clean up the scorching and spaulling on the snout. It's hard to tell how large/deep the gouges are on the edges of the keyway slot - this may be a limiting factor for reusing the crank. Additional photos may show other things of concern. Sorry about this.

 

[Gtstorey]

How much of the holding on the harmonic balancer is the key way and how much is press/interference fit? LS engine is all interference fit without a keyway.

Depending on how the harmonic balancer sits on the crank, you might could drill from the end and insert a 1//4" pin in the end to help keep it from slipping. LS Crank Pin Kit - LS1 Swap by LSX Innovations
Probably not the right size but not to hard to fab your own.

 

[MR.812]

Great news......
Replaced the key, bolt and balancer after cleaning up the crank. Everything is working as it should. Only the tip of the key was broken.