My son just bought a K10 with a freshly built 1984 - 355. The motor sounds great but there are a few concerns.


I noticed that the balancer has a wobble and the starter didn't sound good. Recently he pulled the inspection cover thinking that the starter wasn't shimmed properly only to find that the flex plate has a wobble too! He checked to insure that the flex plate wasn't cracked between the webbing and it is not. This makes me think that the crankshaft may be bent. I can't see a crank being bent unless it was in a bad crash or dropped, and if dropped not sure both ends would wobble. I'm hoping that its just poor assembly but I'm a bit out of my wheelhouse on this one. The truck is a '85 and we're told that the motor is an '84 so we know its out of something else. If it were just rebuilt, and he has the receipts that he hasn't gone through yet, surely that would have been checked during the build.


I've been around Chevy engines since I was a kid, but I don't get down into the weeds as deep as a crank. What can you add to my situation?

 

I'd suspect the flywheel

 

No flywheel, just a starter ring, its an automatic. Unless you meant the harmonic balancer.

 

Ok, flex plate

 

You won't bend a crankshaft, you might twist one, but I don't think your engine would do that

 

So based on the above do you think we need a new flex plate and damper? I wonder if the damper is just not seated properly? Changing the flex plate may be a chore being a 4x4 and having a transfer case.

 

Drop the dust pan, make sure the bolts are tight