'91 4.3 question - harmonic balancer
 

My son has a '91, with the 4.3/automatic. I think his harmonic balancer is bad. When the engine is cold, it is quiet. When it has warmed up, there's a knocking sound that isn't a bearing. I'm thinking the balancer is the source of the noise. He's down on money, so I'm trying to offer free suggestions so he won't do something stupid...well, anything else stupid.

Any easy way to know that the balancer is the issue?

Re: '91 4.3 question - harmonic balancer
 

I doubt the balancer is the cause. cracked flexplate?
a rod knock can be confirmed by shorting one cylinder at a time. when it stops you have found the bad rod.