madkins

how do I know if vibration is due to harmonic balancer.
Thank you for any help.

1800Wing

I'd start by taking off the serpentine belt, crank the car and watch the crank pulley to see if it wobbles. That said I've never had one go bad on an LT1 motor....Buick and Chevy 3.8's yes but it's a different design.

There are 6 bolts ( might be 8, I don't remember ) that fasten the pulley to the crank flange ? ....9/16's

later, tiny

Silver96ce

There are 3 bolts that hold the balancer pulley to the crank hub. Make sure they are tight.

Also make sure the rubber ring sandwiched between the inner and outer parts of the balancer hasn't let go. This would allow the outer pulley to move around - in and out and also slip on the inner part of the hub.

MrJoelieC

Is it an automatic or standard?

The reason I ask is: it's easier to tell if an HB issue on an automatic. when you cold start the vibration is usually at it's worst... Usually, because the Rubber is harder until it heats... But the way I have been able to tell on other cars, and a 94 vette that had a bad one, is Put your foot on Brake and put it in drive or reverse...does not matter, ... When an automatic transmission is engaged it puts more of the crankshaft load onto the torque converter, thus reducing the vibration to almost nill...

On a standard, you pretty mutch are guessing with 1800Wing's instructions... The main pulley will be wobbling. If it get's bad enough it will cause the belt to walk forward and create a bunch of havoc. If the car has been sitting for a while and the rubber has not been flexing and just hardening from sitting You may want to consider just replacing it for peace of mind...

rfn026

This isn't a C4 harmonica balancer but you'll get the idea. On my car the rubber on the backside started going bad first. Check both sides.



Stay away from the aftermarket units. They can create problems and they really don't do anything for your car. Unless - You have a $50,000 race engine.

Richard Newton
Harmonic Balancers 101