V-6 Vibration - What can it be?
 

I have a 96 4.3 liter vortec V-6 that was just rebuilt and installed. New 0.030 over hypereutectic pistons and ground the crank 0.010. A local machine shop balanced the assembly as well and then I installed the components in the block and then into the boat.
There is a strange engine vibration above 2,000 rpm that was not there before and does not seem right at all.
What I am curious to know, is if the balance shaft has to be in a particulair position when assembling the motor? Anybody know or help?

Re: V-6 Vibration - What can it be?
 

Anybody????

Re: V-6 Vibration - What can it be?
 

Check out this thread, could be a similar issue.

http://www.offshoreonly.com/forums/s...d.php?t=105864

Dave

Re: V-6 Vibration - What can it be?
 

The balance shaft does have to be timed I beleive. On the one balance shaft motor I worked on it had a dot on the gear that had to line up at same time as cam and crank. It wasn't a chevy v-6 though.

Re: V-6 Vibration - What can it be?
 

Thanks Wobble - I will try to get a chevy motor service manual to get more details.

Gary

Re: V-6 Vibration - What can it be?
 

The balance shaft as suggested was the first thing that came to mind, how about motor alignment and ujoints on the drive??? :rolleyes:

Re: V-6 Vibration - What can it be?
 

Fountainatlast: The factory mounts and settings were not not disturbed. I think alignment is not the culprit. I beleive the U-joints are ok as well. Good questions though.
When I put it together, I did look to see if there was a mark on the balance shaft gear to align but did not find one. Without seeing a mark, I ignored it after that and put it together in "whatever" position.
If in deed this must be in a certain position, then it could be where the vibration is coming from. Will have to read up on this.