Vibration issue

Ground the crank?

Whaaat????? cranks cannot be turned down as no such as oversize bearings, they can be welded up and ground back to spec and are rebalanced. If the injectors(air/fuel) where not serviced one can be lean and cause a cylinder to drop out and cause a vibration. This may be reason it failed as injector has a problem, you always service(flow/balance) injectors on a DI/EFI motors during a rebuild.

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faztbullet said:

Ground the crank?

Whaaat????? cranks cannot be turned down as no such as oversize bearings, they can be welded up and ground back to spec and are rebalanced. If the injectors(air/fuel) where not serviced one can be lean and cause a cylinder to drop out and cause a vibration. This may be reason it failed as injector has a problem, you always service(flow/balance) injectors on a DI/EFI motors during a rebuild.

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Thanks for you input, I'm taking boat in today for yet another look !!!

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galamb said:

Bad prop? bent prop shaft? bent drive shaft? a dozen other things.

Why was it rebuilt and what does "completely rebuilt" mean??

New pistons AND rods or reused the old rods (possibly one was a little bent). Replaced the crank bearings? Ground the crank? Replaced the crank?

Like a tire on a car at most speeds it may seem fine but at a certain speed the (defect) is noticeable.

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