843 - heavier vibration at max RPM

I notice a heavier than normal vibration at top throttle. It goes away at medium and low throttle. I'm thinking it might be the starter rattling, it's mount design is such that it sits loose on the back end of its bracket, probably to keep it from absorbing shock. Everything else on the engine seems to be running smoothly, nothing out of balance, the drive belt is in line...anyone have experience with this?

A 843 has a U-joint assembly that drives the pumps not a drive belt. I'd suspect that the U-joints are getting ready to come apart and that's the vibration you're feeling. If they do explode they will normally take a some expensive parts with them.

OldMachinist said:

A 843 has a U-joint assembly that drives the pumps not a drive belt. I'd suspect that the U-joints are getting ready to come apart and that's the vibration you're feeling. If they do explode they will normally take a some expensive parts with them.

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Exactly what is was...U joint was shot. Thanks for the tip OM!

brennandc said:

Exactly what is was...U joint was shot. Thanks for the tip OM!

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Glad you got it before it took out any pricey parts.