Engine rattle under load

[cheers731]

Hi All,
It's a 92 Four Winns 205 Sundowner, 5.8L/Cobra setup. The engine starts vibrating at 800-1500 rpm with propeller engaged. No rattles at neutral any rpm or higher than 2000 rpm with propeller on. Please help with troubleshooting and fix.
Thanks,
Frank

 

[vfrkent]

Re: Engine rattle under load

Check your gimbal bearing and U joints, sounds like one or both are worn.

Regards,
Kent

 

[cheers731]

Re: Engine rattle under load

Thanks for the advice. The gimble bearing is new done by the shop and only has 30 hrs on it. I guess the u-joint is the next to check. Just out of curiosity, why the rattling goes away at or above 2000 rpm?

 

[vfrkent]

Re: Engine rattle under load

It could be that it hits a harmonic that cancels out the vibration.

Regards,
Kent