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velvet drive 'knock'

H

hgput17

Member
Commissioned the boat today and took her for a little spin. On the way back into the harbor, started to notice a 'knocking' from the bell housing area, at lower idle (no wake zone), in and out of gear (forward and reverse). In the past, used to have an occasional rattle at start up, at low idle, but always went away at higher idle.

How to distinguish between normal rattle and failing/failed damper plate? Thoughts?

Thanks in advance

'26 Pursuit CC
Crusader 350HP 454
 
Could be damper, but just as likely to be a bit of engine low speed roughness. Ignition service in the last 2 years?
 
I had the exact same issue when my boat was surveyed. The note said "will need damper springs soon". Once I tore into it, I had a burned cap/wire on the same engine. It's never made the noise since. I've posted this before but I think a very high percentage of Velvet drive knocking turns out to have nothing to do with the transmission.

There are some legendary posts worth reading...
 
hgput - you answered you own question. The rattle in or out of gear is usually a miss. The in-gear rattle, especially one that dissipates with increased RPM, is the damper spring indicator.
 
Thanks everyone. You know as I was thinking about it this morning, she was running rough, and I did notice mis-fires around 1,000 RPM. Time for cap, rotor, plugs, wires?
 
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