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90 mercury rattle only when shutting off

R

Rnewmans

New member
So I just purchased an 07 mako with a 90 Mercury. Motor seems to run fine with no issue. Except when I turn off the motor there is a rattle noise for just a moment. Sound like something is loose and when the motor turns off whatever is loose is no longer under load so it rattles as the motor comes to a complete stop. I’m a new boater and not sure what the rattle could be, if it’s just something loose or more serious or rather it’s safe to be out on the boat. Any assistance would be greatly appreciated.
Rob
 
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Sound like something is loose and when the motor turns off whatever is loose is no longer under load so it rattles as the motor comes to a complete stop.
 
Check flywheel.----Can you move it up and down at all ?----Check flywheel nut torque.----Or on the port side of the motor you will find an exhaust cover ( 20 bolts or so ) to remove.----You can then inspect pistons / rings / connecting rod play.-----2 new gaskets if everything in there is OK.
 
racerone said:
Check flywheel.----Can you move it up and down at all ?----Check flywheel nut torque.----Or on the port side of the motor you will find an exhaust cover ( 20 bolts or so ) to remove.----You can then inspect pistons / rings / connecting rod play.-----2 new gaskets if everything in there is OK.
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not at the boat currently but I’ll give that a try. Thanks.
 
If your shutting it off in gear you are hearing clutch dog ratchet from prop turning. If in neutral have seen the lower bearing inner race separator bad..balls keep spinning in race when shut off. Seen this several times
 
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