older Yamaha 20 hp noisey

dunkster

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Joined
Aug 20, 2013
Messages
3
motor runs fine but occasionally (usually at full or close to throttle and I hit a wave hard) it will suddenly get very loud. Water keeps pumping, and continues to run. If I back it off and slow right down it will go back to normal and I can open it back up again. If I compare it to a car I would describe the sound as a noisy muffler.
Any help appreciated
Thanks
 
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