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- I’ve got a 2009 T60 Yamaha 4 stoke Outboard.. when idling and at low rpm motor sounds excellent but as soon as it hits 3-4000 rpm there’s a rattling noise coming from engine.. Doesn’t sound like a bearing as it’s not a knocking noise.. sounds like something is loose and rattling.. Anyone experienced this befor??
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Remove upper cowling and check throttle linkages and other plastic parts that can rattle at certain RPM’s…. -
could it be preignition?Comment
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It don’t seem to be plastic rattling.. what It sounds like is the aluminum plate on the front rattling but all seems good there.. The higher the rpm the noise gets louder.. could a bearing cause this sound? I always thought if it was a bearing you would get a knock.. I thought I new these engines pretty good as I’ve pretty much done it all with them.. but this rattle got me stumped and I wanted to see if anyone else experienced it befor tearing it down.. Thanks for the repliesComment
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I didn’t think about pre ignition.. but definitely can be it I guess.. I did notice that when I done a compression test after it was sitting all winter on an engine stand there was lots of gas in the cylinders.. But it fired right up no issues but did have a little knock at first but went away.. Idling sounds like new but after half throttle is rattles loud..Comment
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bore scope the cylinders to inspect the tops of pistons.
is there a lot of carbon?
look for mark on top of pistons to make sure there are no signs of the pistons hitting valves
check timing with timing light to make sure it is correct when you start hearing the noise
make sure cam timing is not off, I guess this motor has a belt
just some thoughtsComment
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