PHP Warning: Use of undefined constant VBA_SCRIPT - assumed 'VBA_SCRIPT' (this will throw an Error in a future version of PHP) in ..../includes/functions_navigation.php(802) : eval()'d code on line 1 Noise in Merc. 40 2 stroke
Hey guys, I test ran a 4.5m tinny on the weekend, it performed really well and is pretty much what I am after as a 2nd boat. I do however have a slight concern with a noise the motor was making when we were on the plane. It was not so much a knocking noise, as a rattle, and it seemed to come from the lower part of the motor. It only was evident at @ 4500 rpm, a couple of hundred rpm above or below and it went away.
Its pretty hard to pinpoint exactly where the noise was coming from skooting along at 20+ knots, but it didn't seem to be coming from under the cowl. It sounds fine at idle, full revs, etc..
Maybe I am being a bit paranoid, and tinnies definitely seem to amplify noises. Another possibility is the hydrofoil fitted to it was causing it. The motor did seem to be a fraction low, with the foil just under water at planing speed.
Has anyone heard something similar?? The boat and motor is a 2006 4.5m centre console /Merc. 40 3 cylinder with trim/tilt etc.
Maybe bottom crank bearing, parhaps bottom crank seal allowing a little water in.
Worth checking plugs for slight water beading after a run or maybe very small looking rust spots on the tip of the plugs will be a sign of a knackered seal.
It does have a SS prop, so maybe you have something there. I have to say the noise is more like a resonating sound rather than a rattle or knock, maybe a bit like really high pressure water hitting something or even flapping noise at really high speed, sort of like the "cardboard on bike spokes" thing as kids...
as I said after being used to 4 strokes on glass boats in the last few years maybe I am being paranoid , but I think I will get it checked before purchase.
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