I have a
Yanmar 2YM15 (350 hours) coupled to a
gearbox with 2.62 reduction ratio both purchased new in 2015 which is very noisy when running ahead but does not make any
noise when going astern. I have a 2 bladed folding right handed prop and the prop shaft is rotating clockwise in forward
gear when viewed from astern as per the
Yanmar manual. The
noise when in forward
gear is a very loud whine that increases with increased revs. This noise does not occur when going astern. I am now advised by the Yanmar agent that I require a new
gearbox but I am inclined to think that there may be some other problem or other way to resolve this. The problem has been present since installed new but agent at that time disputed that there was a problem. Is anybody able to throw some light onto why this may be occurring?