Originally Posted by Downhilldai
If you do a search on here, you'll find some horror stories of these motors suffering corrosion in the waterway around the joint between the powerhead and water tube/mid section. IIRC, the metal casting is very thin and corrosion can cause it to disintegrate, requiring a replacement cylinder block.
Other than that, I believe they're pretty rock solid.
AFAIK it was some of the early 90 4str engines with carbs that had that problem - around year 2000 (which is the age of mine
) It was caused by a poor choice of metal for the adapter plate that allowed the Yamaha engine to be connected to the Mercury leg. I think they've fixed it.
I think the 2005 engines are not Yamaha based, are fuel injected, and I don't think anyone's moaned on here about them. Mine's a different engine, so that's why I said nowt.
Notwithstanding my recent electrical problem (which is the first failure I've had), my engine has been reliable. It seems well made and fairly easy to work on.