Mercury 2004 40hp, water in piston/cam shaft, why does this occur? Seems a common issue with this earlier model?

[SpearTub]

Im looking at a boat "as is shape". I know its getting water in the piston. I have seen a picture at the bottom of a cam shaft due to this issue and was all discoloured.

I do not know much more. But any guesses as to why this occurs? and what needs doing to fix it?

I saw it in a fishing forum once and the engine tech showed a picture of the bottom of the cam via a micro cam thingy and the walls were all discoloured.

I hope Im making sense as I do not know much about the issue and was hoping it might spark some knowledge on here about what occurs etc?

From what I read ages ago, it happened a lot in these earlier 30-40hp 2st mercs around 2004 onward

 

[racerone]

???----A cam ?----Then you indicate 2 st -----Pictures or a serial #

 

[SpearTub]

???----A cam ?----Then you indicate 2 st -----Pictures or a serial #

No, seller is far away from the boat, little frustrating.

Common issue though, if just googling it. Ive seen it before. Yes 2st, most small boats here still sell with 2 strokes. But this is a 2004 Merc 40hp 3cyl 2 stroke.

It might end up being purchase as is, if so I want the hull for less than its worth new, they quite rare but if the Eng has serious rebuild costs then the price needs to take that into consideration. Just thought somebody on here would have come across it before and might have had an idea of the fix. Otherwise Im valuing the engine as nil and unlikely will go any further.

Really hot market where I am, the largest city, is in covid lockdown, so boat prices are hyper inflated.