'69 Merc 75 (7.5 HP) PISTON SCORING

saltyfries

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May 11, 2009
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Just looked through the transfer port of my 1969 Merc 75 (7.5 HP) and found scoring on the bottom of each cylinder. Up near the rings they look good as the pictures show. Compression checks good. What do I do about this? Pictures show upper cylinder, bottom is similar.

Thanks
 

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Laddies

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Re: '69 Merc 75 (7.5 HP) PISTON SCORING

That looks as if the engine may have lost the water pump in the past causing the scoring. If you don't get piston slapping when cold and it idles OK don't worry about it as if the parts are available it still would be a expencive fix.
 

saltyfries

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Joined
May 11, 2009
Messages
27
Re: '69 Merc 75 (7.5 HP) PISTON SCORING

That is consistent with the heat damage I found on the water pump housing. Actually, it doesn't idle very well but I think that could be because of the worn points. I didn't hear any slapping sounds. Let's just say, worst case senario, that I have no choice but to repair it. What would I have to replace? Or, would it better to just part it out?
 
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