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1984 (?) Mercury 90hp 6 inline 2 stroke or 4? s/n: 6571408

rwernst

New member
Looking at a used boat with this motor

1984 (?) Mercury 90hp 6 inline 2 stroke or 4? s/n: 6571408

Info gotten from the serial number. I don't see any plates with the letters for shaft length (it's a 20" shaft), etc. just those numbers on plate on the transom mount (right rear), or starboard/aft... :)

They say it's a 4 stroke, but year and tower of power indicates it's a 2 stroke. They started it up, but who knows if they actually added oil to gas or not, they don't seem very boat/engine knowledgeable.

Can't seem to find any specs, but what I do find indicates it's 2stroke, except one thing that says there's an autoblend part.

Thanks for any links/help.

Oh, looked for an oil tank, couldn't find one, nor could we find a dipstick to check the oil, nor place to put oil in if a 4 stroke.P1060717 mercury 90hp outboard serial number 20.jpg
 
That would be a 2 stroke engine.----May have an oil injection system.----Some folks think that if you don't have to mix gas / oil it must be a 4 stroke engine.----Buyer beware here.
 
Sorry----I think those motors used the " autoblend " unit -.A separate tank inside the boat.------No oil tank inside the cowling !--------Those autoblend units should be heaved on the landfill pile.
 
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