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What year is this one Graham

A

atilla_boy

Regular Contributor
thanks graham and I found the

thanks graham and I found the numbers they are A115542. these are the ones on the aluminum plate thats riveted to the part that attaches to the hull. sorry not to fimilar with the OB motor terminoligy nor can i spell today. anywho what do these numbers tell me ????
 
"Yes, John, that's the ser

"Yes, John, that's the serial. Makes this a 1985 Merc.

You have one the many motors produced during a major change over at Merc.

The alphanumeric serials 0Axxxx etc were put in place for the new 86 models. In most cases the 86's were drastically different than the 85's as many significant changes were made. So the mid/late 85's can be almost anything.

If this 75 is a 4 cylinder, then it is the old design. If it's a 3 cylinder it the new design that continued unchanged until about 1994 - although I can't remember right off when they stopped producing the 75, but it was essentially the same motor as the 90 horse (and the 70 and 80 for that matter).

Aside from the production year, that number tells nothing at all. Hoever, that serial plus the number of cylinders will allow for determining which "parts list" applies to this motor..."
 
ok its a 4 cyclinder and it ha

ok its a 4 cyclinder and it has a problem lacking power. it hard for me to undersand cause it only has a speedo and nothing else. I changed the plugs and took it for a ride the boat with me and my dad reaches between 38 and 40 mph then all of a sudden it losses power and wont even do 30mph. so i pull the pluggs and there is a chunck of something on the 3rd cyc. down from the top. i cleaned it off and took it for a test run again seems ok now but not sure how long. its done this a few times but I think that cyclinder is the only one doing it what so I look for first. I can't tell if maybe that cyc. is burning lean and maybe its a chunk of the piston? can't tell though cause it covered in what looks like carbon??? damn 2 strokes
 
"John, could well be a massive

"John, could well be a massive build-up of carbon and other crud.

Stop by a Merc dealer and pick up a can of "Powertune" (about 5 bucks for a spray can) and just follow the directions on the can - cleans all the "cooties" out.

If you do give it a try and you get stuff that looks like spilled McDonalds chocolate milkshake coming out of the exhaust, you know it did it's job
Might make a world of difference. I use the stuff when I bring motors out of storage and have found it to work well..."
 
ok as soon as I get some I&#39

ok as soon as I get some I'll take a pick of it while doing it to see if this is what your talkingabout and thankyou much sir...
 
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