40 HP Mariner 2 stroke keeps seizing

bmxjeff

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Jul 19, 2012
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I have a 40hp Mariner 2 stroke outboard. My problems started when I kept fouling plugs from idling for long periods of time.(I run at idle a lot through shallow creeks to get to my top fishing spots) Someone told me I was running too rich, therefore fouling the plugs. I adjusted the fuel/air mixture and got the motor running like a champ. I took her out on a test drive and everything seemed fine. I came back the next day and the engine was seized. I was able to put a wrench on the crankshaft and unseize it. After that I tried to run it again, it ran for maybe 10 secs and I noticed it wasn't firing on the top cylinder. I pulled the top cylinder plug and it was fouled. I then came back a couple days later to put a new plug in and the motor was seized... again. This time I can't free it. I poured marvel mystery oil into the plug holes and I am going to let it sit for a couple days and try again. Any one know why it would be seizing? I am mechanically inclined however I don't have much experience with outboards. Any help would be greatly appreciated. Here is all the info on the outboard

Mariner 40 hp Stroke, twin carb
Serial #6E9-409257
I am not sure of the year, I think its 86-89??
 
Joined
Apr 24, 2012
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18
Re: 40 HP Mariner 2 stroke keeps seizing

I am not a mechanic by any means, but my 1st impulse is to think you possibly leaned the engine out way too far and over-heated it just enough to expand the pistons to the point of slightly damaging the rings, so things aren't meshing very well within the cylinders anymore. Now, that is only a gut reaction to your situation, but I hope it helps a little if any.
 

bmxjeff

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Joined
Jul 19, 2012
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Re: 40 HP Mariner 2 stroke keeps seizing

Thanks fish fry. That's what I was thinking as well. I guess I was just hoping something a little easier to fix was the problem.
 
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