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2005 mercury 40hp 2 stroke 3 cylinder

birkdallas

New member
Okay so i have an issue yesterday my boat motor locked up on me while I was out on the water. I could turn it by hand for for about one and a 1/2 rotations, and then it's like it's locked up at that point, but you can turn it back the other direction. And for the same amount of rotations, and then you hit the same issue, you hit something hard. I just want to make this part. It's clear. I did check the 2 stroke oil and it. Looks like it has barely went down after 15 times of being on the water. So i'm assuming that it's not get enough oil, and this is why it's locked up in a sense. Also, when I got home yesterday, I took out the spark plugs and put atf and penetrating oil in all of the three cylinders. I waited 24 hours 1 outside and was able to break the motor free of whatever it was catching on.
I did not force it and It was easy But there's still a catch/clunk when it turns over. I should add when I got home yesterday. I'm going to take the spark plugs out. I spun the motor the little that it could and no water came out of the plugs. From what I can see without a borescope The pistons look fine now, like I said, that's without borescope.

Things to remember all 3 cylinders, we're moving freely. No water came out of the cylinders.When I took out the spark plugs. The motor is now currently freed. Still has a catch/clonk when trying to turn over the motor. Lack of oil being added to the fuel
More than likely cause this issue.


So first question what's making the motor act like it's locked up, but all three cylinders can move freely.

Second question, what would make the two stroke oil Not mixed with the gas properly.

Third question, can anyone send me pictures or post pictures Of their 40 horsepower Mercury the side where the throttle is and shift linkage hooks up and your set screws location it would be greatly appreciated!
 
Remove lower unit and see if it helps.----But it does sound like a rebuild ( $$$$ ) is in your future.-----Or perhaps another motor.
 
Honestly I got to looking at prices for the parts and I'm just going to find me another motor. I would like to one day rebuild it but when I can find motors on Facebook marketplace for under $500 working/ running/ holding good compression then why not go that route. Im a big fan of saving time and money. And every day I'm not fishing is another day closer to the Ole nut house 🤣
 
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