73 6hp Seahorse Issues

Yoby

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I was out on the Red about a month ago now and dropped my jon boat in with my 6hp seahorse(johnson). I had started it up and for whatever reason it wouldn't rev up quite right. I dicked with the lean/rich and little change. Well at the end of the night I had ended up breaking the pull rope. I had looked at it again until last night.

Thinking I was going to need to go through the carbs (even though I had done that last year), I started simple with the spark plugs. The first plug indicated that I was running heavy on the mixture (oily look), the other plug (bottom) was completely different. When I pulled it, there is no way it was sparking right. It was completely covered in a milky dark gel. It reminded me almost of axle grease. My only assumption is that there is water getting in some how (have only seen that when water and oil mix). Don't know if it was from condensation from sitting over winter, bad fuel, or I have a gasket leak. I am going to do a compression test tonight to see if its a gasket.
 


Yoby

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To be quite honest, I didn't check for spark.
 

Yoby

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Got home and started digging. Checked the spark, yep got spark. Pulled out the compression tester. 1st cylinder (the one that wasn't milky) 90psi. Checked the second 0.... what, checked the first again 90. Checked the second, 0... Checked it again by making sure the oring is set, 0. So I tore the head off. Sure shit, missing a piece of the gasketing. The picture below shows it. Bottom cyclinder on the right side. There is a chunk of gasketing missing.

20150518_205903.jpg
 

Davey Crockett

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Without knowing details or seeing the motor my first guess would be the bottom seal is out on the power head . It's the bottom cylinder ? And does the motor sit low in the water ?
 
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Yoby

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Without knowing details or seeing the motor my first guess would be the bottom seal is out on the power head . It's the bottom cylinder ? And does the motor sit low in the water ?

So I have read this a couple times now in a couple different places. What do you mean by it sits too low in the water? The back of my jon boat is short so I have a short shaft. I know it still sits low, but didn't know that the motor can sit too low. What is too low vs too high?

I was able to get a new gasket on it last night. Check the compression. Both cylinders now are in the 90s.
 

Davey Crockett

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You mentioned bottom plug being milky looking like water and oil mix, I had an old 85 HP mercury that did the same thing on the bottom cylinder , The crankshaft seal on the motor was in bad shape and water would get in the bottom of the motor. I ran mine that way and never did anything with it but it was always in the back of my mind. A buddy whittled it out of me for a tractor , I told him about it and he was still running it many years later, It might still be going .

- - - Updated - - -

I'd slap it together and run it.
 

eyexer

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you fixed your problem. coolant water was mixing in the cylinder with the oil/gas and making it milky. new gasket solved the issue:;:thumbsup
 

Yoby

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Took it out over the weekend. Yep, problem solved. Idled nice and ran great.
 

svnmag

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Would it not be more logical to measure aquatic engines in seahorse power(shp)?
 


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