8hp Burnt oil at prop

Quad82

Seaman Apprentice
Joined
May 22, 2010
Messages
47
Hello
I have a 1986 Merc 8hp short shaft 2-stroke on my 16' Fisher. I just got the motor a couple weeks ago to replace my Johnson 4hp Delux kicker. After doing some maintenance on it (new plugs, new fuel lines, LU oil) I used it trolling for most of a day. It ran perfect, but the short shaft was still too short. Stock it is/was a tad longer than the Johnson. But not much. Had to sit in the back of the boat to keep it in the water without cavatation (sp). I had the 4hp on a adjustable kicker mount. But never liked it hanging off the back, or having to drop it, lift it ect.... So I mounted the Merc on the transom. Thus, the height problem. So I bought a 5" shaft extension from Bay Manafacturing. Fantastic product! A little pricy at $340. But it did exactly what I wanted it to. Now both my buddy and I can walk up front while trolling without a problem even in decent sized waves.

Before the extension upgrade and after running the motor for almost 14 hours, I parked it in the grass at our cabin. I didn't notice any oil on the LU. Didn't really look. I didn't have a transom saver on the kicker then. I useally do. But didn't get a chance to modify the one I used on the Johnson. So the LU was pointing down and all water was drained by the time I got home and parked it in the garage. So then I installed the extension and modified the transom saver to fit the longer leg. After running the motor for several hours, we left it tilted up when we pulled it up on the trailer. I dropped it down enough to set it in the transom saver and towed it home. Never thinking to drain it. Put it in the garage and lowered both motors off their transom savers. The next morning, there was a puddle of water that had run out of the LU with a dark, burnt oil stain in the middle. There was dark oil seeping out from behind the prop. I took the prop off and cleaned the burnt oil out of the housing. I then drained the LU oil. Full, no water and it looked as new as it did when I put it in 2 days ago. Ok, so much for the history. I did search. But only found 1 thread that said anything about unburnt mixed oil. Sorry it was sooooo long. Just wanted to cover all the info I had. Now the question...


Is this just unburnt/burnt mixed oil from the exhaust that collected in the exhaust tube/housing? Thanks. Darrell
 

Quad82

Seaman Apprentice
Joined
May 22, 2010
Messages
47
Re: 8hp Burnt oil at prop

Has any one seen this? Thinking it might be that I am trolling with it instead of running WOT and burning the carbon. Pretty sure it's just carbon or two-cycle oil. But am concerned.
 

mr 88

Commander
Joined
Nov 3, 2010
Messages
2,220
Re: 8hp Burnt oil at prop

Yes your last sentence in your first post is correct, most people leave the lake with the motor up,so it puddles there until you drop the engine when home.Type of oil and ratio along with carb setup can minimize the small mess or just be aware of it and throw a rag under it when in the down position. 50-1 and Pennzoil T-C 3 synthetic oil should do the trick.
 
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