Black oil down my skeg

[TCW]

I have a question--I bought used a 1993 40hp Mariner, which I presume is a 4 stroke since I don't mix oil and gas. After use, I get a line of black oil down the skeg apparently from the exhaust/end of the propeller. I recently had all seals replaced and I do not get water mixed in my lower unit oil from usage. Is this anything to be concerned with, or just exhaust run-off? Any help is greatly appreciated!

 

[fastback4]

Re: Black oil down my skeg

You must know if your motor is 2 or 4 cycle. It's just good information to have. Is this your first watercraft maybe? Presuming it's a 4 cycle engine your oil down the skeg could be from a leaking lower unit grease fill port or a faulty valve seal allowing motor oil to escape past the valve seal into the exhaust manifold and down the skeg.......
Does this occur all the time? Are you sure it's oil? I've seen this happen after an engine has had the combustion chambers flushed. Pull your engine cover off and look to see any oil pooling. If there is pooling oil clean the area well and then run the engine to see where it's coming from.

 

[saumon]

Re: Black oil down my skeg

There's no such thing as a Mariner 1993 40hp 4-stroke. Yours is definitely a 2-stroke and, even if you don't premix, there should be a separate oil tank on the engine.

And yes, the black gunk can be unburned oil from the exhaust.

 

[fastback4]

Re: Black oil down my skeg

There's no such thing as a Mariner 1993 40hp 4-stroke. Yours is definitely a 2-stroke and, even if you don't premix, there should be a separate oil tank on the engine.

And yes, the black gunk can be unburned oil from the exhaust.

Thanks Saumon...Was not certain when 4 strokers came around.......Tom