oily black fluid leaking from prop shaft...??

[MOTguy]

I own a 1996 200hp Evinrude Ocean Pro. I recently flushed the engine for several minutes following a day of boating. The next morning I noticed a very small amount of oily black fluid that had leaked out of the propshaft and down the skeg. I don't think it was gear lube as the lube was just changed and would look more like honey. What is this fluid ? Is this unburnt oil or gas? Is this normal? Thanks in advance for the replies.

 

[12Footer]

Re: oily black fluid leaking from prop shaft...??

By your decription of it's color, I think you are right, it's unburnt fuel. But I would make sure by checking the condition of the lube...Even after one trip,and especially if it was just changed.<br />A vent/fill screw gasket could be leaking,<br />the propshaft seal could be failing, and now is the time to inspect it. If the goo were comming from any other spot than the propshaft,I wouldn't be as concerned.<br />A cheap,semi-clean way to check the lube,is<br />with a pipecleaner. Get a new screw gasket<br />(cheap, about 5 for 2buks).<br />Remove the vent screw,and run the pipecleaner<br />into the vent hole (like an oil dipstick).

 

[MOTguy]

Re: oily black fluid leaking from prop shaft...??

Thanks for the reply. I should have mentioned that I did also replace the propshaft seals before I changed the gear lube. I too originally thought the seals were failing. I'm fairly certain now that it is unburnt fuel that is leaking. It's only a very small amount that leaks from the propshaft area. What is the remedy for this unburnt fuel? Could I be using the wrong spark plugs?

 

[12Footer]

Re: oily black fluid leaking from prop shaft...??

Actually, it's a good sign. It indicates your engine is getting ample lubrication.<br />It's burning too rich,but that is better than burning too lean.