A unique website dedicated to fishing information from Florida's Northern Big Bend. This includes the area from the Econfina River west to the Apalachicola River
Hopefully, I will have a picture show up with this post.
Does anyone know where this oil is coming from? Or better yet, what does it mean? It is coming from the area of a bolt (which you hopefully can see in the picture). None of the other bolts have any oil coming from them. I cannot see anything from the top when I take the cover off. I wipe this off before I go fishing, and then do not see much once I get home, but days later I see this. The motor is a 1998 25HP Yahama. It showed up about a month ago.
I would suspect gas is leaking from under the cowling, or coming out of the carbs, and is washing all of the goo out of the bottom of your cowling. I've seen the same thing on my motor.
If you have fuel leaking from carb, the engine should run rough, since too much fuel makes it run too rich. You could check to see if you can detect fuel leaking while engine is running. If your photo is the result of fuel leaking from carb caused by a blocked needle float that is not sealing off the gas flow into the carb when the carb fills up, here's what I did to fix that on a 1998 Yamaha 200: Took off air cleaner to expose carbs. Each carb has a small metal tube going straight up. This leads down into the fuel bowl where float is. My step-father and I took a small plastic tube and placed over the metal tube and sprayed choke/carb cleaner into carb. Sprayed enough to fill up carb. Let it set overnight. Drained, then sprayed again and immediately drained. This cleaned out the gum, varnish, etc. from the carbs, including the float valve that was blocked.
If you leave your fuel line hooked up, pressure build up in the tank from sunlight or heat can push gas/oil out and it will generally take the path of least resistance. Nothing major.
One other possibility is that two cycle oil is leaking from the tank around a rubber cap about half way up the side of the tank. I had this problem with my 97 Yammy, and fixed it by placing a zip tie around the cap to tighten up the seal. I'm not sure what the cap is for but I believe it is for a low oil sensor or something. Should be easy enough to check for that problem. Just see if you have two cycle running down the outside of the tank.