Exhaust smelling oil from prop

[1canvas]

I have a 25hp merc 2001 2 cycle and I have for years seen seepage of brown oil looking substance from the prop from time to time. I change the lower unit oil at the beginning of the season and the end and never seen water contamination in the oil. The brown oily substance smells like exhaust so I suspect it's coming from the carb but not really sure how this is happening. The motor has always started easy and ran great. Any help would be appreciated.

 

[Alumarine]

The exhaust comes out of the prop hub when above idle.
What you're probably seeing is unburned oil from your fuel/oil mix. It's normal.

 

[1canvas]

The exhaust comes out of the prop hub when above idle.
What you're probably seeing is unburned oil from your fuel/oil mix. It's normal.

I was thinking it was something like that but I don't see that on any boats that come into my boat canvas shop. I wonder if my carb adjustments may be out of whack.

 

[1canvas]

I am thinking of selling this boat and that doesn't look good. If it wasn't for that I wouldn't worry because the motor has run great ever since I bought it new.

 

[littlerayray]

The exhaust comes out of the prop hub when above idle.
What you're probably seeing is unburned oil from your fuel/oil mix. It's normal.

+1 on that

 

[60sboater]

Maybe it's running too much oil for amount of gas. Is it oil injected or pre mix?

 

[1canvas]

Premix.

 

[Alumarine]

What are you mixing it at? It should be 50:1.
You could try synthetic oil if the residue bothers you. Sometimes they burn cleaner.

 

[Bill kubiak]

If your gonna sell it, clean it up before you show it, and do not offer demo rides, because they are BS, most buyers that want a demo will almost always say, Thanks, I'll let you know, you gave them a day on the water and you never hear from them again

 

[1canvas]

Ok, what I found was the choke nob was turned a bit choking the motor. I thought the choke nob could only be pulled in or out. It must have gotten turned while putting the cover on and off. I had changed and measured the lower unit oil to assure myself there was no issue there. I put the motor into a tank and adjusted the carb with the motor running in gear. The manual said to turn the screw in until the motor started cutting out from lean and turn out one to one and a quarter turn. I did that and the motor started chugging a bit so I set it at 1/2 turn out from lean. I then took it to the lake and it ran great at low rpm and high. I had no hesitation when accelerating. I ran it at top speed for about five minutes then back down to idle speed for 20 minutes. Everything seems great and the motor didn't load up at idle speed. There is no gas/oil present now from the lower unit/ prop area. Tomorrow I will change out the plugs and I might turn the mixture screw out 1/4 more turn and see what happens.