Oil from prop/lower unit area 2003 9.9 merc

[MFG197]

I have a 2003 9.9 merc and had a 15 carb installed and tuned by dealer. when you use the motor then bring it home there will be a small puddle of fairly thick oily substance on the ground the next day. gear lube looks ok and is full. should there be that much unburned oil in the exhaust system that it drips out? the oil also comes from a small hole just above the cavitation plate and behind the prop. I had a 1990 9.9 merc (almost identical) and never saw that.

 

[The Marine Doctor]

Re: Oil from prop/lower unit area 2003 9.9 merc

The engine is running rich.<br /><br />Are you trolling quite a bit?<br /><br />Also...I think the reeds are different with the 9.9hp vs the 15hp.<br /><br />TMD

 

[andrewkafp]

Re: Oil from prop/lower unit area 2003 9.9 merc

And running rich can increase carbon build up. Whereas running too lean can cause pistons/cylinders to burn. So you may have to adjust the Air/Fuel mix.<br />But try running it for long periods at good RPM's as it may only be temporary due to trolling.