gray-brown sludge leaking

[claytonr]

All,<br />First of all I appreciate ya'll taking the time to read my post. I have a 2002 9.9 Merc and just took my boat out after a long winter storage. I started the motor up and let it idle for about 5 minutes. After I did this I put my 2 year old daughter in the boat and idled around the marina for about 20 minutes. After doing this I put the boat back on the trailer and ran it out of gas. When I pulled the boat out of the water, I noticed a gray-brown sludge leaking out of the prop. Is this from idling for an extended period of time or from water leaking into the lower unit?

 

[WillyBWright]

Re: gray-brown sludge leaking

Unburned fuel that condensed in the exhaust. Had you run the motor faster, it would've blown that into the water. They run horribly inefficiently around idle. A lot of the fuel goes right past the cylinder and out the exhaust. At higher RPMs, the efficiency improves a lot. If the water is cold, that increases the condensation.

 

[claytonr]

Re: gray-brown sludge leaking

The water was pretty cold. So I'm guessing that you guys don't think that their is anything wrong with my motor?

 

[dajohnson53]

Re: gray-brown sludge leaking

The exhaust has a lot of unburned oil/fuel mixture in it, especially at idle. The exhaust comes out of the prop area. As WBW said, it's just condensed oily residue. The alternative would be that it's somehow leaking gear oil (unlikely) - but you can tell the difference pretty easily by smell. The gear oil has that....gear oil smell . But in my experience the messy crap around the prop is always exhaust sludge.