Is this normal?

[Jefro573]

I noticed the substance that appears to come from that hole to the right above the prop when I pulled my boat out tonight to start it up. (see attached photo) I ran it last night on the hose for a while (20 mins). I rubbed my finger in it and its mainly oil I believe...dark brown if not black in color. Is this just oil leftovers from exhaust and is it anything to be worried about? I have been running it on a hose a lot lately while doing various repairs etc. getting ready for the water over the past month or so. Prior to that it was sitting in my garage only being ran a few times in the past 18 months or so. Any thoughts/ideas would be greatly appreciated.

 

[Jefro573]

Sorry, I have a 1998 Force 120 HP.

 

[Jiggz]

If you've been idling the engine for awhile, this is normal. At idle speed, unburned fuels do not get recirc through the fuel recovery system hence get carried over to the exhaust down the motor legs. Keep an eye on it and make sure it does not continue to do so after you ran the motor at high speed. If it does you might want to check the fuel recovery system to make sure it is not clogged.

 

[Frank Acampora]

What you are seeing is the reason why older design 2 stroke engines (your Force) are banned from many lakes. They simply do not fully burn all of the oil in a 50 to 1 mix and this oil goes into the water.

Since you are not running the engine in the water you are not cleaning the leg and you are seeing the unburned oil exiting a vent hole in the leg. I would bet that if you held your hand near the prop exhaust, it would rapidly be coated with the same oil.

 

[Jefro573]

Ok that all makes sense. I was thinking/hoping its because I haven't ran it at high speeds lately. After I run it in the water a few times I will see if I still see it. If I do then I will check out the fuel recovery. And yes I do believe I've seen that out of the exhaust by the prop before. Just not that hole.

Thanks for the help you two.

 

[Frank Acampora]

You may still see some oil exiting that hole even after running in the water. If you were to remove the lower unit you would see that in the front of the leg there is a blind cavity. The hole is purposely put there to drain water out of this cavity and avoid corrosion from it--especially if salt water were left standing in the cavity. This cavity is also open to the exhaust stream, therefore some unburned oil will always get into it.

Contrary, while it is a Brunswick Mercury designed lower unit and uses Mercury parts, Branded Mercs. have a specific exhaust down-tube with a gasket sealing it to the lower unit. Exhaust can only pass through the prop.