Oil leak out propellar - unburnt 2 stroke but running smooth?

muncedog

Seaman
Joined
Nov 13, 2014
Messages
67
Hi all,

On my 2000 oceanpro 130hp-

So I recently changed gear oil so was concerned to see an oil patch (thick dark oil trickle not residue) out the propellar exhaust after running on muffs.
I'm almost certain it's not gear oil, it's black and not smelly. The motor is running sweet from cold, not smoking excessively etc, so it seems odd that excessive 2 stroke oil might be coming through, surely it would run rough?

Any thoughts? Each time I run for a few mins there is a good 50ml at least dripping out!

If it's a gas restriction or air leak, again wouldn't it run rough? No alarms, automatic choke drops rpm back when warm etc.
 

racerone

Supreme Mariner
Joined
Dec 28, 2013
Messages
23,496
It is the nature of your motor running on muffs.-----On a PERFECTLY tuned motor like yours there is fuel and oil pumped through the motor.----This fuel / oil is lost without being used / or compressed and burned to produce power.----Difficult for some to understand I believe.
 

muncedog

Seaman
Joined
Nov 13, 2014
Messages
67
Hi all , thanks for the replies, just odd that I never noticed this after 5 years of owning the boat. That said, motor is normally trimmed up enough so it wouldn't drip out by the propeller. Just to confirm, this is not residue but as thick as the oil goes in- presumably gas has long evaporated!

Certainly no leaks under the hood, can a vro leak in such a way that it would continue to seep through long after shutting off as it appears to?

Thanks
 

flyingscott

Admiral
Joined
Apr 8, 2014
Messages
6,371
On a carbed 2 strk you do not have complete combustion. That means some fuel oil mix is pushed out of the cylinder and goes out with the exhaust. When the engine gets up to operating temps combustion becomes more complete, and less fuel oil mix is exhausted. It is worse when you run on muffs because there is no exhaust back pressure, and the motor never reaches operating temp.
 

FyshHunter

Cadet
Joined
Oct 8, 2019
Messages
12
Had the same issue, thanks for putting my mind at ease. Not experienced it with other outboards but then this one has been purely running on muffs while I sort out my overheating problem (waterways caked with salt buildup and worn water pump)
 

oldboat1

Fleet Admiral
Joined
Apr 3, 2002
Messages
8,295
Had pretty good flushing success with salt away when running in salt water. The converging ring on the prop hub will help draw away some of the unburned fuel that might otherwise stay in the hub and drip on your driveway. You can buy a replacement if yours is missing.
 

iggyw1

Senior Chief Petty Officer
Joined
Oct 24, 2011
Messages
771
I have the same problem with my kicker motor when the lake water is cold. The warmer the water is, the better the motor heats up to operating temperature, and the less oil dripping beneath my motor in a full down position.
 
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