2012 Tohatsu MFS20C - Losing Oil

[team Lott]

Need some help. This motor I bought used and runs great but using a lot of oil. It is progressively getting worse. I cannot find a leak but there is a heavy residue inside the cowling around the carb breather. Again, the engine runs so good that I cannot imagine the rings are by-passing. I looked at the crankcase breather tubes and nothing is stopped up. I'm thinking that maybe the fuel pump and getting a draw of oil from it during fast acceleration. It is consuming or leaking nearly a quart about every 3 hours of run time.

Anyone have experience with this motor and similar issue?
Thanks
TeamLott

 

[MattFL]

Is there any smoke out the exhaust, and how does the spark plug look? The compression rings and oil control rings are separate, it's not all that unusual to have a motor that runs well but the oil control rings are letting oil into the cylinder. With that much oil use, if it's leaking you're either going to have a heck of a puddle under the hood, or it's leaking under the powerhead and going out the exhaust. If you run it in a bucket or on the hose, do you get a lot of raw oil coming out the prop with the exhaust?

 

[team Lott]

Yes, I have some blue smoke but not consistently. No, I'm not seeing any significant oil coming from the exhaust. On my last outing, I added seafoam to the fuel. For the first time, I ran into a run ability issue and filed out the plugs. They did not appear to be oiled filed.....it was a maroon carbon like and dry burnt deposit on both the plugs. I cleaned them and it ran great again for about two hours and filed out again. The only change was adding the seafoam. It does appear to be getting worse. Will a compression test help determine an oil ring issue? It is the amount of consumption I'm having a hard time understanding.

 

[team Lott]

I plan to clean the engine and run it in a barrel. I forgot to mention that I did replace the oil pan to power head gasket. That did not make a difference. We see a small sheen of oil in the water after we stop, but never see a leak. Would it be possible for the fuel pump to be by-passing?

 

[pvanv]

Are you over full of oil at all?

 

[team Lott]

Are you over full of oil at all?

No, not at all. I have ran the motor until the low oil indicator came on. The engine has a fail safe mode for low oil as well. We check the oil before every outing now. It is definitely going somewhere. I wish it was a leak for me to see. As it stands now, my thinking is fuel pump by-passing the diaphragm or oil rings. I plan to run the cleaned-up motor in a barrel this weekend.

 

[pvanv]

If the fuel pump fails, it typically sends fuel into the crankcase. Not the other way around.