Old 2-Cycle Mercury Oil Leak

[l008com]

I had a post I started about this last year but I wanted to start fresh.
The motor is a 1989 Mercury 90HP outboard, 2-cycle 3-cylinder
For the last few years, it seems to have a slow oil leak. Slow enough that the tank isn't running low or anything, but fast enough that theres always oil everywhere. All over the cabling and wires towards the bottom of the motor, all over the splash well, all over my driveway.

It was suggested I clean everything then look and try to see where the oil was coming from. So I did clean with a spray bottle and dish soap. I got everything pretty clean, but alas, I couldn't see any oil dripping from anywhere.

Well today I started up the motor for the first time this year. Long story short, it took a lot of cranks - the motor is old. When I was done I got down in there to re-route the fuel line properly and oil was pouring out! For the first time, I actively saw it dripping, and dripping a lot. And it seemed to be coming from - not the tank, not any lines, but dripping right out of the air box.

So I took that cover off, a fun job when half the screws and bolts are fully soaked in oil, and oil or probably some level of fuel/oil mix, though it seemed thick, like it was mostly oil, was dripping out of all three carbs. By the time I got the cover off, it had slowed down a lot so the picture of it doesn't look too bad. But thats where the oil is coming from, and probably has been coming from for the past many years.

Now the motor has also been smokier than normal for the last few years. Methinks these problems are the same problem!

Here is video of it dripping:

And here is a photo of the intakes with the plastic cover removed:


So what do you make of this? This is not normal for this motor. Once you get it warmed up, the motor does run well as it has for decades. But it makes such a mess in the process.

 

[dingbat]

All the fuel in the carb bowls evaporated leaving bowls full of oil.

If it’s leaking at idle, your floats and or float valves need looked after

 

[l008com]

If its also smokier than normal at low speed, is that also an indicator that its the float valves?

 

[airshot]

Probably time to rebuild things like carbs and new fuel and oil hoses ! If your engine has been maintained, it isn't old, just needs freshened up a little. I have a 1992, looks and runs like new. As mentioned before, when the gas evaporates it leaves oil residue.

 

[Dave1027]

If the oil supply hoses have never been replaced I would start there. No doubt they have got to be toast by now.

 

[gbrowne63]

I just went through the same thing. I replaced all the lines rebuilt the carbs but i eliminated the oil injection because the motor was new to me and it is 40 odd years old. Same motor 1989 90HP. IT runs great so far.

 

[l008com]

Ok so I'm thinking I might take the carbs off and try to rebuild them myself, but this also really feels like a Winter project.
In the meantime, I went for my first ride today and it took a LONG time to get the motor running. It would die at low RPMs. So I could start it with a little throttle but it would die when I pulled it back to idle to try to put it in gear. But EVENTUALLY I was able to get it to the point where it could idle so I could finally put it in gear and give it some gas so I could actually drive it. Once I was going, I was able to drive it hard in a few spots and really get the engine behaving much better. But of course thats temporary if fuel and oil are leaking into my bowls, giving me a too-high gas oil mix.

SO WHEN I was done and at the dock, fighting with the stiff breeze :/, what I did was disconnect the fuel line at the motor and let the engine idle until it ran out of gas.

Is this a good method to get me through the summer without making too much more of a mess of things? I should be draining the bowls when I do this, right? So on next start, it should be fresh gas and a good fuel oil mix and the engine should start up a lot easier and run properly.

That's my thinking anyway, do you guys agree?