Two Stroke Oil Accumulation in Intake Manifold.

[HerbieJ]

I recently bought a used 1994, 60 HP, 3 cylinder, oil injected, two stroke. It's been on a stand since I got it. I started to rebuild the carbs today and discovered that the green two stroke oil leaking from motor was coming from the lowest of the three carbs. When I pulled the carbs, I saw it was actually coming from/through the lowest two reed valves behind that carb. I pushed the reed valve open with a screwdriver and the oil gushed out - about 3/4 cup! How in the world did it get in there??? It didn't come through the lowest carb: I opened that up and found no oil inside. The oil appeared to be clean and wasn't diluted by gasoline. This is a typical Mercury oil injection system: oil injected into fuel line before the fuel pump, then sent through the fuel filter to the top carb, then gravity fed to Carbs # 2+3. Hope someone out there recognizes this problem and can tell me what is going on. I'm also hoping for a suggestion or two for correcting the problem.

 

[Texasmark]

Re: Two Stroke Oil Accumulation in Intake Manifold.

SWAG: The engine has an engine mounted oil tank, right? You had the engine tilted up.

You had the oil tank at least 3/4 full, right? You have a leaking seal on the filler cap to the oil tank!!!!!! BTDT I replaced the cap assy (didn't sell the seal alone) and ceased to fill my tank any fuller than a little less than 3/4......I set the max fill level so that oil is just below the seal on the opening with the engine tilted up. Have had no problems since.

Mark

 

[HerbieJ]

Re: Two Stroke Oil Accumulation in Intake Manifold.

Thanks Mark. The leaking occurred with the engine stored vertical. The filler cap seal appears to be in good shape, but I'll do some testing on it.

Herb

 

[sschefer]

Re: Two Stroke Oil Accumulation in Intake Manifold.

Possibly -
1.Bad check valve on the lower/upper mains.
2. Broken/worn crank sealing ring(s).
3. Stuck float on #3 carb.

A stuck float on any carb and item #2 will cause the same symptom.

 

[Texasmark]

Re: Two Stroke Oil Accumulation in Intake Manifold.

SWAG: The engine has an engine mounted oil tank, right? You had the engine tilted up.

You had the oil tank at least 3/4 full, right? You have a leaking seal on the filler cap to the oil tank!!!!!! BTDT I replaced the cap assy (didn't sell the seal alone) and ceased to fill my tank any fuller than a little less than 3/4......I set the max fill level so that oil is just below the seal on the opening with the engine tilted up. Have had no problems since.

Mark

Oh well, it sounded like a good theory.

Good luck.

Mark