Yanmar 2YM15 Oil leak Pattern- Need advice please

[circa1971la]

I need some advice about my Yanmar 2YM15

6 months ago I had the engine serviced by a very reputable company out of Newport Beach, California.

A few weeks later there was an oil drip in a unique square shape drip that seemed to be coming from the starboard side of the motor. The mechanic came back and checked it and said it was “residual oil on the engine that was not cleaned efficiently during the last service”. He cleaned the engine and start/ran the engine at slip and did not notate any further leaks or drips.

A few months later after a lot of motoring to Catalina it recurred. They came back again and cleaned the area of the fluid and ran the engine and transmission to temperature but were not able to source any leak. They said it was “probable residual oil on the gear case, it is very difficult to get residual oil off the gear case due to the material it is casted in.

Now again it has recurred after a long day of motoring. The oil level is still ok and it runs good but obviously this is not normal. I’ve attached photos and would really appreciate any suggestions.

View attachment 219517

 

[BigEasy]

Possibly leaking from valve cover gasket. Another thing to possibly check (if present) is an additional dip stick port on starboard crank case. It is a short metal stubb with a rubber seal. It can not only leak, but can blow out of the port & really cause a mess. I know there is one on the 3YM30.

 

[RoyS]

Square oil stain is usually caused by water mixed with oil. Water spreads the oil to the edge of the puddle.

 

[kloudie1]

Leak appears to be dripping from the top left of the picture then spreading according to heel, pitch, and whatever miniscule "unflatness" in the pan under engine. The way to find it is to put a pad under the engine and then when you find the drip, start looking upwards until you find the origin..

 

[danooxnard]

RoyS has a good point. Oil alone would not make a square pattern. Dano

 

[Rich Stidger]

My experience with drips of anything is that they can originate a long way from where they drop off the engine. +1 for @kloudie1 for his opinion and suggestion.