Volvo Penta d2-75 oil leak

[SailingMed]

My brand new boat has a Volvo penta d2-75 engine. I have noticed that there is a very small oil leak from a breather hole below the turbo. I know for sure that there’s a breather hole there because I can feel the air (like blowing out of a straw) if I place my finger below it while the engine is running. But why there is also oil? Anybody came across similar problem?
Thanks

[DougR]

Your engine is turbocharged and aftercooled, and after coolers almost always have a small drain hole in the aftercooler housing to allow condensation to drain from the housing instead of going into the engine. Typically there is a small hole drilled, and then a roll pin is installed in the hole.

The reason is that the intake air is heated by the turbo compressor and then cooled back down somewhat by the aftercooler. This cooling causes moisture to condense on the fins and tubes of the aftercooler element, and then the moisture drops to the bottom of the housing.

It looks like oil because there is a bit of oil mixed with the water. The oil works its way past the turbo seals, particularly if the engine is run at low load for long periods of time. Low load means the turbo isn't working hard and there is no boost pressure in the inlet tract, but instead there is some slight vacuum present. This vacuum pulls oil past the seals. If you run the engine harder so that some boost pressure develops the amount of oil should be lessened.

[SailingMed]

The engine maximum rpm is 2800 and I run the engine usually at 2000-2100. Is this considered adequate? Occasionally I will run it at 2500 but only for a few minutes.

[Neptune's Gear]

Rated revs is 3000, not 2800. 2700 is a suitable cruise speed, an 2000 will have basically no turbo boost....

Run it too slow and it will carbon up the turbo. 2500 is ok, but 2700 for 30 mins every now and again is good for it.

If it only pulls 2800 at WOT, its over propped. That's bad. Volvo warranties require an engine to be able to reach max revs (in this case 3000)

[Clint09]

I had the same problem from new with the same engine in a Hanse 505. It covered the transmission with oil and accumulated in the tray below the engine. Also factor in that the crank case breather feeds in to the inlet manifold and this is a source of oil mist. I lowered the oil level in the sump to about halfway on the dipstick and I think this helped the problem. The other thing I did was get football inflater needle with a piece of plastic hose inserted into a small orange juice bottle. The bottle cap had an 8mm breather hole. This was an effective oil catch tank. The needle fitted perfectly into the breather hole and it was secured with stainless wire.
Just don’t let the needle touch the intercooler internal tubes. Cut the needle to correct length. We used this for maybe 1200 hours.
Good luck.