2012 DF140 gaining level in oil

[Alaskagunslinger]

My sons 2012 DF140 is gaining oil, about 2 quarts after running steady for about 20 - 25 hrs. Has anyone had this problem and what was fix?

A little background we hunt the Yukon River and run about 500 miles downriver from the launch to where we hunt it is usually in two days averaging + 30 mph at 4,500 - 5,000 rpm, boats are loaded (mainly fuel) but his 20' SeaArk is not that heavy and has to throttle back as I lead on the trip.

This problem was first noticed in 2018 and local dealer changed out fuel pressure regulator and a stem and seat, 2019 trip the problem continued, so after discussions with dealer it was decided to monitor oil closely on the next trip 2020 and see if the problem continued, which it did.
It is definitely gas as you can smell it and oil is still pristine ****en color and no emulsion so water has been ruled out.
We drain the oil down about 4 quarts and fill back to dot on the dip stick on the trip for the run back to launch, and change the oil/filter when we get home.
He bought the boat and motor used, motor is a 2012 but was purchased from the dealer new in 2015 so warranty was good into 2020, now 2021 that is another issue but I will deal with that later.
Any ideas or thoughts. would be greatly appreciated

[Moonlighter]

Been a few similar reports here over the years.

VST has a vent hose that runs into the crank case (due to EPA rules about releasing fumes to the atmosphere) and if the float level in VST is set wrong or its clogged in there, needle stick etc, then raw fuel will run out of the vent tube into the crank case. And thus it gets into the engine oil.

Can check if this is the case by starting the engine with the cowl off, pull the vent hose out of the connection to the crank case and watch it for some time, if fuel drips out you have found the issue and can then fix it.

[Alaskagunslinger]

Passed on to the dealer mechanic thank you

[Murray]

Does the low pressure fuel pump have the potential to leak fuel into the crankcase?

[redlowrey]

Does the low pressure fuel pump have the potential to leak fuel into the crankcase?

There are two possibly three ways fuel can get into the engine holder of a df140 1 fuel overflowing from the vst 2 a ruptured diaphragm on the low pressure fuel pump 3 it is possible for fuel to get passed the rings into the engine holder, only if the ring gaps on the top and second ring, and the top oil expander ring had all the gaps lined up on the same side that the injector sprays fuel into the inlet manifold.

When the inlet valve opens just before tdc on over lapp, as the piston moves down the cylinder, any fuel that has condensed on the cylinder wall after being drawn into the cylinder, as the piston moves back up the cylinder on the compression stroke, fuel that has condensed on the cylinder wall will be pushed passed the piston with the ring gaps lined up will end up in the crank case.

[catacom225]

My 140 was making oil, replaced the low pressure fuel pump and it stopped. I removed it and pumped the primer bulb and saw it leaking. Also you could remove the vst overflow line next trip then see if it still makes oil

[Alaskagunslinger]

Thanks everyone for your response I appreciate it and I am passing info on to dealer mechanic.