Fluid in sump oil. Yam 2005 F90.

[jdholt41]

Problem:
Gasoline(? or water) getting into the oil in the sump.
Engine: 2005 F90 LTRD 4-cyl. Very low hours on it.
History:
Noticed about 8 oz of extra fluid in the oil. Smelled like gasoline. Drained the sump. Dismantled the fuel pump and inspected the diaphragm but found no defect. Replaced the fuel pump with a new one anyhow. Had the fuel injectors cleaned (but not pressure tested). Put new oil in the sump.
Ran the boat for about 3 hours. Found about 6oz of extra fluid in the sump. Smelled like gasoline but the milky appearance looked like water. Engine ran fine and plugs are clean and appear to indicate clean ignition. Drained the oil and let it settle in a glass container for 48 hours. Upper 6/7ths of sample looked like clean oil; bottom 1/7th was light grey. Grey fluid at the bottom doesn't look water.
Is there any other way that gasoline can get into the oil other than through a defective fuel pump or bad injector? Or is this water, which might indicate a blown head gasket or ???.
Thanks,
John

[boscoe99]

Gasoline can get from the combustion chamber into the crank case. It is referred to as "making oil". A misnomer of course.

A thermostat that is stuck open can contribute to the problem. So can a lot of idling time. Cold water makes it worse.

Now sometimes there can be a carbon buildup on the piston rings that prevent them from sealing as they should. You can do a compression check and a differential pressure test to determine if the rings are sealing. If their is excessive carbon a dealer can remove it by using a very potent chemical that he has. Called Yamaha Internal Engine Cleaner. YIEC.

The assumption is that the motor once upon a time did not make oil but it is doing so now.

[fairdeal]

IMO fuel dilution (gas in the oil) is not going to look "grey".

Water/oil emulsion however is typically opaque - "milky" and "grey".