Re: Gas in Oil
I'll look at the clear tube, but I remember looking into the carb while it was running and wondering what that gasline was for...because as the boat was running no fuel was going into the carb from that tube. I dont understand why the fuel pump has any relation to the crankcase or why the two are connected? So if my fuel pump is bad i'll replace it, but if the gas is going into the crankcase....what gas is getting to my engine? Sorry so many questions, trying to understand.
Well it depends on what kind of engine and fuel pump you have.
If you have an ENGINE mounted mechanical pump and the diaphragm is leaking, it will leak right into the crankcase. For marine pumps they put a small clear hose on the pump so it can dump into the carb intake so you can see the fuel in the line. In a car or truck it would just dump on the ground (and into the crankcase).
The fuel doesn't stay in the oil for all that long though. Once the engine warms up, the gasoline will evaporate fairly quickly.
Gas in the oil doesn't really hurt anything. Back in the "Old Days" (before multigrade/synthetic oils) Aircraft engines had oil dilution systems. In very cold or anticipated cold weather, The pilot would open a cockpit operated valve right before shutdown and literally dump a measured amount of fuel directly into the oil. The gasoline would mix with the oil and dilute it sufficiently to allow an easy start the next day. When starting the engine, oil pressure would come up right away........then later, after the oil was warmed up the gas would evaporate (completely)
"Flooding" an engine with gasoline while running or starting doesn't put all that much liquid fuel into the oil because what gets there has to get by the rings. Unless you have really BAD rings (or no rings) most of it goes out the exhaust valve burned or not.
So in most marine engines gas in the oil usually comes from an, engine mounted machanical fuel pump, that has a hole in the diaphragm.
My 454 Bravo engine by the way cannot have this problem because the mechanical fuel pump is mounted on the raw water pump. (when I got the engine the tiny oil supply for the raw pump smelled of gasoline!.....So I replaced the pump)
