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gas in oil crankcase. How else could gas get into oil.

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  • gas in oil crankcase. How else could gas get into oil.

    Changed plugs, filter, oil, before. Fuel pump on motor tests ok

  • #2
    Gasoline crosses the piston rings and winds up in the crank case. Not uncommon on all brands of four stroke motors. Depends upon how the rings were broken in, the usage pattern of the motor, carbon build up on the rings, and a number of other factors.

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    • #3
      It is referred to as "making oil". Google it.

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      • #4
        A thermostat that is stuck open can cause it also, running cold.

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        • #5
          Many 4 stroke outboards increase oil level in cold weather due to condensation from not getting warm enough. Could also get gas in oil by running too rich which it will do if running too cool especially if fuel injected.

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          • #6
            Also, when changing oil only fill to the half to 3/4 mark on the dipstick. Need to have an
            air space in the oil pan so moisture and gas will evaporate.

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            • #7
              What kind of problems could develop if motor was run with the mixture of gas and oil?

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              • #8
                It will thin the oil out. what motor do you have? Nice to know what we are talking about.

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                • #9
                  Originally posted by walleye1 View Post
                  It will thin the oil out. what motor do you have? Nice to know what we are talking about.
                  We have done so much with so little for so long that we can now do everything with nothing at all.

                  I am guessing that it is a four stroke of some kind. Might be a Yamaha brand. I have been known to guess wrong. A Pratt & Whitney PT6 perhaps?

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                  • #10
                    You need to be like Don Weed European marine on bbc merc boards.

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                    • #11
                      Maybe it's one of these!
                      Dennis
                      Keep life simple, eat, sleep, fish, repeat!

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                      • #12
                        F90TLR 61PL fuel injection. Checked oil 9/13 and saw it was tan in color. Thought I blew head gasket or worse. Oil smelled like gas I was told gas can move into motor from temp change etc.Changed oil.filter, plugs. 10/13 took 45 minute cruise on plane and wake zone speed. Noticed some hesitation when getting on plane(4 men in boat).10/15 went fishing. noticed motor a little rough at no wake speed.10/24 took out boat again. Same symptoms.10/ 30 Fishing trip. Checked oil and found tan color again and oil overflowed when I removed dip stick. More gas in oil. Fuel pump clearly visible on back of motor checked out ok. No gas leaking when pump removed and bulb squeezed Diaphram and plunger seemed ok. Could it be the other pump located mostly hidden around the manifold? I've been told that's pretty pricey.

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                        • #13
                          What did the leak down test show?

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                          • #14
                            to much fuel pressure,the VST overflowing into the air box,most likely it is way over propped.
                            overpropping can and will make oil and rapidly.
                            what is the max RPM with your buddies beer and accessories? must be 5800 min or your over propped.

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                            • #15
                              Will the fuel in oil cause the oil to be tan in color?
                              I thought moisture would do that.

                              also need to be checking oil more often until you find a cure for what is happening.

                              not running properly means you need to be checking to see what is wrong,not keep running it and hoping it gets better

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