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Yahama F115 4 stroke getting gas in crankcase?

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  • Yahama F115 4 stroke getting gas in crankcase?

    2001 F115.With 5 quarts of new oil dipstick reads 1/4 inch below high mark. After running 15 to 20 hours the oil level rises to as much as 1 inch over the high mark on the dipstick.It runs very well[no smoking]but has stalled a few times when idling when the oil level reads high.It has been serviced by the dealer several times and they say they spoke to Yamaha about it and it can't be gas.They have no explination for high dipstick levels.


  • #2
    Re: Yahama F115 4 stroke getting gas in crankcase?

    Hi I had a problem like that ..It was on a four stroke motor and ended up being the electric carburetor fuel switch was not working and as the motor sat not being run fuel would flood into the carb and drain into the motor oil...to repair we install a inline shutoff valve to turn the fuel off when not in operation.......Hope you fix is that easy...Good Luck....

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    • #3
      Re: Yahama F115 4 stroke getting gas in crankcase?

      Had the same problem with my 100 HP Yamaha four stroke. I e mailed several certified Yamaha Technicians and they replied that I was to disregard the factory break-in instructions and run the **** out of it!!!!The fuel is diluting the base oil and if you don't run the motor hard, the rings will never seat. I had pretty much finished the suggested break-in by this time so.......I ran the heck out of it! It seemed to do the job! This is the second season on this motor here in Maine and couldn't be happier with the package. Be sure to change the oil often till you get the level to stabilize. One Yamaha tech told me that these motors can take three years to break in!!!

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      • #4
        Re: Yahama F115 4 stroke getting gas in crankcase?

        I have a 2001 F115 Yamaha 4-stroke with 11 hours on it so when I read your post this morning, I went and checked the oil level and sure enough, it was waaay over the full mark. In fact, the dipstick was completely covered. The dealer mechanic said not to worry, they would drain, refill, and then advised me to run the engine full rpms up and down in order to fully seat the rings. At delivery this Spring, I was advised to keep the rpms below 4000 until the motor had 20 hours on it, but the mechanic said forget that and go for it. Corresponds to what Edgewater techs told him.

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        • #5
          Re: Yahama F115 4 stroke getting gas in crankcase?

          Hi folks. Just a couple of comments.I don't think there is any way for that much fuel (or any fuel) to get in the crankcase. This engine is multi-port fuel injected, and without electronic activation of the injectors the fuel can not enter the cylinders. If fuel was entering the crankcase, you would not only have a serious safety problem, you would notice a smoking exhaust and your oil would become very dirty very fast. Even poorly seated rings won't generally allow fuel to enter the crankcase. It usually gets burned first at ignition. However, oil can enter the cylinder. I suppose a true oil analysis would indicate if fuel was in the oil or not.After running the engine, the oil will be hot and expand it's volume considerably. Since the crankcase reservoir on your F115 isn't like the long, flat oil pan on your auto, you will notice more of a difference.Also remember after the outboard sits most of the remaining oil in the filter will drain back to the crankcase. This will make a difference too. And don't forget that you may not have gotten all the oil drained out at your last change (depending on drain angle) which would add to the 5 you just added.The biggest culprit could be the tilt angle at which you are checking the oil.My F115 manual says 4.8 quarts without a filter change and 5.0 quarts with a filter change. The 5 quarts and a new Yamaha filter work for me and I haven't noticed any over-fill.I did break-in my F115 as suggested and would not recommend running the snot out of it until its time. Break-in for this outboard is 10 hours. The rings will eventually seat. Running Yamaha's sythetic oils will only slow the ring seating process. Run the outboard at half throttle or below for the first hour. For the second hour run it at three-quarter throttle with occassional one minute bursts of full throttle every 10 minutes. For the next eight hours avoid continuous full throttle operation. Then, after 10 hours run the snot out of it. Worked for me. She's a sweetheart.

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          • #6
            Re: Yahama F115 4 stroke getting gas in crankcase?

            Good point! I recomend the manufacurer's break in and then run the heck out of it. You had mentioned the fuel injection issue but my F100 has the carbs.I had to change the oil three times last season due to the level becoming higher than recomended. The engine had 24 hrs to cool down and I was careful to try the various tilt angles. When I'd drain the oil for an oil change, it was done when the engine was warm so that I'd get a complete drain. 4.8 qts. is also recomended for my engine but still after about 10 hrs the level would be high after adequate cool down.Now that I've completed my break in period and have ran it strongly for most of the season, the oil level appears stable.Other than this small glitch, the motor has been great!! I **** near hug it after each Striper hunt. The Economy is equal to or better than my 14 ft alum. skiff with a 25 hp merc.Thanks for your input!

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            • #7
              Re: Yahama F115 4 stroke getting gas in crankcase?

              Have seen a few 115 yams at the marina with water getting into the crank case. seems to be a problem with the water pump shaft seal on the 4 strokes. it just goes to show you that all brands have their share of woes and all the merc bashing by yam owners is blown out of proportion.

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              • #8
                Re: Yahama F115 4 stroke getting gas in crankcase?

                It's a long ways from the water pump shaft seal to the powerhead..........Rotating shafts will lift water but there are a few other safe guards in the way.No Merc bashing here either.......Love my Merc also.

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                • #9
                  Re: Yahama F115 4 stroke getting gas in crankcase?

                  Edgewater : I may be wrong but it appeared that the pump was mounted on the back of the power head on the 4 unlike conventional which is down in the lower unit. in any event i saw 2 in my marina with the same water in the crank case and the owners both said it was from the seal behind the pump.

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                  • #10
                    Re: Yahama F115 4 stroke getting gas in crankcase?

                    robt,Remember, anytime a four stroke engine gains fluid in the crancase, it can only be two things.1. Fuel.3. Water.This is easily diagnosed by a "smell check". What does the oil smell like? Typically, if it's water, the oil will be "milky" and smell moldy.If it's fuel, it will smell like fuel.I would guess it's fuel. Remember, a four stroke outboard does NOT have:1. A thermostat with a high temp. rating that will burn off unburned fuel-like an automobile.2. An evaporative emission system that draws off unburned fuel (hydorocarbons).I think the others have made some good points about ring seating. Once you're past the break in period, this is imortant since you're also braking in the lower unit. Once past, run the daylights out of it and remember to vary your speed alot. The up and down of rpm. helps to seat both sides of the rings.

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                    • #11
                      Re: Yahama F115 4 stroke getting gas in crankcase?

                      Kidstuff, your oil pump is mounted at the bottom of your camshaft in the area you describe, but the waterpump is in the traditional place in the gearcase.Djohns,where did that info come from?Are you sure about that?I agree on the oil analisis ,but have you looked at a current fourstroke, or felt one warmed up?

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                      • #12
                        Re: Yahama F115 4 stroke getting gas in crankcase?

                        My take on this is not to run it at all if the oil is getting diluted from gas OR water. Either one can cause rapid wear (but your rings will seat fast). One inch on that dip stick is a lot of extra fluid. Like dejohns say...the oil will be milky with water or smell like gas. Very easy to tell. Check it hot to see if the problem is water...don't let it sit. Like forktail says, if getting blowby into the crankcase the oil will get black real quick too.From that I'd say it is a leaking head gasket or a fuel leak from the carb into the crankcase. There may be a fuel pump diaphram leaking too but I don't know if Yammys have a design that can do that. Someone posted on another message that their 4 stroke got water in through the exhaust when sitting at the dock. What I do know is I wouldn't listen to any mechanic that told me to run the snot out of my engine to burn off 1" of additional gas or water in the crankcase. It could be that I'm real stupid and don't have a clue too...but I would wager that the Yamaha factory would tell you not to run it either.Let us know what you find.

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                        • #13
                          Re: Yahama F115 4 stroke getting gas in crankcase?

                          I'm still not convinced you have gas or water in the oil.A simple oil analysis is the only true way to know unless, as others have said, there is milky oil or strong gas smell in extremely black oil.Chances are robt268 it was an overfill/underdrain, heat expansion of the fluid, or a possessed dipstick. Hopefully these F115's are built tight enough to keep fuel from entering the crankcase during break-in. Most 4-strokes are, and they certainly sound tight.I did find it odd about the stalling. I can't ever remember mine ever stalling. Not even once. Maybe that's an indication of some other problem?

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                          • #14
                            Re: Yahama F115 4 stroke getting gas in crankcase?

                            robt,One other thought.I believe your Yam. is EFI. If so, a leaking fuel injector could cause this. Also, the fuel pump may be oil cooled-not sure. If so, I would suspect a leak there. If it is indeed fuel getting into the oil.

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                            • #15
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                              Re: Yahama F115 4 stroke getting gas in crankcase?

                              Next time your oil is way up on the dipstick, drain it and see just how much is in the crankcase. Put a drop of whatever is in the crankcase on something hot (in a car, use the exhaust manifold). If it bubbles and bounces and then goes away, it's water. If it just spreads out,it's oil. Put some in a small container, and if it burns real easy, it's has fuel in it.c/6Hooty

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