DF115 Fuel in Oil

[mesiders]

I have a DF115 and I was told that fuel pump problems put fuel in the motor oil and water in the gear oil. The water in the gear oil does not make any sense at all. I would like to know how the fuel gets into the motor oil when a fuel pump fails. Any comments would be appreciated.

[Harper2]

Water gets in the gear oil through the rear seal. If some fishing line gets wrapped around your prop shaft, it can damage the seal and cause the water intrusion. So you are right about that, it has nothing to do with the fuel pump.

The low pressure fuel pump is a diaphram pump, operated by a cam on the camshaft. Fuel can dilute the oil via a ruptured diaphram on the low pressure fuel pump, causing the fuel to leak into the upper cylinder head area then flow into the crankcase.

[mesiders]

Thanks

How do I know if the mechanic fix the fuel in the oil and the water in the gear oil?

[Harper2]

Well, that would be done pretty much the same as you would with your car. Ask the mechanic what was done, what you've been charged for, and if you deem it necessary, ask to see the old part that was replaced (best that you make that last request before you authorize the repair work).

[Moonlighter]

Plan B is to ask to watch while the work is being done!

My local Suzuki guy does mobile servicing so he comes to my home to service my motor, and is quite happy for me to watch. Happy to explain what is being done and I can see exactly what I am paying for.

[Harper2]

I think Moonlighter's idea is best here, but I have another question, too. I've been pondering your entire thread a bit, and trying to ascertain why you started the thread; whether you're asking about work that had already been performed, in which you were told "this is what we did and here's why" or is it that you are the one who noticed the fuel in the oil and water in the gear oil and have taken your problem in for analysis and repair, and gotten this opinion from a mechanic.

If the former, i.e., if this problem was discovered by your mechanic during, say a routine service job, and you did not know of the problem prior to the service, then initially, you'll probably just have to take his word for it. He or you would determine that there is fuel in the oil in noticing that the engine is "making oil" and the oil level is above the "full" mark, and continues to rise over time (and you can smell the gasoline in the oil), indicating that you are leaking fuel into the oil. The only way for you to check the gear oil for water is to drain a portion of it and observe it for a milky appearance, indicating to you that water has gotten into the transmission gears and mixed with the gear lube.

So.....if your thread is seeking advice on whether to authorize repairs that your mechanic says are needed, and he has told you why he has come to this conclusion, he should be able to show you the evidence, and yes, the work needs to be done. If the work has already been done (hopefully you authorized it) then at this point, you will probably have to take his word for the existence of the problem, and that the work that he performed was necessary.

[mesiders]

Complete story

Three months ago I took my boat in because it was dying when pulling the throttle back to idle and then it would not start (seems to be flooded). The mechanic replaced the fuel line in the motor, the spark plugs, lower and upper oil and filter. It was better, but still had some problems with it dying. In the three months I took the boat out maybe 6 times for short trips…using a half to three fourths of a tank of gas. The last three time out the boat died and was very hard to start and the last time I had to be pulled back to the dock. This time the mechanic replaced the fuel pump, spark plugs, lower and upper oil and filter and did a lake test I paid for. The only explanation I got from the manager was that the fuel pump breaking put water in the oil and fouled the plugs. That did not make a lot of sense to me and I think I paid for the poor job they did the first time. This thread is to get other opinions.

[Harper2]

Thank you for the explanation. It is difficult for the reader to understand exactly what the original poster is looking for if the explanation is not offered up front. I'm sure there will be more opinions offered to you now that you have better explained your situation.