98 rude 4 stroke gas in oil

S

stag

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Jun 29, 2009
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98 70hp evinrude/suzuki 4 stroke fuel injected. thought there was gas in the oil since it was a couple quarts over full. the engine would not turn over because the bottom cylinder was full of oil/gas. took it to dealer who replaced fuel pump diaphram and changed oil. ran it a couple of times and noticed a little gas in the oil. did not use engine over the winter. checked oil a month after summer started and gas is back in oil. i changed the diaphram again. ran it a couple of times including letting it sit between weekends. same problem. looked at old records and seems like this has been happening since purchased. is it possible one or more fuel injectors is leaking, then the gas leaks past the rings into the oil? Is there any other way for gas to get in the oil?

Any ideas are appreciated.
Stag
 
S

stag

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Joined
Jun 29, 2009
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2
Re: 98 rude 4 stroke gas in oil - making oil

Re: 98 rude 4 stroke gas in oil - making oil

I can't thank you enough for the reply and the web site. That was a very professional and well thought out response. I looked for hours and never came close to that explanation.
The vast majority of my mechanic experience is on automobiles which may explain my next train of thought. I was surprised he did not discuss the appearance of the oil. In cars, when oil mixes with water, it foams. I realize the synthetics, especially those formulated for boats, may be less likely to foam but my motor locks up after enough "oil has been made" becuase it floods the lower cylinder - either from the crankcase or fuel injector. Compression is the same in all cylinders so I am doubting a bad gasket letting the water into the cylinder - but I am not a boat mechanic so I welcome being corrected. I always run it above 3k rpm usually closer to 4k. Top rpm is about 5k on my pontoon boat. The boat is stored on a lift just above the lake.
With all this do you believe the motor can have 3 or more quarts of water condensate into the crankcase in 3 months of use?
 
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