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2001 Mercury 250 EFI Oil Leak

pprisco79

New member
I have observed a good size cloud of oil from my engine after its turned off. When I tilt it up, I see a steady stream of black sooty oil coming from a weep hole just above the lower unit. I know two strokes discharge some some amount of oil into the water, but I cannot remember this much during prior seasons. I took it to the local mercury dealer. They first drained and presurized the lower unit to rule that out as the problem. It held pressure and did not have any milky fluid. From there they determined that it was either a reed valve stuck /bent or the lower main seal leaking. After their estimates of several thousand dollars for exploratory type of repair, I decided to do the work myself. During teardown I removed the lower unit and looked up the lower cowling to see two different chambers, one for the shaft to the lower unit and another for combustion gases to exhaust thru the prop. With a flashlight in hand, it appeared that the oil was coming from the combustion chamber not leaking around the shaft. I did decide to go ahead with the recomendations of the dealer anyway. The reed valves were perfect, no bent or build-up. I just replaced all the gaskets and re-assembled. I did pull the entire power head and put a new lower main seal as well. However after all of that it appears to do the same thing. Does anyone have any sugestions or comments. All are appreciated! Thanks in advance!
 
Black oil/sludge is normal,as you say all the oil/fuel is not burned off and builds up over time and when warm slowly makes it's way down the exhaust tube.Bear in mind that I no nothing about these motors but I assume that there is an oil/fuel mixer on it and that it may be a richer mix going on,maybe have a look at that
 
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