I have a 1990 Evinrude 15HP that has served me faithfully for the last 10 years or so. Over the last couple of years it has developed the annoying habit of producing a lot of exhaust smoke even with fresh gas, correct oil ratio and properly adjusted carb. Engine idles well, starts easy and high speed is ok. Last fishing trip the fuel consumption was staggering. Normally a 5 gal tank lasts approximately 5 of my typical fishing days. lately I have to refuel after 1 .5 days and there's a lot more smoke and evidence of raw gas getting into the water. A 2 stroke motorcycle mechanic i know tells me this is typical (on motorcycles anyways) of worn crankshaft seals which permits some or most of the fresh charge which has just been inducted into the crankcase to be blown past the seals into the exhaust housing on the piston's downstroke instead of being forced up into the cylinder. He says this waste of the fresh charge would account for the high fuel consumption and the increase in exhaust smoke is due to the oil in the un-burnt charge burning off on the hot exhaust pipe which runs down the inside of the exhaust housing to the foot. What does get into the cylinder is still a proper mixture so the engine still runs ok and plugs appear ok. Does this make any sense before I tear the engine down?<br /> You can see I'm kind of hoping for it to be something else other than requiring a complete tear down. I want to go fishing !!
