Guest hewes Report post Posted April 2, 2011 i have a 2002 25 hp Johnson. I tried to start it and noticed black oily substance(smells like gas) coming from a small hole on the opposite side of the top oil drain screw between the two fins . low end oil is fine golden in color . the compression is great 120 psi .what is this stuff . fogged the motor in the fall Quote Share this post Link to post Share on other sites
naden 130 Report post Posted April 2, 2011 Not familiar with that motor and what the hole is but I am guessing it is the lower vent hole for the exhaust housing. Unburnt fuel and oil in the housing can mix with the carbon deposits in the housing and seep out the vent holes. Usually black and smells like fuel. In your case if you fogged it the fogging oil likely came out the exhaust port on the cylinder and mixed with the carbon in the housing and dripped out over the winter. Sometimes you will see that dripping out of the center of the prop or the upper exhaust vents as well. Quote Share this post Link to post Share on other sites
Guest hewes Report post Posted May 23, 2011 Not familiar with that motor and what the hole is but I am guessing it is the lower vent hole for the exhaust housing. Unburnt fuel and oil in the housing can mix with the carbon deposits in the housing and seep out the vent holes. Usually black and smells like fuel. In your case if you fogged it the fogging oil likely came out the exhaust port on the cylinder and mixed with the carbon in the housing and dripped out over the winter. Sometimes you will see that dripping out of the center of the prop or the upper exhaust vents as well.thank for getting back to me thats all it was a vent hole Quote Share this post Link to post Share on other sites