is it normal to have carbon run down on exterior of exhaust housing?
 

hi all,

I've noticed a small amount of oil or carbon(not sure what it is, but
it's dark brown and thick) running down on exterior of the exhaust
leg(on the side facing the transom) starting from the inside of where
the upper unit and the exhaust leg connect. my outboard has a thru-
prop exhaust and I thought carbon (if that's what it is and not a oil
leak)only oozes out of the prop. Is this true or is it a leak? My
prop is very dry not a drop of oil or carbon.

the outboard is a 83 evinrude 90 hp. thanks in advance.

s o