i have a new to me 50HP tiller. the motor is in great shape but hasnt been run since last fall. i started it today with the hose and ears. after i shut it down, i noticed some sludge like discharge coming from two weep holes(one on each side) down on the skeg. this was a very dark black/charcoal colored liquid with water in it. it slowly stopped flowing after a few minutes. what is this stuff and is this normal? anything to worry about? thanks alot, mark