Re: Boat Engines


I’m new to boating and am wondering if the engine I’ve bought has a problem or if my experience is normal.

I had my boat at home on its trailer with the OB down in its ‘running’ position’ – its a 4M fibreglass runabout with 25HP Mercury OB. I ran it with muffs connected to a hose for about 4 minutes – between idle and probably 2/3rds full revs. The ‘tell tail’ water flow was good and the engine sounded good.

I then cut the engine, disconnected the muffs/hose, lifted the OB, and lifted the front of the trailer up and hosed down the inside of the boat – after taking the drain plug out!

After I finished, I left the boat to dry for about 1/2 an hour, then put the trailer back down on a level and pushed the boat into the garage. Once in, I put the OB back down into its ‘running position’ so that I can push it further in and close the door.

When I lowered the OB, I noticed that a small puddle of oil accumulated under it. On the flat concrete it spread out to about 10cm diameter. It was difficult to tell, but I think it was coming from where prop meets gearbox housing.

Is this normal? Is it just unburnt 2-stroke oil that pooled somewhere in the exhaust system when the OB was raised and then drained when the OB was lowered? I can’t think how it could be gearbox oil because it was not put in gear.