Pontoon Boat & Deck Boat Forum

Hey guys, would like to get your opinion on something.. We havent used our boat in about a month... so today ( saturday ) me and momma decided on a little lake time.. when we went to the storage building to get the boat, I noticed an oil stain on the floor immediately below the motor ( yamaha 75 4 stroke ). The oil stain was not very big, about 3 to 4 inches in diameter... I'm not mechanically inclined at all, but I looked over the motor and noticed there was a film of oil on top of the fin on the lower unit... just above the fin, near the front end of the motor there is a screw that says "oil level"... I couldn't feel any oil on the bottom of the screw, but the oil film on the fin was from directly below the screw to where the fin slants downward... there was no oil film on the fin from the screw up toward the front of the lower unit... Do you think the oil is ( was ) leaking from the oil level screw.. I'm not sure where else it could have come from, so that's why I'm asking you guys that know these outboards in and out... I was able to turn the oil level screw, but not by much... about 1/8th of a turn and it felt like it was seated... didn't want to strip it so I stopped there... anyway, when I took the boat back tonight, I put a small piece of plywood below the motor to see if anything else shows up... just wanted to find out if you guys think I may have another problem.. thanks..
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If the screw was loose, it could definitely leak oil. That screw should be tight. There should also be an o-ring on the screw to help prevent leaks.

I'm not too far from you visiting relatives in north La as I write this reply.

You probably need a new O ring.

If oil is leaking out, WATER is getting in. Better check by draining and refilling. That is after you fix the problem with new O rings.

jimrs wrote:If oil is leaking out, WATER is getting in. Better check by draining and refilling. That is after you fix the problem with new O rings.

Yep, best to drain, refill and install new o-rings to be safe.

What they said change it and replace the seal.