Oil Sheen- 2003 F225 Mercury "Yamamerc" 4 stroke

[Salt Shaker]

Greetings from the Keys! I'm actually posting this question for a friend. No issues with my F150 now "knock on some wood", although El Raton ate my trim tab wire last month. Had to run new wire and eliminate El Raton!

Buddy has an oil (or fuel) sheen surrounding one of his motors. Local Merc mechanic has looked it over and found no noticible signs of leak anywhere and went so far as to inspect the mid section and exhaust port. During a pressure test of the lower unit, the prop seal, lower unit seal (lower shaft seal maybe?) failed and was replaced. No evidence of water intrusion in the lower unit oil. As the engine is tilted down, the sheen starts and continues when motors are down and at idle.

Mechanics are stumped. The troubleshooting and "replace things until it's fixed" technique is getting expensive for him.

Any assist will much appreciated!

j

 

[fess]

oil from the trim and tilt?
oil from the steering?

 

[Salt Shaker]

No oil from trim tilt or steering. It appears to come from lower unit as it is dipped in the water and no visible run-down from exterior or inside mid section.

We are leaning toward oil as well because a couple drops of yamalube in the water looks very much like the sheen that we are seeing. Fuel seems to dissipate much faster that the sheen, although there has been some suggestion that a flooding VST may be sending fuel through the drain hose and down to the water. I would think that something like that would be more noticable to a mechanic though.

 

[Brent]

Maybe it's the drive shaft oil seal thru the oil pan.