Oil/Gas in the water

[cashcrews]

2002 Johnson 40hp, 2 Stroke

Seems to be oil or gasoline, or a mix of both in the water when I bring the boat to a stop. Especially noticeable as an "oil slick" when I pull up to a dock/boat landing. Not good.

There is no discernable leak when I have it on the trailer, out of the water. I only notice this when it's in the water, right after running the outboard?

Any ideas? I need to get this fixed just for the environment's sake, but I'm also concerned that it could be the telltale signs of an engine problem in the works.

Cashcrews

[mrjigger]

Sorry I cant offer any suggestions to fix your problem, but I have a 1997 johnson 30hp 2 stroke that has been doing the same thing. just noticed it this year. I've looked the whole engine over and just cant seem to find the source of the leak. i would be very interested in any suggestions people may have.

[New Yankee]

Cash and Jigger,

Not wanting to over simplify the matter, but given that this is the first of the season, couldn't what you be seeing be the unburned fuel that typically dumps into the cowl when the motor is tilted and/or the usual grime/gunk that accumulates (particularly after fogging a motor for storage) that is being washed out by the unburned fuel and out the drain holes? When you stop some water back wash is likely splashing up to later drain a bit(?)

Just a thought.... Maybe Suface Tension or Valv can chime in.

[cashcrews]

NY,

Could be. I have run the motor quite a bit already this year though, so I'd think any fogging oil should be outta there by now. Perhaps I'm not following exactly what you posted.

cashcrews

[New Yankee]

In my old (80's) stuff when I tilt the motor for trailing some gas tends to seep from the carbs down to the cowl - may not be the proper term, but the bottom plate that surronds the block that your cover latches on to.

That residue will drain out, and create a bit of a 'slick' with even evaporated fuel when you get it wet - a small amount of water will cause a relatively large looking spot (for me it's less than a foot in diameter) in the water behind you.

Don't know if you've got thru hub exhaust which will also leave a bit - but since you run late model stuff that may not be a good answer either - the older stuff did it pretty bad.

Again, may be wrong - just my two

[mrjigger]

yankee, after looking over my engine a number of times

that was also the only explination i could come up with.

however, i cant ever remember it doing that in years past

after tilting the motor into the water from a tilted position. i have even tried disconnecting the gas line and letting all the gas burn up before trailering the boat. that did seem to help a little, but did not completely solve the problem. and it did get quite old waiting for the gas turn burn. anyone else have any thoughts.

[cashcrews]

My issue isn't necessarily related to tipping the motor up, from what I can tell. I don't tilt the motor up beyond the normal trim range when I'm trolling, etc.

When I shut the motor off and troll with the electric, for example, I will see little bubble/bursts of a petroleum-based product when it enters the water. This occurs in the water behind the boat. It will continue to do so for quite a while. If I remain stationary when I turn the motor off, such as at a boat landing, by the time I return from the parking lot there will be a thin oil slick the size of the entire ramp area surrounding the boat.

I have noticed an "oil smell" somewhat stronger than I'm accustomed to, this is present whenever I'm running the outboard.

[New Yankee]

Sounds like an issue if it's that big cash. Last thing I'd think of is a prop shaft seal, i.e. gear lube, but the way you describe the slick it would seem more likely gas (?).

I guess theoretically you could have a blown head gasket that is leaking fuel/exhaust into the water jacket, but if it runs well.....

My limited intelect has been exhausted - just ask my wife

Sorry couldn't be much help guys.

[ChuckN]

I would concur with the prop seal. I've had it happen to me, same unknown oil slick. Unscrew the bottom-most drain plug on the lower unit. If the lube is milky, or water comes out first, there's a good chance you found your problem.

Check the prop for fishing line (take prop off), that usually burns up the prop shaft seals nicely and you wouldn't know until you see the slick on the water or water in your lube.

If that's not the issue, move on up. Fuel line leaks under the hood, etc..