Notice of Fuel Slick, Exhaust?

[Jason2tpa]

Noticed this fuel slick immediately after cold start. Looked to be emanating from the exhaust. I couldn't tell if it was exiting as vapor or liquid before reaching sea water. Either way, it kinda concerned me. No signs or symptoms of any combustion issues while underway. Perhaps this slick represents fuel that was not ignited when I last ran engine on flush, which was 3 or 4 days ago. Any ideas, concerns, suggestions, etc?

[walleye1]

What is it? It does help.

[dray0151]

What is it? It does help.

I think OP's other post was about a 1985 90ETLK don't know if this is same engine or not. He had carb problems on that.

[Jason2tpa]

What is it? It does help.

Ah, my apologies. The change over to this new forum format no longer lists my engine specs. 1998 S115TLRW

[TownsendsFJR1300]

Your signature with engine info is now showing Jason.

As the engine seems to be running fine now, I'd keep an eye on it.

Perhaps check the spark plugs and the fuel pumps for slight leakage.

A failing fuel pump diaphragm may have seeped excess fuel into the crankcase and eventually into the water..

[Jason2tpa]

Your signature with engine info is now showing Jason.

As the engine seems to be running fine now, I'd keep an eye on it.

Perhaps check the spark plugs and the fuel pumps for slight leakage.

A failing fuel pump diaphragm may have seeped excess fuel into the crankcase and eventually into the water..

All good suggestions, thanks Scott.

[DennisG01]

Since it's a 2-stroke, especially an older one, I would think this is pretty normal, no? They're not exactly known for being "clean burning", after all. I've seen this on many of my/family's 2-strokes. I think it would also be normal to be in an overly rich condition when first starting a 2-stroke, too.

[panasonic]

I take it that you have not noticed this before? Perhaps your prop shaft seal could be leaking a small amount...not enough to drip on the ground but enough to see when you put it the water. Might want to have a quick look at that along with the other suggestions.

[99yam40]

All it takes is one cylinder not firing,burning the fuel running thru it to dump into the water to look like that

[Jason2tpa]

I take it that you have not noticed this before? Perhaps your prop shaft seal could be leaking a small amount...not enough to drip on the ground but enough to see when you put it the water. Might want to have a quick look at that along with the other suggestions.

At the boat ramp there always seems to be a fuel/oil slick hanging around. I've noticed a slick around my engine at the ramp, but never this much and never this obvious the slick is coming from my engine. Can't say I could tell the difference between the look of a fuel slick and gear oil slick. Do you? Is pressure testing the gear box the best way to go about checking the integrity of the prop shaft seal?

[Jason2tpa]

All it takes is one cylinder not firing,burning the fuel running thru it to dump into the water to look like that

No doubt about this ^^^. But in my case the engine is running at max performance, no drop of cylinder or miss firing.

[DennisG01]

You may be looking for an issue where there is none (see my post above). Sort as a tangent to this, what do your plugs look like? All similar and healthy?

[TownsendsFJR1300]

If the engine is running good and the "slick" is larger than normal, it wouldn't hurt to pressure check the LU.

(No oil in the LU when checking)..

[Jason2tpa]

You may be looking for an issue where there is none (see my post above). Sort as a tangent to this, what do your plugs look like? All similar and healthy?

I don't disagree with your input. No doubt older 2 strokes are known to run rich as burn through oil. However, my engine has been so well maintained through the years that I guess you could call it an abnormal older 2 stroke...in that it doesn't run overly rich and it doesn't burn through oil Haven't checked the plugs because the engine's superb performance contraindicates an issue with spark.

[DennisG01]

But... it's not about your engine being healthy or not. It's that ALL 2-strokes do what you are seeing. It's the nature of the beast. It's quite possible that the water conditions and sunlight conditions were such that it made the slick more noticeable. And, maybe it's been there before but you just weren't looking? Plus, think about what happens when you start up a cold engine... gotta prime it, right? That usually means a little extra fuel. The spark plug condition (color, etc) will tell more than just spark - it will tell HOW that cylinder is burning... meaning it's not just an "all or nothing" thing. If all look good and consistent, then it reassures you that everything is firing properly and could be chasing a non-existent issue.

This next comment does not negate gear oil leaking out, but do you have any water in the gear oil?