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Is this oil slick normal?

L

lightfoot1

Contributing Member
Got my dad’s ‘67 Merc 9.8 hp working again, but when I run it in a garbage can I get an awful lot of ugly grey/tan oil floating on top, is that normal for these old engines?
 
The thing I don't remember is that it continues to drip oil on my garage floor after taking it out of the "test tank" (garbage can). Eventually it stops, but I get about a tablespoon of oil on the floor, is this normal too?
 
Think of the gazillion gallons of oil that flowed into rivers, lakes and streams over the years from two strokes...

Jeff
 
From what I've heard, there's more DAILY leakage of oil from the bottom of rivers and the ocean that was spilled by the worse tanker screw up in history--and that's daily.

Apparently, oil (a natural hydrocarbon) breaks down fairly quickly and is absorbed by plant life in the area. Remember that huge BP spill in the Gulf of Mexico? Massive, years long pollution was predicted, yet it was gone mainly by itself in a few months.

Jeff
 
bilge rat jim said:
Where is the oil coming from?
Click to expand...

Well, millions of years ago there were Dinosaurs and plants that died and got covered in muck :)

Ok, you mean more recently.

This is a 2 stroke so the gas it burns is mixed with oil (typically at 50 parts gas to 1 part oil). The oil is "designed" to burn up completely if the motor is running at it's operating temperature AND it's perfectly tuned running at ideal atmospheric conditions.

Almost none of those (variables) all come into line at any given time, so after combustion you end up with burnt and un-burnt oil being forced out of the exhaust with other exhaust gasses/chemicals.

Their "path out" of the engine is down the exhaust housing (leg) and out through the prop (on thru prop exhaust models) or out the little port just above the prop (on earlier designs).

The inside of the exhaust housing also get "coated" in all that gunk so whatever doesn't (immediately) make it out of the exhaust slowly slithers it's way down (when the motor is sitting) and drips out.

Usually whatever doesn't end up in the lake will drip out on the road on the drive home from the launch to your driveway, but when you run it at home and then shut her down, the evidence will end up on the garage floor or the driveway (often alarming the owners who are not used to seeing it).
 
galamb said:
Well, millions of years ago there were Dinosaurs and plants that died and got covered in muck :)

Ok, you mean more recently.

This is a 2 stroke so the gas it burns is mixed with oil (typically at 50 parts gas to 1 part oil). The oil is "designed" to burn up completely if the motor is running at it's operating temperature AND it's perfectly tuned running at ideal atmospheric conditions.

Almost none of those (variables) all come into line at any given time, so after combustion you end up with burnt and un-burnt oil being forced out of the exhaust with other exhaust gasses/chemicals.

Their "path out" of the engine is down the exhaust housing (leg) and out through the prop (on thru prop exhaust models) or out the little port just above the prop (on earlier designs).

The inside of the exhaust housing also get "coated" in all that gunk so whatever doesn't (immediately) make it out of the exhaust slowly slithers it's way down (when the motor is sitting) and drips out.

Usually whatever doesn't end up in the lake will drip out on the road on the drive home from the launch to your driveway, but when you run it at home and then shut her down, the evidence will end up on the garage floor or the driveway (often alarming the owners who are not used to seeing it).
Click to expand...

What I'm getting at is are we all sure this is residual 2 stroke oil, or is it gear oil from a leaky driveshaft or shift shaft seal?
 
While it is "most likely" simply exhaust residue, given this a 9.8 and only holds about 6 1/2 oz of gear oil, simply draining and inspecting the oil for water intrusion would be smart.

But greyish/tan coloured "gunk" that is "floating" on top of the water certainly sounds like "burnt" oil, not gear oil.
 
I changed the gear oil a few weeks ago and it's blue, this is light grey/tan in color so I guess its just excess or unburnt oil slithering down the exhaust into my test tank. FYI I this was my dad's motor and hasn't ran in 35 + years. I just resurrected it with the help of this forum (thank you all very much!) and I'm thinking that it might need some running time to loosen up the rings.
 
Isn't it great to know this stuff about pollution. In the good ol days before GPS if you wanted too zero in on a wreck to fish it, you just you used your compass, watch and hoped for calm seas then started looking for the oil slick that leached out of the sunken vessel you were going too fish. O yea you can still do that today if you can't afford a GPS. NASTY STUFF war.
 
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