Mercury Dripping Oil

My 2000 Merc 125 ELPTO is spotting some oil when I leave in on the transom saver. I’ve been using it to troll on Lake Superior, so it’s running at low RPM longer than usual, but I’m not sure that’s related. The oil seems to be coming from a BB sized hole above the lower unit, the lower unit oil is still in good shape and not milky. The oil that’s finding it’s way out seems to be globs and chocolaty looking. I’m thinking it is probably old oil draining out of the lower cowl from previous spills and warmed up enough with the long trolling hours to find it’s way out, but not sure enough to be comfortable running it long term like this.

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Keep an eye on the oil level in the lower unit, it may not be letting water in but it can let oil out.
That BB sized hole is a drain near the water pump housing if I remember right and there are seals in the lower water pump base, most likely this is where the oil is coming from.

Sounds to me like it is exhaust sludge draining out the hole. This is a 2 cycle engine correct? Incomplete fuel combustion will leave a residue. I would conclude, this residue “sludge” is what you are seeing.

Huntindave wrote:

Sounds to me like it is exhaust sludge draining out the hole. This is a 2 cycle engine correct? Incomplete fuel combustion will leave a residue. I would conclude, this residue “sludge” is what you are seeing.

It could be exhaust sludge but I didnt read where the OP said anything about it coming out of the prop or leaking around it where the exhaust is routed out of the motor.
Who knows, A leak test is the best way to test the seals and I havent figured out a way to do it over the net, need a transporter like on star trek.

Not familiar with a 2-stroke Merc but I do alot of trolling with a 2-stroke OMC and get alot of exhaust sludge.It also exits from a small hole near the lower unit and can get gobbed up pretty bad inside the housing.On my OMC it can be easily seen/confirmed when dropping the lower unit to do a water pump.I dont do enough on plane cruising so it builds up faster than it can disperse out of that pea shooter hole.I can say other than the mess it causes now and then it has never caused a motor issue for me and has been going on for years.

That Cream Cheese at the exhaust ? Not enough HEAT in the cylinder head. Cold thermostat. I changed it & the Cheese stopped. Along with a 2 minute run home at WOT. Cleaned off the plugs also. 10 hp Evinrude 2 stroke. Mixed at 50 to 1 ratio. I run some Seafoam in about every 5 or 10 tanks of fuel. No cream Cheese.
Correct oil to fuel ratio is VERY important in 2 strokes that troll a lot.

Thanks for the replies. Plugs are new and it’s oil injected so mix shouldn’t be an issue. I checked the lower unit oil level and it’s fine.
The only place that it’s leaking out is above the lower unit at the drain point.

It is 22 years old.
How do you know the water temperature is correct WHEN IDLING a long time ?
How do you know the oil injector is operating perfectly ?
Are you using the CORRECT 2 stroke oil ? 2 stroke AIRCOLLED ENGINE oil is cheaper & does not burn up during trolling.
Did you measure the sparkplug gaps ? Adjust them To be correct ?
If you idle / troll for long periods. Get a ….CORRECT HOTTER sparkplug. Most engines have them available from N G K Spark Plug Company.

Is the idle speed & mixture correctly adjusted when FULLY warmed up & in FORWARD speed ?
It is 22 years old & need a experienced mechanic. Lots of things he has to check & change. NAPA or other auto places do not repair motors.

I looked up you motor on the web. The motor runs on the TOP 2 cylinders ONLY at low speeds. So that may explain the excess oil dripping out. IF IF the engine does not stop oil to those 2 cylinders.

You need to chat with a Mercury Service manager.

R Petersen wrote:

IF the engine does not stop oil to those 2 cylinders.

Anytime the pistons in those two cylinders are moving, they will need oil for lubrication, doesn’t matter if the cylinders are providing power or not.

R Petersen i’m curious.Where did you get all this knowledge?

chuck100 wrote:

R Petersen i’m curious.Where did you get all this knowledge?

Ya, I’d like to know this too, I need a good tech in my shop that can keep up with me and has at least a few thousand hours of experience.

R Petersen wrote:

That Cream Cheese at the exhaust ? Not enough HEAT in the cylinder head. Cold thermostat. I changed it & the Cheese stopped. Along with a 2 minute run home at WOT. Cleaned off the plugs also. 10 hp Evinrude 2 stroke. Mixed at 50 to 1 ratio. I run some Seafoam in about every 5 or 10 tanks of fuel. No cream Cheese.
Correct oil to fuel ratio is VERY important in 2 strokes that troll a lot.

This is good advise. I replaced the thermostats in my 1996 150 Mariner, they were 2 if I remember correct. Parts $13 a piece. This was a few years ago, but super easy job. And if your thermostat/s are stuck open, the engine is not staying at a good operating temperature. This can cause problems in your cylinders and other parts of your motor. I do not know much about small motors, do the spark plugs/plug foul quickly? If you remove a plug and inspect the business end, is it wet?

I almost forgot about adjusting the idle speed & idle MIXTURE screws on engines with them.

Idle speed adjustment. Idle air / fuel mixture adjustment. Both to be done after engine is FULLY WARMED up. In FOWARD GEAR. You need to have the engine cover off of most engines to do these 2 adjustments. I usually borrow a automotive TIMING LIGHT to check if someone has misadjusted that also. My 30 hp Evinrude trolls in gear with the throttle plate completely closed.

The mixture screw …MUST MUST be set to the fastest & smoothest speed at trolling speed!!!!!!!!!! You want ALL THE HEAT you can get out of that tiny flame in the cylinders !!!!!!!!! It will help keep the plugs CLEAN for DAYS of trolling…… I troll a lot & putts around from place to place.