Hey all - I walked past my boat today and noticed it's leaking just a little gear lube down the skeg and dripping on the floor. It looks to be coming from the bolt that mounts the torque tab. Been about 2 weeks since it was on the water.
Is it stinky like sulfur or just an oily, gassy smell. If it's stinky and you find water in the gearcase when you pop the drain plug, you likely have a bad seal somewhere.
The most common leakage point is from the driveshaft seals. You can access those after pulling the lower unit and water pump assembly. The oil seals are pressed-into a square block that's held on to the gearcase housing with (4) bolts. If this is a fresh-water-run motor, the bolts will probably come right out. If they don't, or you have a Salty-Dog, the only way you'll get 'em out without breaking is with application of heat. A MAPP torch is best, it'll put out plenty of heat with no danger or melting parts. But you could do it with a propane torch if it has a good flame.
Here's a parts breakdown to give you an ideal of what you'll need for this job (usually just the seals and an O-ring for the driveshaft bearing/seal carrier):
Part numbers 3, 4, and 5 on the diagram. Note there are (2) seals, one with lips down and one with lips up.
If the leaking isn't obvious, you may have to pressure-test the L/U to approx 12 psi to find a leak.
Upon reassembly, put a light coating of Permatex #3 around the bearing carrier O-ring and also on the bolt threads. Guaranteed they'll never seize.
All that being said, it's not uncommon to see an oily discharge run out of the nether regions. If it's not stinky, but only oily-gassy smelling, it's probably just "mung" from the exhaust. And especially if your gear oil shows no sign of water. Because, invariably, if oil escapes the gearcase, it will be displaced by water.
I didn't smell it, but it didn't look milky. In fact, now that you mention it, it looked sooty like maybe exhaust mixed with water. The last day on the lake was a company event where i was giving boat rides, so I ran it all day with the boat loaded heavy. I'd bet I've just got some out-of-the-ordinary exhaust buildup with some oily blow-by.
I'll check it and get back with you. It's about time to do the impeller this winter anyway, so it would be a good time to do the seals too if it IS a problem.
Maybe a good idea to throw some Seafoam or Gumout Regane carbon-cleaning additive in the fuel. Regane is cheep at Walmart and highly effective, with a high load of PEA (polyetheramine) which cleans carbon deposits like crazy.
Sure sounds like combustion products to me. Cheers.......ed