2018 Merc 250 Pro XS 4S - Lower Unit Randomly Leaking From Nosecone

[99'Formula]

SN: 2B531199

Gents, I have a weird issue with my lower unit that keeps randomly popping back up. Every so often I will have a little bit of lower unit oil leak out of the nosecone when the engine is tilted up. It doesn't happen every time I use it which is the random part. I've taken it in to the shop to have looked at when I first noticed it. They pressure tested it, changed the LU oil (said the oil looked good), and said that they couldn't find anything wrong with it and sent me on my way. That was earlier this year. Since then, it has happened twice with the latest being last week. I plan on changing the lower unit oil next week to make sure that there is still no water in it since the temps are dropping and was wondering if anyone has any ideas on what to look at or do with this situation. Any thoughts? IMG_6580.jpgIMG_6575.jpg

[EuropeanAM]

Is the pitot opening plugged, perhaps?

[99'Formula]

Thanks for the reply Don. Its possible. I will go over to the storage and check tomorrow. For my knowledge, how can a clogged pitot cause the issue? Always trying to learn.

[EuropeanAM]

If the pitot is clogged, water can be trapped in the small passage, FREEZE, and then perforate the case (resulting in a pesky, hard-to-find leak).

[99'Formula]

Sorry got caught up with the holidays. I finally got a chance to take a look at the lower unit and change the oil. Pitot was clear and unobstructed. Doesn't mean that it wasn't once plugged but it is not currently. I went ahead a changed the gear oil. It was dark and needed to be changed but it didn't appear to have any water or debris. At the very end it did leave a light film on top. Not sure what that is or if it was just residue from the exhaust. I attached a picture of it. I'm not sure what else to do other than just keep running it and keep checking the gear oil. IMG_7944.jpg

[EuropeanAM]

I don't see any significant (or even concerning) evidence of water there.

[rocketmanjp]

Just a thought here. My orginal 300r was leaking oil out of the water intake passages on gearcase from get go. It was initially thought to be gear oil because the factory gear oil was gold. My dealer chgd the gear oil to the green colored HP gear oil so we could tell what was leaking. It was determined that it was engine oil & that there must be porosity in the block leading engine oil to the water passages. Merc replaced the entire engine.