Changer Lower Unit Oil - Oil seeping from vents

I changed my lower unit oil today and later saw a few drips of oil coming out of the vents on the lower unit a little later after trailering.

Anything to be concerned about?

Did you replace the gaskets? Also, depending on lower unit, some (I know my TM) need to drain about 1.5 oz out after filling to allow for expansion. You can blow a seal if not.

Didn't have replacement washers but the old ones looked good. No oil leaking from the plugs, just the water intake holes, but just a few drops.

I was not aware of letting some oil out for expansion but will check with Mercury for the specs.

The only way oil can come out of the water pick screens is if you shift shaft seal or drive shaft seal is leaking. I wouldn't keep running it!! You need to get someone to pressure it up and see where the leak is. A seal cost a whole lot less than a lower unit!!

X2

It may be a few drops setting on the trailer at the ramp, but once you run it a lot more comes out. Sounds like you may have overfilled it and caused a seal to fail.

After changing lower unit oil, I always bleed any pressure or overfill off by running it and getting the oil warm, put it back on the trailer and then crack the bleed screw. This is especially important on Mercury torquemaster and sportmaster lower units.

This is very true---When the oil heats up, pressure builds and expands causing seals to fail.

If you follow the procedures for filling the gearcase you cannot overfill it! Pressure check the l/u and see where the leak is.

Bet its the seal under water pump only place you see oil in water pick ups