Hey guys, I let my buddy borrow my boat the other day and told him to give the shaft zerk a couple shots of grease before he took it out. I hadn't greased it in a while. I forgot to tell him to the over fill bolt before he greased it, and he said while he greased it, he heard a pop in the motor. More like a ping. Any idea what this was? I'm not very knowledgeable on these motors since I just bought it a year ago. I assume there is a seal back there and I hope he didn't blow it out with too much grease. If he did, what are the consequences? He said it ran fine, and then I ran it when I got it back and there didn't seem to be anything wrong.

Just kinda worried there may be a problem I can see that will rear it's ugly head at bad time. thanks

Get an 8mm allen wrench & remove the clutch cover bolts. Depending on year model, the cover will either be sealed with silicone or an o-ring gasket. If it's siliconed, you will have to pry it off, if it's the o-ring, hold ya hand on it so it don't fall off. When ya remove the cover, look inside to see if grease has been slung everywhere. If there's grease, then the seal is blown out.

To replace it, remove the rest of the bolts & the lower unit. Stand it on the prop end, being carful not to hurt the prop or threads. Remove the 2 allen head set screws that hold the gear & cone together. Use a rubber mallet to knock the gear loose from the cone by driving the gear toward the housing. When the 2 seperate, remove the cone, then the gear. The seal will be exposed for you to change.

Deadbird8 has a very detailed post about it on the MB forum if you need step by step info.
FYI, the seals from MB are not very expensive, but definitely worth the $.

The MB lower unit should be greased once a year, its not really something you want to shoot a few shots of grease in ever so often. There are detailed posts on the operation on the MB forum. There is also an exploded parts view of the lower unit on the MB customer page.

If you blew the seal then remove the taper lock as said TC posted. If the taper lock is hard to get off see the post I put up over there for changing the lower gear. There is a split ring washer behind the spacer on the gear and once removed you can use a screwdriver to pop out the seal and install a new one. Use red locktite when putting the gear/taper back together.