Vent plug hole on lower unit stripped

[pinsandfins]

Does anyone have experience with this??? I was changing my lower unit oil as I do every year at this time and went to screw my vent hole plug back in and there was nothing there to thread to. It's on a merc 225 efi. This is an aftermarket lower unit tho

 

[silvertalon]

Never seen the threads strip out of a plug hole like that. You may need to tap it and install a Helicoil. Or, just tap it for a brass plug. Be sure to use grease on the tap to collect any chips or shavings. You'll also need to use some RTV Silicone on the new plug threads. The SEI grarcase is actually pretty good. I have one on my 225 Merc and I tried a Merc factory gearcase. The SEI actually runs 2 mph faster on my 21 Triton.

 

[fischnrod]

https://www.youtube.com/watch?v=sz2yZNqGNqo