What is this metal thing in the bottom of my engine oil pan?

[OneBoatman]

Boatpoker is correct. The picture is a partial top view of the bell housing which indeed has a hole in it. Altogether now. A bell housing is the enclosure which covers the flywheel and damper plate. Next, there is an adapter plate usually manufacturer specific which mates to the transmission. The adapter plate does two things: one it allows you to correctly position the transmission's input shaft and secondly it closes the bell once the transmission is bolted in place. The input shaft typically having splines which go into the damper plate and all told this how we initially capture the power from the engine. The transmission itself steps the down the speed and contains the gears and dogs needed to turn the output either clockwise or counterclockwise along with having a neutral configuration. Final drive at the output end of a marine transmission is a flange which allows you to mate to your drive shaft so that you are able to turn your propeller. The presence of hole may never do any harm however it is probably a good idea to seal it as you still want to keep debris and moisture in particular out of the bell housing.

[Cyrus Safdari]

Well, having disassembled the Beta I can't find anything broken but it does seem it has been rebuilt too
So it seems EngineMan was correct

https://www.cruisersforum.com/forums...ml#post3568599


This piece was left over from a previous rebuild, nobody removed it from the oil sump

[FPNC]

Originally Posted by kmacdonald

The hole may be for a tach sender. A magnet may be on the flywheel.

This is exactly what it is. The hole is used to position a Hall sensor or Mag Pick Up for a tach signal. There is not a magnet on the flywheel. It just picks up the the flywheel starter gear teeth as they spin past the pickup face. Fill the hole with some silicone and everything will be as it should be.