purpose of "water inlet cover" yamaha 30

Before removing the lower unit on my 1990 yamaha 30, (30eld), i tried removing this part, and the screws were seized up so i ended up breaking this cover in order to remove it. Ive put it back together using some waterproof adhesive. Just wondering what function this peice serves? It was originally screwed in to place like i said, forming a tight seal, so i figured using adhesive wouldnt be so bad since i cant see any useful purpose for this peice. If anyone knows what this is for, please tell me. The photos here are of the lower unit upside down on a workbench. the small black rectangular peice is the part in question. on the various yamaha parts diagrams found online, it is referred to as "water inlet cover". Thanks.

 

I looked on my 25 hp and its open ..the cover has gone..as its upside down why not pour some water in it and see where it comes out ? then deceide if you think it should be blocked off as intended....

 

well ive already sealed it up with adhesive so that wont really be able to happen. on the other side its just basically a funny shaped chamber, as it is where it meets the middle casing where the lower unit attaches. no tubes or pipers or anything, just basically a wide open cavity. im starting to think maybe this lower unit came from a different year motor.