Lower unit hole

[deernrams]

"1970 115 mercury. I would lik

"1970 115 mercury. I would like to know what this small hole does. Standing with boat on left and lower unit on my right. Start from right to left there is the flush screw, then the top lower unit fill screw then a small hole closest to the boat. There is 1 on both sides and they seem to line up. Does it help cool anything? Why is it there. Thx in advance."

 

[not-a-student]

It is simply a drain for a cas

It is simply a drain for a casting cavity.If it was not there water in that cavity would freeze and crack the housing.I have seen guessers plug those holes with RTV and the likes.Many times these holes are also plugged with sand and debris.Keep them clean and enjoy boating.