This has got me concerned!

[Old Tyme]

Can anyone tell me what this pinhole is? I can't believe that it's supposed to be there but noticed it on 2 of 3 Mercruiser's that I have.
It's got me really concerned as when draining the oil from the drive, about 3 cups of water drained first before the cup or so of oil.
Thoughts anyone?

 

[chaparall villain 2]

Re: This has got me concerned!

nope its not supposed to be there ... it surprises me there is not lower unit lube leaking out of it i would drain and try to patch it

 

[Anchor Management 1]

Re: This has got me concerned!

It is a drain hole ,so water will drain out for the winter and will not freeze and break the drive. You will need to pressure check the drive to see where the water is getting in from.

 

[Old Tyme]

Re: This has got me concerned!

I found that the hole is a cavity flush hole and was installed on pre-alpha and alpha lower units from 1974 - 1990 and can be added to units prior to 74.
It's purpose is to allow sand to flush out of the cavity in front of shift shaft bushing hole.
Also, at 2nd investigation I noticed that the rubber washer on the oil drain plug was deteriorated so that would explain water getting sucked into the oil???

Thanks for the replies!