Small hole in lower gear housing

Just noticed a small hole in my lower gear housing. (See attached pic) It's about 1/8" diameter and located above the prop shaft and below the bolt flange to the upper housing. Note that I forgot to check the gear oil for water before I took the boat back to the storage center.

Questions:
- Does this hole goes into the water jacket or into the gear case? I haven't seen a cutaway drawing of the lower unit so I'm not sure.

- Do I need to have the prop shaft assembly inspected and the gear oil changed?

- How should I repair this? Weld? Epoxy patch compound? Sealant? I want to make sure that any patch material doesn't fall inside the casting and cause other problems.

Please give me your thoughts. Thanks!!

Merc Alpha 1 Generation 2
Sterndrive 0W833328, T-5-121300T-S
Transom Assy 0W471278, L-6-111001L-S

Re: Small hole in lower gear housing

might be the speedo inlet

Re: Small hole in lower gear housing

Looks like the speedo inlet, don't cover/patch it.

Re: Small hole in lower gear housing

It's definitely the Speedo inlet. I have the same drive, same "hole".

Re: Small hole in lower gear housing

Thanks for everyone's help. I wouldn't have guessed this hole had a purpose. It looks like a nick. We messed up the prop at the beginning of the season due to the low water levels. I thought this was part of the damage.

Re: Small hole in lower gear housing

kellmike626 said:

It's definitely the Speedo inlet. I have the same drive, same "hole".

Click to expand...

Yep, all Mercruisers have them, Bravos and Alphas. And have for a long time.

When your speedo quits working (and it will) check that hole first for mud/debris. Carry about a 5" long piece of straight wire coat hanger with you, you'll need it.