What's This & What's Its Purpose

[Jason2tpa]

Skimming through the THT threads I came across a member asking about this small hole located on the lower unit (red arrows pointing). Seeing that thread reminded me to post a question on this forum, asking what this small hole is and what's its function. The engine pictured is a '03 200hp 2 stroke. I have the same hole in the same location, my engine is a '98 S115W.

The member on that forum was asking when filling gear oil, if seeing gear oil exit this hole was something to be concerned about. I actually don't know, because I don't know what this hole is as i mentioned. Can anybody fill me in with info about this hole?

Maybe someone even has a cut-away photo of a model with the same hole so I can visualize whats happening inside the LU (Boscoe??). Thanks.

[Sequoiha]

If the drive shaft seal is leaking oil will come out of that hole, I suspect it's a water drain of sorts for the seal area. It also has a scoop on it, maybe it cools the upper bearing while underway.

[TownsendsFJR1300]

If the drive shaft seal is leaking oil will come out of that hole, I suspect it's a water drain of sorts for the seal area. It also has a scoop on it, maybe it cools the upper bearing while underway.

I suspect your correct. When I did my water pump last, there was a bunch of small debris inside where the seals are (under the wear plate).

And it does drain especially when tilted up...

There's really no other way crap can get in under the WP wear plate.
And I've had the small SS seal spring fail on the top seal-(salt water
with no fresh water there to flush?)

I have NOT noticed a drain hole in there, but makes sense..

Below is a pic of the "seal cover" (under the wear plate). As I flush religiously, regular flushing will NOT get fresh water into that area, thus
the corrosion seen.

Looks like another small spot to put the garden hose to to flush salt water out...

Great question and answer BTW...

[BQUICK]

In regard to that seal....I put a new spring on my seal last time it was apart. Seal didn't seem to be leaking tho. I know not right way but worked for me....

[pstephens46]

Sounds like a pain but I think best practice is to pressure test the lower unit every time the oil is changed. Might take 5 mins total with a Mity Vac.

Anything to help preserve this expensive part...

[TownsendsFJR1300]

In regard to that seal....I put a new spring on my seal last time it was apart. Seal didn't seem to be leaking tho. I know not right way but worked for me....

That's what I'll do next time the spring fails, then pressure test it for confirmation...

(The inner seal spring was fine-not exposed to seawater)...

[Jason2tpa]

Sounds like a pain but I think best practice is to pressure test the lower unit every time the oil is changed. Might take 5 mins total with a Mity Vac.

Anything to help preserve this expensive part...

That's a smart move I need to include. Any idea the amount of pressure to apply, or are you just filling with a small amount of air then watching the needle for a drop in pressure?

[pstephens46]

F150 manual states 10 psi for 10 secs. If it will hold, good to go.
Not a very torturous test by any means...