Help with lower shift shaft bushing - Alpha

[Fishermark]

Long story short... I replaced the impeller in my Alpha outdrive (1st gen). The gear oil looked fine - a little dark, but no water in the oil. After replacing the impeller I put everything back together and pressure tested it. Would not hold pressure. Sprayed the various shafts with soapy water while it was still together. No bubbles.

Split the lower unit back off and held my finger over the oil hole and checked it again. This time I see bubbles coming out from around the lower shift shaft. No problem - buy a new bushing and install it. Still bubbles coming out - even worse in fact.

The shaft looks brand new - no scoring, etc. There's really no way to install the bushing wrong. Is it possible (or common) to get a bushing with a bad seal? Is there any other possibility I am missing?

I joked with the parts guy at the marina that their prices were so good. (The bushing cost me half of a price I could find online). He laughed and said they do not move many Mercruiser parts. (Most boats here in SW Florida are outboards).

Thoughts?

 

[Rick Stephens]

I'd replace the seal again. If the shaft is good, the seal has to have a crack in it.

 

[achris]

What pressure are your using? That particular seal is only a single, and designed to keep water out, so internal pressure will open it. I usually only replace that one of it leaks below about 5psi.

Chris...

 

[Fishermark]

Chris, I was putting in 10 lbs. I seem to remember that the unit needed to hold 10 lbs. It leaks out at around 5 or 6 lbs

 

[Fishermark]

Chris, now I'm confused. In the stickies at the top of the page there is a post on pressure testing the drives. You and DonS (God rest his soul!) both mention running the pressure up to 10 - 15 lbs. Now you're saying if it holds around 5 it is good.

Now in THIS instance, with the new bushing/seal in place it starts leaking as soon as I start pressurizing it. Within a pound or so, so I am going to work on the assumption that I received a bad bushing seal. But going forward, shouldn't it hold 10 lbs ?

 

[achris]

New seal should be around 12-15, yes. Once it's a couple of years old, 5 becomes acceptable.

If the new one is leaking immediately, it's faulty, take it back and get a new one.

Chris.....

 

[Fishermark]

Just a quick update to finalize this - I replaced the new bushing with a another new one and it works perfectly. I just had the misfortune to get a bad one! Just a good reminder it is always a good practice to test things even after installing new parts.

 

[cchamp]

Thanks for this! I'm about to do this repair this weekend and extra info is always helpful.