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Old 02-13-2012, 02:25 PM   #1
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Default Alpha Gen 2 outdrive; replacing upper gear case oil seals ADVICE

Hello, I have an Alpha Gen II outdrive with about 180 hours on it.

I pressure tested the outdrive (it's off the boat with oil drained, tested at 15 psi) and it definitely had a small leak, hit 12 psi within 3 minutes and 6 psi within 10 minutes. I did notice a bit of water in the oil last summer when I took it off and drained it.

Today I split the gear cases and tested the lower and it holds pressure fine, so figured it is the upper. I then put them back together and tested the outdrive as a whole and could hear air coming from the vertical drive shaft in the open space behind the lower shift shaft where the drive shaft comes out of the upper down into the lower unit. Definitely worse than before. The part number on those seals is #5: 26-66302 ( and consists of two oil to hold the water out and the other to hold the oil in I assume.

I have the merc manual #14 (page 3A-14) that describes how to get to these seals and change doesn't look too bad but I would need the bearing retainer wrench p/n 91-17256 ($60-80) in order to pull the u-joint assembly out and gain access from the top for the two oil seals. The seals only cost around $8. I've never pulled apart an upper before but am a confident in my abilities to figure things out.

At this point it's a decision to pay for the labor of doing this or pay for the parts and tool and just do it myself. I'm leaning towards just doing it myself but figured I would take a poll from the forum.

My questions for the forum are:

-has anybody done this job and if so how challenging was it?
-Is the retainer wrench the only specialty tool i'll need?

Any opinion/advice is welcome....
battleaxe99 is offline   Reply With Quote
Old 02-13-2012, 05:58 PM   #2
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Lot's of good sterndrive info there.
Byter is offline   Reply With Quote
Old 02-14-2012, 11:03 AM   #3
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Originally Posted by Byter View Post

Thanks for the links! Lots of good info.
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Old 02-14-2012, 12:43 PM   #4
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I have the spanner wrench and have changed u joints but never pulled the uppper bearings or gears. with the spanner wrench I just beat it with a rubber hammer to get the nut off then hooked a torque wrench to it to get it back together. pulling upper drive shaft and bearing may take some doing though. You get a price to have it done yet? has good mercruser forum and I spent a lot of time there when I had mine
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