Aluminum corrosion in Alpha One Gen 2 transom plate/

[cdawg]

Before I start tearing everything apart I hope someone can give me some idea of what I am looking at. I'm sure I am not the first one to experience this. I'm dealing with a 1997 Mercruiser 5.7 on an Alpha One Gen 2. Water is gushing in through this hole. I am on trailer now. No problem when running engine on mufflers. You can see the entire plate is corroded. Of course I could fill the hole with 5200 which will stop the leak quickly but the rest of the plate will rot through quickly also. I am sure the outdrive needs to come off but then what? Any help will be appreciated. Thank you.

 

[Bt Doctur]

replace the transom outer housing http://www.boatfix.com/merc/Servmanl/14/14cover.pdf complete manual, if it dosent work the second is the transom section
http://www.boatfix.com/merc/Servmanl/14/14b4.pdf

 

[achris]

I've never seen a corrssion hole there, and there's nothing that should be bolted through there. The only explanation I can come up with is that someone dropped something steel or stainless steel on it and the galvanic cell formed.

Pull the drive, pull the engine, disconnect steering and trim pump hoses. Remove the inner transom plate securing nuts, pull the inner transom plate. Then push the gimbal housing out. You may be able to clean it up enough for a welder to seal it up. If not, it's a new gimbal housing I'm afraid.

Chris.....

 

[cdawg]

replace the transom outer housing http://www.boatfix.com/merc/Servmanl/14/14cover.pdf complete manual, if it dosent work the second is the transom section
http://www.boatfix.com/merc/Servmanl/14/14b4.pdf

Bt Doctur, So you are saying you don't think I should need to pull the engine to get this? That would sure make it a lot easier.

 

[cdawg]

I've never seen a corrssion hole there, and there's nothing that should be bolted through there. The only explanation I can come up with is that someone dropped something steel or stainless steel on it and the galvanic cell formed.

Pull the drive, pull the engine, disconnect steering and trim pump hoses. Remove the inner transom plate securing nuts, pull the inner transom plate. Then push the gimbal housing out. You may be able to clean it up enough for a welder to seal it up. If not, it's a new gimbal housing I'm afraid.

Chris.....

Thanks Chris, A used gimbal housing isn't the worst. It is a big job pulling the engine and stern.

 

[achris]

Drive, 15 minutes. Engine, 2 or 3 hours if you haven't done it before....

I've had my engine out and back in, twice in one day. Another story. :facepalm:

Chris.....

 

[achris]

Bt Doctur, So you are saying you don't think I should need to pull the engine to get this? That would sure make it a lot easier.

Can't replace the gimbal housing (outer) without removing the nuts holding it to the inner transom plate. And you can't get to some of those nuts with the engine in place. You also need to remove the exhaust Y-pipe, and you definitely can't do that without pulling the engine.

Chris.........

 

[cdawg]

Thanks,Chris. I've got it. Is there anything you would recommend I be looking for as a cause of this corrosion so it doesn't ruin my new gimbal housing?

 

[hnt]

Years ago I bought a 23" Chris Craft Scorpion that had been sitting at a local marina, I replaced the interior, painted the entire boat and got the Mercruiser 260 purring like a kitten on the trailer. When I finally put it in the water it almost sank at the launch ramp. There was a large hole in the transom assembly from corrosion caused by severe stray voltage at the marina the boat was stored at years earlier. You should be able to find a used transom assembly without too much trouble. Pulling the motor and drive is not that hard and can actually be fun, but not so much fun that you would want to do it again.......Make sure you find the cause of the corrosion.

 

[Luv2fish36]

Looks like Your steering pin seal is done. It's a pretty bad design to begin with and the maintenance free design has made it worse with the Alpha. They used to be greasable along with hinge pins and the G bearing. It's the steel pin that gets pitted out over time, water gets in behind the seal and game over. The seacore bravo's are offered with the stainless steel pin so they last a bit longer. I would just get a new transom assembly. Yes there expensive but you get a fresh start with everything, bellows, trim rams, shift cable, gimble gearing, senders etc..... with that much water coming in I would take a good look at your starter, oil pan, oil senders, pulleys. Hopefully they're not all rusted out.

you might consider rebuilding your transom assembly but I'm gonna guess with that much corrosion it wouldn't hold a new seal anyways.

 

[achris]

The steering swivel is the same, Alpha or Bravo, so you could use the SeaCore stainless one in an Alpha One Gen II gimbal ring.

Part number is 866718A01, SHAFT ASSEMBLY.

Chris.........