When I pulled the sterndrive today, the whole u joint was rusted. I think I forgot the Oring. Please Read.

1985 Century Mustang

1985 Century Mustang

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Ughhh, When I pulled the sterndrive off today the whole u joint assembly was rusted as shown in photo. It was fine last year, but I believe I forgot to put the large Oring in for the water feed, as (shown in photo below circled in yellow). Could this have been the main culprit? I'm thinking that it was the issue. Just asking if there's another way water could have gotten into it causing this.

Also if I clean up and grease the u joint shaft would it be salvageable, or do I need to fully replace it. It was brand new last year... Your thoughts.

1985 Mercruiser Alpha One Gen One Lower Unit.

20250611_123308.jpgScreenshot_20250611_125503_Chrome.jpg
 
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1985 Century Mustang

1985 Century Mustang

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It wasn't the Oring i found it Laying on the ground. What else would cause the water to get in. Maybe the drive shaft seal in the upper part of the sterndrive?
 
Bondo

Bondo

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Ayuh,.... was the big square o-ring in-place where the bellows starts,..??
 
1985 Century Mustang

1985 Century Mustang

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Bondo said:
Ayuh,.... was the big square o-ring in-place where the bellows starts,..??
Click to expand...

Do you mean the thicker Ring at the beginning of the bellows? If so yes it was fine and in tact. I'm assessing the upper and lower shaft seals after I remove the upper gears... If these seals are bad would that cause water to get to the u joint?
 
1985 Century Mustang

1985 Century Mustang

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If the upper and lower shaft seals are bad would that cause water to get into the bellows on the upper unit.
 
P

Pmt133

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1985 Century Mustang said:
If the upper and lower shaft seals are bad would that cause water to get into the bellows on the upper unit.
Click to expand...
On mine when they failed, it was enough to force water up through the shift cable onto the valve cover and into the bilge when pressurized by the exhaust passthrough... so I'd say yes....
 
1985 Century Mustang

1985 Century Mustang

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I removed the upper main gear from the sterndrive and noticed that the seal this sits in was bad, it appears to be compromised by water. The gear itself had rust on the bottom, shown in photo.
20250611_173031.jpg
 
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