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upper stern drive seal merc

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bob harper

New member
Have a merc 3 litre alpha one. Removed engine to rebuild. When engine was removed my mechanic saw gear oil in the bellows. He replaced the upper seal in the drive. This spring when new engine was installed, found gear oil in the bilge. Removed the stern drive again and replaced with another seal. Unit still leaked, swapped out the drive shafts and universal joints from a known V6 engine but swapped all the gears. Reassembled and put back together. Unit still seems to be leaking. Has anyone else experience this or have any knowledge of what else to do?
 
assuming the new donor parts were serviceable...and the proper procedures were used, it shouldn't be leaking....are you positive its gear oil in the bilge?
 
Sorry. Missed where you said the oil was inside the bellows.

A seal can wear a groove in the shaft. When the new seal is installed, the new one will run in that groove and leak as well. A solution to that is to space the seal away from the groove a 1/16 inch or so with a plastic or metal spacer.

Perhaps this is what's needed here?

Jeff
 
thanks for the feedback to all that reached out with advice i just pulled the sterndrive and no gear oil seems the swap we made did the trick have to assume it was agroove in the shaft or warped yolk. thanks again for all the feedback. very hel
 
glad to hear that....and keep the outdrive down whenever you leave the boat, especially on the trailer, will let the bellows last a long time....
 
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