Gear oil leaking from lower unit drain hole

[CAPTKEV85]

Good evening all. My 1985 mercruiser 260 with alpha 1 drive is getting ready for the season. Now I made a wood stand to store lower unit in my garage which gets down to 50 degrees in winter. When I moved it from the garage I noticed that the drain hole was wet with oil. I drained the gear oil and replaced with new. No milky in old oil. Now I started my boat up ran it and now I noticed oil seeping from drain hole and down the skeg. Now last year I replaced upper water pump housing and impeller and did not see any leaking from there. What is my next step? Split drive? This sucks because I just put a 21.00 dollar bottle of royal purple marine gear oil which now has to be drained.

 

[Grub54891]

Drain the oil in to a clean pan, then run it through a paint filter in to a clean bottle. Now pressure check the unit. In my experience, the shift shaft seal in a likely culprit, easy fix. Now if it isn't that, when assembling the lower to the upper, the upper shaft seal can get damaged pretty easily. Not to bad of a fix either.

 

[CAPTKEV85]

Ok thanks for fast reply. Now I did not split drive this year because no need to. I did notice shaft going into upper housing was dry as a bone. So should be able to rule that out. Hopefully it's shaft seal. Is that an easy fix?

 

[SHickey]

I had the same situation with my old Starcraft American 20 1974 165 hp MC-1 slowly leaking oil from the water weep hole. Bought the shift shaft seal parts, split the drives and replaced the seal and NO more leak. For me it took more time to reassemble the two drives than it took to replace the seal because I don't do it very often.

 

[bruceb58]

When you change your oil do you always replace the gaskets on the fill and level plugs?

 

[Grub54891]

The shift shaft seal is easy, you would need to buy the tool to change it or fabricate your own. Either way its easy.

 

[Newbie@boats]

Is the fiber washer damaged behind the screws?

Did you replace that when you did the service?

For what they cost I usually replace the washers every time I remove the screws for the drain/vent

 

[CAPTKEV85]

Hear is an update... No more leak . The shift shaft seal that threads into drive which is brass was cracked. Also my lower water pump housing was leaking. All fixed now thanks for help.