Quick Question with lower unit seeping please

dezmond

Senior Chief Petty Officer
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Jul 21, 2010
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Hey Everyone!!!

Getting ready to start to work on the boat this weekend and when I brought it inside at my work I noticed a small little hole in the lower unit on the side and it is seeping out oil. Any ideas why?? I am planning on pulling the lower unit and replacing the water pump etc. tomorrow.

Hope someone can help me out. Here are some pics for ya.



 

alldodge

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Either metal fatigue or corrosion, but think you may need a lower housing. It is in an area where repairs could be done, just need to tear it done to find out.

Either that or replace it
 

dezmond

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Jul 21, 2010
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Well I am pulling it off tomorrow morning so I guess that would be a good time to check it over. If I sand it all down and clean it up, should jb weld be ok to use? Or any other suggestions? I guess this is a good reason to put some shiny new paint on it as well :). Let's hope it isn't too bad.
 

alldodge

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IMO I would not JB weld, if it is totally disassembled, then have it welded up. If its prepped correctly you could JB it, and it might hold, guess if it fails then your replacing the drive anyway
 

dezmond

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Jul 21, 2010
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Hard part will be to find someone to weld it on a weekend :( guess I will see what I can do. I do agree it should be welded. Used lower units are $700-1200 around here. Kinda pricy.
 

bruceb58

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Mar 5, 2006
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Isn't that hole supposed to be there? That's a cavity drain on most drives..I am not as familiar with Mercs. If it's a cavity drain, you have a seal that is leaking.
 
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Fun Times

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Isn't that hole supposed to be there? That's a cavity drain on most drives...
Yes that's the water drain cavity to self drain for winter. Need to ensure that hole is clear of debris during winter so you won't crack the housing....See image D on page 1 - 7, http://www.boatinfo.no/lib/mercruiser/manuals/mercruiser4.html#/14

A seal (possibly shift seals) is leaking and allowing the oil get into the cavity. You may find it when pull the housing off but when you do pull the housing, try to quickly see where the fresh spilled oil vs the old oil flow is running/leaking into the water passage cavity.
 

achris

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Just check that green stuff in the drain hole. Is it oil or engine coolant (if you have closed cooling)? If it's oil, then your shift shaft seal or top box lower seals are leaking. If it's engine coolant, and you have closed cooling, then pressure test the cooling system. Or if it's coolant and you're one of the 'run anti-freeze through, even though it's a total waste of time and money' crew, that would explain it.

Chris.....
 

Bondo

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Ayuh,.... I Agree, the hole is a drain hole, Don't plug it, 'n it appears to be antifreeze green, not gear oil green,....
 

dezmond

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Jul 21, 2010
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760
Just antifreeze left over from when they winterized the boat... No problems there at all :) Got the waterpump kit and the one seal that goes up in the upper part of the drive yesterday and was a really easy job to do. She is pumping out water really nice again :)

Thanks for the advice everyone :) Made the job a lot easier!!!

Dezi
 
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