gap in lower unit halves

choochooharley

Petty Officer 2nd Class
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Aug 27, 2008
Messages
172
I bought a aftermarket lower unit and mated it to my old upper. It went together like it was supposed to except when tightened up on the aft end only by the anode tab there is a paper thin gap. It is tight everywhere else includeing at the oil hole between the halves. No Oil is seeping out and no water in the oil (yet). Is this going to cause a huge issue? Any thoughts and opinons welcome.
 

ziggy

Admiral
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Jun 30, 2004
Messages
7,473
Re: gap in lower unit halves

imho, and i'm no pro. but that whole area is normally exposed to water. the only thing that needs a seal is at the quad ring, the gear lub passage between the upper and lower.
that's the way i see it anyways.

bummer it don't quite mate proper though.....
 

choochooharley

Petty Officer 2nd Class
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Aug 27, 2008
Messages
172
Re: gap in lower unit halves

That was my opinion as well.....but I just wanted to get some thoughts.....and yes it is a bummer
 

ziggy

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Re: gap in lower unit halves

maybe a pressure/vac test would be in order to be sure ya got the seal..
 

ziggy

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Re: gap in lower unit halves

look at #8... http://forums.iboats.com/showthread.php?t=288430


once a year,

i usually have been testing at 13 or 14 psi for 24 hrs. turning the drive and prop shaft a time or two during the 24 hrs.

then vac test at 5 hg. same thing. turning the drive and prop shaft a couple times during the test.

after the 24 hrs, it has to be the same pressure/vac ya started with or ya got a leak some where....

i for sure do the test after impeller replacement, which i do every year. some times i'll test it prior to impeller replacement, but not always..
 
Last edited:

choochooharley

Petty Officer 2nd Class
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Aug 27, 2008
Messages
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Re: gap in lower unit halves

Thanks that helps alot and looks simple enough
 

Don S

Honorary Moderator Emeritus
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Aug 31, 2004
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62,321
Re: gap in lower unit halves

I would still be wondering why it didn't fit properly. Was the alignment pin too long on the back, or corrrosion in the hole. You loose support on the back of the drive when it's only touching on one spot. Of course, the pressure would only be in reverse, but still ??????
Maybe even take it back a part and check things with a straight edge.
 

choochooharley

Petty Officer 2nd Class
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Aug 27, 2008
Messages
172
Re: gap in lower unit halves

I wondered if an aligment pin was a hair too long i can take it apart and measure the old pin and the new and test with a straight edge....all of its not a bad idea....
 

ziggy

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Jun 30, 2004
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7,473
Re: gap in lower unit halves

so much for eli whitneys idea of interchagneable parts... :rolleyes: i hate it when that happens..
 

choochooharley

Petty Officer 2nd Class
Joined
Aug 27, 2008
Messages
172
Re: gap in lower unit halves

Im starting to feel like its JC Whitney idea of interchangable parts....lol
 
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