Lower unit question

unbtabl

Seaman
Joined
Jun 3, 2016
Messages
50
When I went to change the lower unit fluid, I noticed that neither of the screws (top or bottom) had o-rings or washers on them. They weren't stuck in the unit either. Is this correct?
 

jbuote

Lieutenant Junior Grade
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Aug 17, 2016
Messages
1,001
Unlikely that's correct..
Not a pro, but as far as I know, there should be o-ring or washers there..

What drive unit do you have?
The experts will be able to tell you for sure if you provide that...
 

Bondo

Moderator
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Apr 17, 2002
Messages
70,468
Ayuh,.... Merc uses grey hard paper washers as gaskets,......

Yer supposed to replace after each use, though I closely inspect what's there, 'n replace when I see reason too,......

Many times they get stuck in the housin' side, 'n are the same color as the castin',....

If ya scratch it with a screrwdriver checkin' it, ya oughta replace it,....
 

dubs283

Vice Admiral
Joined
Jul 27, 2005
Messages
5,058
They weren't stuck in the unit either.

Stuck? Do you mean tight?

Either way, yes you need ONE gasket per plug upper and lower (two total) and plugs tightened with a suitable flat blade driver (wide blade) by hand

Can't tell you how may times Ive seen drain plug gaskets doubled and even tripled up, sure to cause leaks.

Fill drive from the bottom, up to vent hole in top with high perf or suitable grade gear lube and top off monitor if equipped

And as Bondo says, definitely check for remnants of old gaskets in shouldered portion of plug holes, I use a bent pick, works awesome...
 

alldodge

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Mar 8, 2009
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40,582
Depending on the year the newer ones went to Yellow gaskets, part rubber
 

alldodge

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Mar 8, 2009
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40,582
Never had one leak

But for that matter never had the paper ones leak either

Oh and they also have blue ones (also paper)
 
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