87 Mercury 9.9

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CaptTorS

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May 28, 2013
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I replaced lower unit oil, after seeing oil coming from vent hole, when I drained it about half an ounce of water came out first. I ran it around lake, came back, now the new oil came out off vent hole again. Anyone have a theory as to why? This motor has around 25 hours on it since rebuild. Thanks
 
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carholme

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Sep 4, 2010
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Re: 87 Mercury 9.9

Which are you referring to as the "vent hole"? Is it a an approximately 1/8" hole?

Gerry
 
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CaptTorS

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Messages
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Re: 87 Mercury 9.9

There's a screw in it, it's the smaller on prob around 1/8" , I always thought of it as "vent" hole as opposed to the lower "drain" hole or plug
 
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CaptTorS

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Messages
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Re: 87 Mercury 9.9

No, I have ordered a few of both the drain, and vent seals, when I changed the oil, I used a little sealant from a tube of rubber gasket , to hold until I get seals. Am I calling the correct term as a " vent" hole?
 
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carholme

Rear Admiral
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Sep 4, 2010
Messages
4,845
Re: 87 Mercury 9.9

Yes that is the vent hole which has to be open when you are filling the gearbox from the drain/fill plug on the bottom. You must have good new seals on those screws. Even re-using them a few times can allow water entry into the gearbox. Hopefully, when you get the seals your problem will ge gone.

Gerry
 
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