Chocolate milk in my lower unit.

[mogfisher]

Hey fellas. I have a 80 something Mercury 18 and I love it. It really scoots my 1442 along. Anyway, when doing the yearly lower unit change this fall, the oil came out milky. I know that there are a few ways for water to enter the lower unit, but how do I tell which one has failed? I did an impeller on this motor last year and the boat shop said I should re use the old gasket that sealed the impeller housing to the LU. This goes against my better judgement but I'm new to outboards so I did what they said. You think that could be the source of my water intrusion? I also had a heck of a time getting a prop off this thing. Gave it a few good whacks before deciding I had to cut it off. Maybe I buggered up the seal on the prop shaft? Where should I start? I want to get going on this soon so I don't end up trying to hurry it along once fishing season comes up. Thanks folks!

 

[crazymanme2]

There's a seal under your water pump & behind your prop.There's also a seal for your shift rod.
The only way I know of is presure testing with air.I believe only 4 lbs of air is what's used.
I have included a break down of your lower in the link below.Click on both the gear housing links. You didn't post your serial #'s of your motor so this may not be exactly the same for part #'s but it gives you an idea.

https://www.boats.net/parts/search/Merc2/Mercury/18XD/9378151%20THRU%209507380/GEAR%20HOUSING%20(PROPELLER%20SHAFT)/parts.html

Hope this helps

 

[mogfisher]

That's great info.Thanks. Maybe I'll just do all 3 seals and forget about it. They look cheap enough and would give me some peace of mind. Thanks again!