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Mercury Mariner 9.9 Water in Lower Unit Oil

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Yinzerofthree

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Hello everyone! Thanks in advance for reading! I am the proud owner of a Mercury Mariner 9.9hp motor. Motor has always run well for me (knock on wood) since I bought it four years ago. The owner I bought it from knew little about the motor. So I was hoping the helpful people on this forum may be able to help me with a few things. When I took the motor off to bring into the basement for winterization I noticed a lot of water in the lower unit oil when I drained it.
1. Would anyone be able to identfy the model year of this engine? The I attached pictutes of the paint scheme and the made in Japan stamps as well as some other stamps from the inside of the engine. I am happy to provide any more pictures people would need. There is no serial plate on the engine, or any serial number I can locate. I would add I bought a water pump from this site ([FONT=&quot]18-3148 - Water Pump Kit 46-84277T) which fit like a glove if that offers any more insight.[/FONT]
[FONT=&quot]2. Would anyone have any thoughts on what is causing the water in the lower unit. I had the water pump changed by a local memeber of my antique motor club last year, and the impeller is pumping water out the pee hole stongly. I ordered new 3/16 lower unit oil screwss this fall and they did not fit in the screw holes. Does anyone know what size lower unit screws fit this model? The crushable washers look a bit worn and I would like to replace[/FONT]
[FONT=&quot]3. I pulled off the prop and did not notice any signicant issues or wear in any of the seals, nor did I see any fishing line on the prop.[/FONT]
So thanks for reading, and I would love to hear any insight anyone has!!
 

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haventaclue said:
The screws are metric. And are basically the same from '78 through to '86. Mariner 9.9C HP Outboard Motor Parts by Serial Number Range (marineengine.com)
Click to expand...

Everyone,
Thank you all for taking the time to make insightful replies. I am an extreme novice when it comes to anything mechanical, but I have a real desire to learn. So, I have a couple follow-up questions, and sorry if some of these are basic, but I am not intimately familiar with the jargon

Haventaclue - That would make sense that they are metric given the engines Japanese origins. Not really sure why I hadn't thought of that yet.... Am

Racerone - when you reference a seal kit, could you elaborate on that a bit? Would that be a kit that replaces some of the seals shown in this diagram? Mariner 9.9C HP Gear Housing Assembly Parts (marineengine.com). Is this different than the water pump repair kit?

FaztBullet - Shift boot, I am unfamiliar with this part. Where would that part be on the engine? Or do you know what diagram I should look at to locate this part?

Again, thanks so much for taking the time to reply, it is very much appreciated! I am learning a lot trying to address this myself!
 
You may find that an early 1980's YAMAHA 9.9 HP is the same.-----Seal kit may not be listed everywhere.----Consult your local Yamaha or Mercury dealer for good help !
 
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