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Lower unit seal kits

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pbrown

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"I have lower unit oil coming

"I have lower unit oil coming from the prop on my 1989 4cyl 40hp merc. I assume that I need to change a seal. After hearing the hourly rates of a dealer I decided to look into doing this myself. So I have three questions:

1)Is the Seloc "Mercury outboard repair manual" an appropriate reference for a moderately skilled do-it-yourselfer?

2)What seal's do I need? Do get a 50$ kit with all of the o-rings, gaskets, and the seals. or should I figure out which seal I need and get it? I'm cheep but not super cheep. And I realize that often it is better to just replace things while you have it apart.

3)Are there any special tools I need. Someone mentioned a tricky retaining ring?"
 
oil dripping from the lower un

oil dripping from the lower unit/prop is normal. Any un-burnt 2 cycle mix/exhaust comes out the prop. Engines that idle or troll have excessive build up of gunk that doesn't have the chance to burn off during normal use. Now if it is clear oil and smells like rotton eggs then buy the whole kit and take just the lower unit it to a shop.
 
"JB I'm intrigued about th

"JB I'm intrigued about the extra oil buildup because I did troll for a few hours the day before I noticed the puddle of oil in the driveway. To be honest I never actually looked at the lower unit oil, I just assumed that's what the puddle was. I'm going to let a little lower unit oil out to check for signs of a leak. Thanks for your help."
 
"You should drain and change t

"You should drain and change the oil in the lower. A bad seal will let water in or oil out. Better 20 bucks now than 200 later. If it looks ok then let it go. Lots of people put a chunk of cardboard under the lower after running. Either way give it the sniff test, rotton eggs and its bad."
 
Gear oil brand new smells bad!

Gear oil brand new smells bad! Pressure test the lower to determine leaks. No need to guess here at all.
 
"Pressure testing sounds like

"Pressure testing sounds like a good idea. Other than scrapping a lower unit oil pump does anyone have any suggestions for a fitting to fill the lower unit with air. That is, what size are the threads in the drain/fill holes on an '89 Mercury?"
 
She failed the pressure test..

She failed the pressure test... But I cant get a good answer on what seal kit this my motor needs. I have a 1989 4cyl 40 hp mercury. The serial number is M104820. Everytime I call to order the seal kit I get a different suggestion on which kit I need.
 
"Peter, there is two different

"Peter, there is two different seal kits for your motor, at least that's what I see looking at the Merc parts list.

They have a gear housing seal kit, part number 2697831A1 which includes all the gaskets/seals needed for the waterpump base etc plus the propshaft seals etc. The number may vary slightly (as in ....31A1 or 31A9 etc but would all be the same) - it sells for about 80 bucks.

The waterpump repair kit, 46-77177A3 (or slight variations) would only include the seals below the waterpump, plus the waterpump components.

If you have a leak in the gearcase (somewhere) I would assume you would be looking for the first kit I mentioned...."
 
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