# Water in lower unit oil



## TClark (Apr 20, 2007)

I have a mercury 9.9 hp 2 stroke and I was draining it today to add new oil.
There was about 1/2 a cup a water came out first.

What caused this? I'm a newbie at this...seals? Which one??

Thanks,
Terry


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## bountyhunter (Apr 28, 2004)

theres more than one seal. one on the upper screw,one on bottom screw. and behind the prop are a couple more. check those o rings [or flat washer] on the screws where you removed to drain oil. pull prop clean junk that can get behind it. your real lucky it didn,t freeze and crack the case.


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## TClark (Apr 20, 2007)

"your real lucky it didn't freeze and crack the case."

Amen to that!! 

I did notice the small screw has a blue washer/seal, but not the large bottom screw.


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## MassillonBuckeye (May 3, 2010)

TClark said:


> "your real lucky it didn't freeze and crack the case."
> 
> Amen to that!!
> 
> I did notice the small screw has a blue washer/seal, but not the large bottom screw.


Thats definitely a problem. Might not be the cause, but that needs a fiber washer as well. Quicksilver sells them in 5-10 packs I believe.


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## bountyhunter (Apr 28, 2004)

change them and in the spring, use your motor a few times then change the oil, IF its milky looking you still have a leak. but it sounds like the fish gods saved your butt this time.


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## sherman51 (Apr 12, 2011)

you could have got some old fishing line in behind the prop and damaged the prop shaft seal. or it could just be worn and letting water in. I would replace both the upper and lower fill screw washers and the prop shaft seal. a little caution can go a long way towards saving your lower unit.

and yes you dodged the bullet this time with all the very cold weather we've had lately. somebody was watching over you for sure.
sherman


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## KaGee (Sep 8, 2006)

Pay a shop to pressure and vacuum test the unit before you do anthing. It's probably just the missing washer.


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## bajuski (Apr 9, 2004)

Make a pressure tester, I made one out of stuff I just had laying around. My leak was small and couldn't find it so I threw the outdrive tester and all in a wheel barrow full of water and found it right away. It was leaking at the water pump!


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## bustedrod (May 13, 2015)

I go with the missing seal


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## TClark (Apr 20, 2007)

Thanks everyone!!! I will search for new screws with the washers/seals.


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## Shortdrift (Apr 5, 2004)

KaGee said:


> Pay a shop to pressure and vacuum test the unit before you do anthing. It's probably just the missing washer.


This is the best piece of advise. Your description of being a newbie would rule out tackling prop seal replacement. You have $3000 of kicker hanging on your boat. Why risk guessing or trial and error. That was a sizeable amount of water in a small amount of lower unit oil. This is the time to get your motor into a QUALIFIED Mercury dealer as it is the slow time of year.


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## bountyhunter (Apr 28, 2004)

shortdrift has a very good point, can,t cost to much and it,ll ease your thoughts of a worse problem.


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## sherman51 (Apr 12, 2011)

I agree with shortdrift and bountyhunter. take it to a pro and let them find and fix the problem.
sherman


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## TClark (Apr 20, 2007)

Would if I could guys. Short on cash like always...I'll probably try and find some new washers, take it out once in spring and see if water got in...if it does, then I'll consider tearing into it.

Worked on all my own cars since I was 16, helped my dad rebuild engines...how hard could it be??


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## bustedrod (May 13, 2015)

well my friend if you can fix a car you can fix an outboard, that's a lot of water I agree , but how long was it before you noticed water, that seal missing on bott screw will leak, I have an old 86 90 hp merc and I check my oil a lot, when it gets dark I change it, if some milky change it. but I would change the seals on the screws , new oil and run it ,, check oil if it has water then a bad seal .. if not then down the road...


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## TClark (Apr 20, 2007)

I agree bustedrod!! Now to figure out how to search for these washers for the screws. ;-)


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## moondog5814 (Apr 8, 2007)

If you work on your own cars and have rebuilt engines, you can handle a prop seal. I would replace it and the washers for your plugs. Then, change the oil......run it , then check for water in oil again. Plus, you have the satisfaction that you did it yourself and saved some money by not taking to a dealer.


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## bustedrod (May 13, 2015)

I live in akron area and there are various boat dealers around they usually have them.


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## sherman51 (Apr 12, 2011)

TClark said:


> I agree bustedrod!! Now to figure out how to search for these washers for the screws. ;-)


you can get the washers at just about any marina. as for changing the prop shaft seal its not that big of a deal. getting the old seal out is the hardest part, but still not hard. I changed my 1st one back when I 1st started boating and everything went smooth as silk. if your mechanically inclined you shouldn't have any problem changing the seal. I used a wooden hammer handle to tap the new seal in place. using wood prevents damage to the new seal. but I would try just replacing the screw seals first. then after using it check for water or milky oil. I would check it for a few trips just to be sure.
Sherman

you can get the screw seals off ebay. but the shipping costs more than the seals, LOL.


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## MassillonBuckeye (May 3, 2010)

http://www.ebay.com/itm/like/162245728617?lpid=82&chn=ps&ul_noapp=true
should be what you need.


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## fastwater (Apr 1, 2014)

TClark said:


> I agree bustedrod!! Now to figure out how to search for these washers for the screws. ;-)


Most all boat dealers will have them. 
The upper fill screw and the lower should have the same style washer. 
You may be able to take your upper washer to NAPA and match it up. 
Or if you have a shop that sells hydraulic parts...fittings seals, etc. most likely will have them.
Just take your old one with you.


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## firemanmike2127 (Mar 17, 2013)

Massillon Buckeye has you headed in the right direction on the proper screw seal, but be sure to monitor the oil quality in the spring. Allow the engine to sit overnight with the engine tilted up about halfway. That way if there's any accumulated water it will have separated & be visible right away when you remove the lower drain screw. Mike


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## TClark (Apr 20, 2007)

Water came out first, then the milky ugly looking oil.
One thought, Rut Roe. Just hope that's all it is. ;-)

Merry Christmas everyone!!


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## DHower08 (Nov 20, 2015)

Terry if you can use just a tiny amount of common sense you can redo that lower unit. Very simple project


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## TClark (Apr 20, 2007)

Hi DHower08, I am seriously thinking about it my friend...got 3+ months till spring, so I got plenty of time, that way I know my butt and motor is covered. ;-)

got the washers today, new seals and impeller shouldn't be that much.

anyone know a dependable place to buy seals, impeller ?
1986 9.9 hp 2 stroke Merc.


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## DHower08 (Nov 20, 2015)

Terry the only guy i trust is up by me in massillon. Long ways away from you. Im thinking about hitting piedmont this weekend. Ice should be off and able to launch on the goat trail


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## DHower08 (Nov 20, 2015)

Terry dont forget to throw a new impeller in that beast while you got it apart


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## fastwater (Apr 1, 2014)

TClark said:


> Hi DHower08, I am seriously thinking about it my friend...got 3+ months till spring, so I got plenty of time, that way I know my butt and motor is covered. ;-)
> 
> got the washers today, new seals and impeller shouldn't be that much.
> 
> ...


Any Merc. dealer close to you should be able to hook you up on seals and impellar. Be on the safe side and take your serial number with you. Get the impellar kit and it will come with everything you need including, shaft seals,gaskets, Orings, a new key for the slotted key way and a few other pieces. None of which are hard at all to replace. You'll have between $35- 45 in the impeller kit. 
And yes...if you pull the lower unit for anything, while your there you may as well put a new impellar in it.


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## TClark (Apr 20, 2007)

Is this what I need? and is this a good price?

http://bpi.ebasicpower.com/shop/ind...fo&cPath=1264_1299_1314_1366&products_id=5524

1986 Merc 9.9 hp 2 stroke
Serial # 0B118918


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## KaGee (Sep 8, 2006)

Don't know if you have the right part or not, but Ebasicpower is a very good source.


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## miked913 (Feb 29, 2008)

Make sure that the washer isn't just stuck in the area where the screw shoulder snugs up. It may be there and you just unscrewed the plug out of it. It's kind of hard to lose them.


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## DHower08 (Nov 20, 2015)

Terry did you fix that beast yet. If you got any questions and still have my number gimme a shout


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## TClark (Apr 20, 2007)

I bought new washers and put em on. Going to take it out a time or two then drain the oil and see if there's water in it again or not. THEN I'll go for the hard fix. ;-)

Thanks everyone for your input and reply's.


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## DHower08 (Nov 20, 2015)

Run that thing in a barrel of water and then check it. No sense in dragging it to the lake when you can do it in your garage


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