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Results 1 to 27 of 27
  1. #1

    Default Water in the Lower Unit Gear Oil on Mercury 75hp Outboard (2 stroke 4cyl) Serial# A953769

    I have a Mercury 75hp. I'm new to boats but have some common since. I had a friend do a tune up on a boat that i purchased back in June. During that tune up he replaced the Gear oil in the lower unit. The other day we went to check the levels, just out of curiosity and found a white milky substance. He said that there wasn't any water in it before. Take in consideration that the boat had sat for atleast a year before i purchased it. It runs good and doesn't have any issues going into gear. It appears that water is getting into the lower unit. Of coarse i replaced that gear oil for the time being. I looking for some suggestions on what i should replace to make sure i take care of the problem. Should i just replace the inner & outer oil seal bearing? I inlcuded a link below that shows a diagram of the lower unit. Open for suggestions


    http://www.boats.net/parts/search/Me...%29/parts.html

  2. #2
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    Default Re: Water in the Lower Unit Gear Oil on Mercury 75hp Outboard (2 stroke 4cyl) Serial# A953769

    Install a complete seal kit / o-rings.-----------Including the seal on the shift shaft.-----------Pressure test after completing your work

  3. #3
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    Default Re: Water in the Lower Unit Gear Oil on Mercury 75hp Outboard (2 stroke 4cyl) Serial# A953769

    I tend to take a slightly different approach.

    Milky gear oil does indicate water intrusion. But if you live in a 4 season location (Canada, Northern U.S.) you are almost always going to have some water intrusion. 1/4 of the year the gearcase gets baked in the hot sun (which causes everything to expand - at different rates) and then all winter its subjected to negative temps, contracting everything up. So you will never have a "perfect" seal.

    I would drain your gearcase and install new. Keep some of what you drained in a glass jar for a day or so and see if water actually separates out. If it stays milky but you don't get a layer of water on the bottom, your seals are probably ok. If you see a layer of water then you probably have a real "leak" as opposed to just some seepage due to the expansion/contraction of the case.

    If it's just seepage, then simply keeping the oil changed once a season (and best done just before you winterize) is usually sufficient. If you boat in excess of 100 hours a year, then an oil change mid way through the season is also in order.

    If it is a leak, as Racerone suggests, get a complete seal kit...
    Graham

    A "professional" is someone who gets paid for their work - it doesn't necessarily mean they are good at it :)

  4. #4
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    Default Re: Water in the Lower Unit Gear Oil on Mercury 75hp Outboard (2 stroke 4cyl) Serial# A953769

    Put a seal kit in it --------There should be no water getting in there , none , none whatsoever !!

  5. #5
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    Default Re: Water in the Lower Unit Gear Oil on Mercury 75hp Outboard (2 stroke 4cyl) Serial# A953769

    Hold it! If that motor was running a day or so ago, the oil an be milky in color--it's simply aerated No big deal. Let it sit overnight and try again.

    Jeff

    PS: Of the 13 gazillion drain plugs I've pulled over the last half century, I've always seen water (if present) come out first, followed by what is obviously oil.

  6. #6
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    Default Re: Water in the Lower Unit Gear Oil on Mercury 75hp Outboard (2 stroke 4cyl) Serial# A953769

    I recently bought an 82 merc 50 hp and first thing I did was drain the gear oil and it was milky. I asked prevoius owner if he ever changed it and he said every season and it was always milky but he did admit to never changing the screw gaskets. I changed them and the oil and I just drained the oil after 3 tanks of fuel and no milky now......I will change the fluid again now and the Gaskets ......maybe your problem may be the 50 cent gaskets like mine which weren`t sealing properly.

  7. #7
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    Default Re: Water in the Lower Unit Gear Oil on Mercury 75hp Outboard (2 stroke 4cyl) Serial# A953769

    If there is water in a lower unit there is a seal problem !!!!--------To me it is not acceptable and easily fixed.

  8. #8
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    Default Re: Water in the Lower Unit Gear Oil on Mercury 75hp Outboard (2 stroke 4cyl) Serial# A953769

    IF there is water in there. Milky oil does NOT necessarily mean water is present.

    Jeff

  9. #9
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    Default Re: Water in the Lower Unit Gear Oil on Mercury 75hp Outboard (2 stroke 4cyl) Serial# A953769

    you guys may like to read this article about water in lower ends....... http://www.duckworksmagazine.com/06/...max/index1.htm

    this guy has an interesting take on this problem !!!

  10. #10
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    Default Re: Water in the Lower Unit Gear Oil on Mercury 75hp Outboard (2 stroke 4cyl) Serial# A953769

    I tend to agree with the article, but we are all different and have different opinions about "what is acceptable". I am willing to tolerate some slightly milky gear oil. After all, why bother running GL5 rated oil, which will tolerate some water without foaming and blowing out the seals (whether they are perfect or just a hair leaky) if we are going to rip out and replace seals at any sign of moisture.

    When I first undo the drain screw if the first thing that exits is water, then I will replace a seal. If I just get "milky", I change it and let the stuff I just drained sit for a day or two to settle. If no water appears as a thin layer at the bottom of the jar (which is clearly visible if it's there), then I consider it "normal".

    However, if a definate layer of water is detectable after a couple of days settling, then I would change the seals as well.

    Some water in the lower unit will often do more damage when the motor is sitting in "storage mode" than if you are running it all the time. When it's sitting, water in the case will allow a portion of the gears to rust (where they are sitting in water, at the bottom of the case, since the oil floats on the water) during the months between "boating season".

    That is why I suggest changing gear oil at the end of the season when you (winterize) whether or not you detect any water, milky oil, or all looks fine.
    Graham

    A "professional" is someone who gets paid for their work - it doesn't necessarily mean they are good at it :)

  11. #11

    Default Re: Water in the Lower Unit Gear Oil on Mercury 75hp Outboard (2 stroke 4cyl) Serial# A953769

    Thanks for all the comments. The Gear fluid that came out when i drained it was like a Milk Shake. It was changed about a month ago and the boat has been out on the lake about 5 times in that time frame. Should the fluid get that milky, that quick. I'm not much of a mechanic, but i can do some minor things. A friend and i plan on replacing the seals. Does anybody know if you have to drop the lower unit or if you can get the seals out without removing the prop shaft. My friends pretty good with working on things, but it's been a while since he's done the lower ends. What kind of time frame am i looking at for this project?

  12. #12
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    Default Re: Water in the Lower Unit Gear Oil on Mercury 75hp Outboard (2 stroke 4cyl) Serial# A953769

    You have to drop the lower unit to change seals on the drive shaft and shift shaft.---------------Water is not acceptable in a lower unit.------------------Just price a new lower unit and you will agree.

  13. #13

    Default Re: Water in the Lower Unit Gear Oil on Mercury 75hp Outboard (2 stroke 4cyl) Serial# A953769

    OK, now you guys got me confused. I am hearing "absolutely no water is acceptable" and, "a little milkiness is OK". I am new to boating and have low/moderate mechanic skills (can change water pump, fluids, etc).

    I just changed my lower unit gear oil on my Mercury 60 HP EFI 4 stroke after a whole spring and summer of use in the ocean. Oil looked great at first but then it got very slightly milky. I saved some of this oil and took it to a guy that sold and fixed small boat motors. He said it looked pretty good, but then showed me a neat trick on how to see if it had water in it.


    He dipped a screwdriver tip into the gear oil and then heated the tip of the screwdriver with a cigarette lighter. It sputtered a little bit, which he said indicated water was in there (he said not much, but best to get the seals changed and that it should be done by a boat mechanic since it was much more involved than just changing a water pump). Now from what I am reading here, a small amount of milkiness (water) is somewhat normal and not an issues if I change the gear oil often. Is this correct?

    Also, how much should I expect to pay if I get the seals changed at a boat shop?

  14. #14
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    Default Re: Water in the Lower Unit Gear Oil on Mercury 75hp Outboard (2 stroke 4cyl) Serial# A953769

    Water in a lower unit indicates seal problems !!!----There should be none at all.--------------------If the leak gets " bad " halfway between oil changes then what ????---------------Just check price and availability of a new lower unit, ---------it is severe " sticker shock " for most ordinary working folks.

  15. #15
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    Default Re: Water in the Lower Unit Gear Oil on Mercury 75hp Outboard (2 stroke 4cyl) Serial# A953769

    If the oil looks completely like a milkshake then there is a substantial leak developing and the seals need changing. Before I would reseal after seeing a small amount of creamy marbling from moisture in the oil I take the prop off and check for fishing line stuck under the seals. Don't pull it straight out but rather pull gently on it while turning the prop until the line is removed. Visible WATER should not be in the oil but a little streak or marbling (moisture) like a thread of vanilla ice cream in a bowl of chocolate pudding (moisture) won't kill it. Change the oil and both screw gaskets and run it a short time then recheck it for WATER.

    The last time I saw folks arguing over who was right ended with one getting banned from the site.
    Fix minor things (replace wear items for preventative maintenance.) that cause major problems before they break.

  16. #16
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    Default Re: Water in the Lower Unit Gear Oil on Mercury 75hp Outboard (2 stroke 4cyl) Serial# A953769

    Unless the motor sat for days, the oil will always look like a milkshake (aerated). The best way to be sure is drain the oil into a closed glass container and let it sit for a few days. If water is present, it will all be at the bottom.

    Finally, a little water in there is okay--old outboards always seemed to have some; that's why they used grease instead of oil. Realistically, a lip seals are crappy seals to begin with and are always prone to SOME leakage.

    Jeff
    Last edited by fastjeff; 10-21-2011 at 04:59 PM.

  17. #17
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    Default Re: Water in the Lower Unit Gear Oil on Mercury 75hp Outboard (2 stroke 4cyl) Serial# A953769

    Good seals , properly installed on an outboard do not leak !!

  18. #18

    Default Re: Water in the Lower Unit Gear Oil on Mercury 75hp Outboard (2 stroke 4cyl) Serial# A953769

    Thanks for the replies. It seems that there is at worst a very small amount of water after a full season of boating. I appreciate the input from both sides on this. I will leave things alone and do a gear oil change after I have the boat back in the water for a month or so and see how it looks before I go for the seal replacement. Thanks for the help.

  19. #19
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    Default Re: Water in the Lower Unit Gear Oil on Mercury 75hp Outboard (2 stroke 4cyl) Serial# A953769

    ...take the prop off and check for fishing line stuck under the seals.
    My insurance co. paid $675 to reseal my Mercruiser 175 HP I/O because some dufus cut his fishing line when snagged. I drove over it and about 100 yds. of 10 lb. test line wrapped around the inner spool cutting the double oil seals. The first sign of trouble was a wee amount of line sticking out from under the outer seal.
    Fix minor things (replace wear items for preventative maintenance.) that cause major problems before they break.

  20. #20
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    Default Re: Water in the Lower Unit Gear Oil on Mercury 75hp Outboard (2 stroke 4cyl) Serial# A953769

    ALL lip seals can leak. They are neither permenent or reliable.

    Jeff

  21. #21
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    Default Re: Water in the Lower Unit Gear Oil on Mercury 75hp Outboard (2 stroke 4cyl) Serial# A953769

    I'm very familiar with this problem. To solve it, I change the lube in my L/U every 4 months. (I'm in South Louisiana and get to use my boat at least once a week) As far as I'm concerned its cheap insurance. Only way to be sure is to change it. I have a close friend who was a maintenance supervisor for a large chemical company. That company did research on lube in bearings and found that even a small amount of water in bearings would greatly shorten their life span. (Even measured in parts per million) So I got a pump and use W/M lube and do it when I change my truck oil (also every 4 months). I figure $5 or so is cheap compared to the cost of even a rebuilt L/U. I also pull the prop and check for mono...BF

  22. #22

    Default Re: Water in the Lower Unit Gear Oil on Mercury 75hp Outboard (2 stroke 4cyl) Serial# A953769

    Well, I ran my situation (slight milkiness but no visible water in gear oil) by the mechanic at our local boat shop. He said he has done thousands of lower end gear oil changes and that my situation is perfectly normal. He said if water comes out first, then I need to get the seals looked at, but a slight milkiness is typical from condensation in the upper part of the lower unit and he would actually be more concerned if there was no sign of milkiness since this is the norm.

  23. #23
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    Default Re: Water in the Lower Unit Gear Oil on Mercury 75hp Outboard (2 stroke 4cyl) Serial# A953769

    Lower units are sealed and there should be no water from condensation.------------------------I guess a lot depends on whether you get advice from a mechanic or a " salesman "-------Some shops apparently will say that all is OK with a customers motor .---All the while they are hoping for the sale of a big repair job / new lower unit / or a new motor !!!------------Lip seals are very reliable , they do wear with time and must be replaced when water shows up in a lower unit.

  24. #24

    Default Re: Water in the Lower Unit Gear Oil on Mercury 75hp Outboard (2 stroke 4cyl) Serial# A953769

    I was always under the impression that if it looks milky your screwed, lower units or trailer wheel bearings, you blew a seal. I use merc high performance gear lube in my alpha 1 gen 2, 90 merc outboard and neighbors bravo 3 and it looks almost the same coming out as it did going in.

  25. #25
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    Default Re: Water in the Lower Unit Gear Oil on Mercury 75hp Outboard (2 stroke 4cyl) Serial# A953769

    gl115-------It is obvious that many people / shops / mechanics / salesmen work to different standards.

  26. #26
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    Default Re: Water in the Lower Unit Gear Oil on Mercury 75hp Outboard (2 stroke 4cyl) Serial# A953769

    I would like to think that we are all on the same page about water in the OD oil; not good. Since we all have different eyes and brains our description of what we are seeing may very well be the same in most cases but the words used to describe the condition may mean something totally different to others. Lest we forget, this website serves the entire world; some current members are from the land of Oz, the Emerald Isle, Canada, USA, Central America, Sweden, England, South Africa, New Zealand--I know I have forgotten some.

    Therefore, if I use Mercury OD oil, due to its design it should not foam under extreme pressure. I know the oil does take on a slightly different color/appearence after some use--a bit creamy perhaps like comparing a clear emerald to a cloudy one. If I were to use an automotive generic 80-90 wt. oil in the OD it could foam more than the Merc. oil and look totally different than the Merc oil. I might think it has the appearence of a HEAVY green milkshake due to the millions of micro air bubbles but not infused w/water. A thin milky oil is contaminated w/water--some describe this condition as a mikshake.

    One point that we all have agreed upon is the seal is leaking when water comes out first when draining the OD. This condition will occur when the hot OD oil cools quickly, the seal shrinks and the vacuum created by the condition draws water into the base of the OD. It also occurs when water contaminated oil is allowed to separate over a long period of time such as winter storage. Another point of agreement would be when draining the oil from the OD it comes out quickly w/the appearence of chocolate milk--highly water contaminated. Based upon the different viewpoints one could say that although we are reading different paragraphs we are all on the same page.
    Last edited by guyjg; 10-26-2011 at 07:55 PM. Reason: grammar
    Fix minor things (replace wear items for preventative maintenance.) that cause major problems before they break.

  27. #27
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    Default Re: Water in the Lower Unit Gear Oil on Mercury 75hp Outboard (2 stroke 4cyl) Serial# A953769

    ..."Well, I ran my situation (slight milkiness but no visible water in gear oil) by the mechanic at our local boat shop. He said he has done thousands of lower end gear oil changes and that my situation is perfectly normal. He said if water comes out first, then I need to get the seals looked at, but a slight milkiness is typical from condensation in the upper part of the lower unit and he would actually be more concerned if there was no sign of milkiness since this is the norm. "

    Correct! That man knows his stuff. Can't tell you how many people panic when they see aerated oil.

    Jeff

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