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  1. #1
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    Default 1972 4 HP Evinrude water in lower unit


    I have a 1972 4HP Yachtwin that runs fine but I just dropped the lower unit oil and it's got water intrusion ( milky ).

    The model is: 4236S-E02002

    The (2) lower unit drain
    plugs each had plastic 'washer / gaskets' but truthfully I can't see how the plastic would keep water out. I am going to R/R them.

    My questions:


    • I'd like to flush the lower unit out so all the water and water-laden oil is removed. How can I do this ?
    • I have a pressure and vacuum tester - what PSI should I pump to ?


    Before I ask about a potential lower unit seal project, I'll check these things first.

    Thanks !

  2. #2
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    Sep 2010
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    Default Re: 1972 4 HP Evinrude water in lower unit

    Plastic washers have been used on those screws for at least 50 years or more.----Why do you say they are " no good "

  3. #3
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    Default Re: 1972 4 HP Evinrude water in lower unit

    After looking for the washers online, I realize that you're right - they are all plastic.

    Mine are bent in a bit, I guess how they would seat in the drain hole, but look OK. I'm hoping they weren't holding a seal ( that'd be the easy fix ). The alternative is to rip an old lower unit apart to replace the seals - not a fun or easy task due to the age of the motor ( frozen, corroded parts )...

  4. #4
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    3,675

    Default Re: 1972 4 HP Evinrude water in lower unit

    Use ATF to flush it out and get some new 311598 washers for the plugs.

  5. #5
    Join Date
    May 2014
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    Reno
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    252

    Default Re: 1972 4 HP Evinrude water in lower unit

    Pressure test it at 6lbs and again at 15lbs. When you drop the lower, 409 sprayed onto likely sources will show you the leak,or submerge the entire unit in water under slight pressure.
    84 Beachcraft 3.8 229cid 6681735 R drive6683545

  6. #6
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    Default Re: 1972 4 HP Evinrude water in lower unit

    Pressure tested to 15 - no leaks. Kept pressure on for 5 minutes. I'm going to clean the gear housing out with ATF and replace the washers...

  7. #7
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    Default Re: 1972 4 HP Evinrude water in lower unit

    Also test it at low pressure,it can leak for one test and not the other.
    84 Beachcraft 3.8 229cid 6681735 R drive6683545

  8. #8
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    ontario
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    Default Re: 1972 4 HP Evinrude water in lower unit

    On a 45 year old motor it is a good idea to install new seals.----Easy to do.

  9. #9
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    Default Re: 1972 4 HP Evinrude water in lower unit

    I tested at 5 psi and then 10 and then 15.

    I would like to change the seals as preventive maintenance - I have no idea when or if they ever were done. However, when I first got this motor with my boat, as a maintenance thing I tried to to R/R the impeller. What a nightmare ! The bolts to remove the lower unit were all frozen - and there was NO WAY to get them off without them snapping. I had to buy a used intermediary housing. Another instance, when I removed the exhaust plate, one of the nuts snapped in the block. Luckily, it was an accessible one and I drilled and tapped new threads.

    FYI - its a salt water engine.

    What is entailed in replacing the seals ?

    Looks like the drive comes off, you remove the impeller housing and under it is a oil retainer.

    On the other end, the prop side, an oil retainer seal is mounted in the gear case head, the gear case head has to come off and an o ring has to be replaced.

    What are the pitfalls ? How do you remove the (2) oil retainers without galling the housing ?

    It's kind of a Catch 22 -

    Thanks.

  10. #10
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    Default Re: 1972 4 HP Evinrude water in lower unit

    UPDATE - I just re-tested pressure at 5, 10, 15 in a large pail of sudsy water; pressure steady, and no bubbles.

    ' If it ain't broke, don't fix it ' is my mantra on this one. If I get water in it again - I'll change the seals. This motor does not get used much each season - if at all - it's a holy sh*t the wind died... motor. This year I did use it for (5) hours straight - more than it's been used in 15 years combined...

    Thanks for the help though.

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