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Results 1 to 11 of 11
  1. #1

    Default Lower unit - how to take apart

    Hi there,
    I have a 3.9 Mercury outboard, about a 1968? I want remove the lower unit but only can get it apart about 1 inch? What else do I need to do to remove it completely??

  2. #2
    Join Date
    May 2010
    Location
    Northwest Wisconsin
    Posts
    13

    Default Re: Lower unit - how to take apart

    That one is much older than my 6hp and 15hp mercs, but I was having the same trouble. On mine, I had to release the shift shaft from up inside the housing before the lower unit would drop out. I had a thread on here not too long ago and it was answered very nicely by some small outboard geniuses (this site rocks), and there are some pictures about it on that thread. Look for "dropping lower unit on 15 hp" in the title. But, I don't know for sure as I haven't really worked on a merc of that vintage, so hopefully somebody knowledgeable can chime in. But this might help...

  3. #3

    Default Re: Lower unit - how to take apart

    Can't see any screw, looks like the shaft is pressed onto the gear on the top of the shifter - The pics look different than what I have here mlmarkee, thanks though, hope someone else out there has taken one of these old timers apart!

  4. #4
    Join Date
    May 2010
    Location
    Ottawa, Canada
    Posts
    92

    Default Re: Lower unit - how to take apart

    halfway up the housing on the outside I think there is a plastic block below the reverse lock dogs that you have to remove, that is going back a ways now - LOL. I have a couple of those at the shop and will take a look today and post back.
    Regards,

    Dave Scott
    Aim Outboards and Machine
    613-831-1246

  5. #5

    Default Re: Lower unit - how to take apart

    Hi Dave
    Would really appreciate any help you can give me -thanks so much!

  6. #6
    Join Date
    May 2010
    Location
    Ottawa, Canada
    Posts
    92

    Default Re: Lower unit - how to take apart

    I looked at the little 4 I have in the shed, just quickly I was wrong there is no reverse lock stop on those. It is all in the housing like the 7.5,9.8 and 20's of that era. That should just pull out, there is a connection half way up the mid looking at the pictures. I have to get that little 4 running anyhow, so if I have time today I will pull mine off and check the impeller and let you know.

    rgds,

    Dave
    Regards,

    Dave Scott
    Aim Outboards and Machine
    613-831-1246

  7. #7
    Join Date
    Sep 2003
    Location
    New Tripoli, PA, USA!
    Posts
    12,647

    Default Re: Lower unit - how to take apart

    If that's like a 6 and 7.5 hp, the nut holding the prop shaft in turns clockwise to remove it.

    Jeff

  8. #8
    Join Date
    May 2010
    Location
    Ottawa, Canada
    Posts
    92

    Default Re: Lower unit - how to take apart

    I checked and it should just slide off you are likely stuck on the upper shift shaft by upper I mean where the lower and upper meet in the d/s housing. I pulled mine off with the 2 nuts and a little wiggling and it had been on there a while try wiggling the shifter at the same time, I also checked the service manual and the removal paragraph for all model from 20 down is just the two nuts and remove the lower the 20 has one more step. They go on at a fixed angle make sure you have the lower unit with that angle.

    It sounds like it just being stubborn on ya, but Mercs never do that. LOL
    Regards,

    Dave Scott
    Aim Outboards and Machine
    613-831-1246

  9. #9

    Default Re: Lower unit - how to take apart

    the bottom gear case will not come apart - what seems to holding it is the shifter rod, it is not disconnecting - does it come out with the bottom gear case or do I have to disconnect up above on the shift lever swivel gear? Thanks!! I can get it apart about an inch and that is it, the shifter rod seems to be holding it - do I have to take the propeller and gear out below or do I have to disassemble the power head to get at the shifter gear

  10. #10
    Join Date
    Dec 2008
    Location
    Posts
    149

    Default Re: Lower unit - how to take apart

    Does the power head have to come off this model to release the shifter rod if you move the lower in and out the inch your playing with does the shift rod move as well?

  11. #11

    Default Re: Lower unit - how to take apart

    no, it slides up and down on the shift rod! ahaha ready to burn it!@

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