Summer Project - 50hp Merc 2 stroke

Discussion in 'Outboard Maintenance' started by devinmurray99, May 11, 2010.

  1. devinmurray99

    devinmurray99 Well-Known Member

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    For my summer project I just purchased a blown 1999 50hp 2-stroke Mercury for $650 this weekend.  I'm not really sure I know what I am getting myself in to but I am going to try to rebuild it myself and use it on a jonboat I have.  I stopped and got myself a shop manual (Clymer) and began studying it.  Along with diagrams for Merc parts express I think I can do this.  I have documented everything I have done so far with photos and I will post if anyone is interested.

    So during the past 3 nights I was able to remove the lower unit without any issues.  I am having difficulty removing the powerhead though.  I removed all the electrical, shift and throttle cables, and the 6 #10 x 110 screws from the driveshaft housing but it seems the powerhead is still stuck.  I used a small pry bar and I was able to partially break the seal on the port side but not on the starboard.  Clymer mentions no other bolts (so I'm getting skeptical of how good the $38 manual really is).  However Merc parts express shows a mount (P/N 8M0021334) with a #12 screw (P/N 8M0000520) above the adapter plate. 

    Does anyone know if I need to remove this screw and mount combo to get the powerhead off  - OR - do I need to get the help of a hoist and then start more agressive prying? I don't want to pry too hard and damage the powerhead or adapter plate. Dang I would really hate to call a professional this early in the game.  Thanks in advance for any help.

    :-/
     
  2. Brett

    Brett > PRO STAFF <

    The only shop manual worth having is the OEM manual.
    More information, specialty tools, better pictures and specifications.
    Engine specific information, clear step by step descriptions of the process.
    Clymer, Chilton, Seloc....seem to be much more generic manuals.
    Multiple engine models covered with less accurate descriptions.
     

  3. aflatsnut

    aflatsnut I Love microskiff.com!

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    X2

    I found my Yam manual on CD on Ebay real cheap. It bailed me out many times. You get what you pay for.

    Bob
     
  4. devinmurray99

    devinmurray99 Well-Known Member

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    Gosh I never even thought of it but I would prefer a CD anyhow. Thanks for the tip.
     
  5. aflatsnut

    aflatsnut I Love microskiff.com!

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    Just noticed you're in Melb, I'm an old retired f#rt in Palm Bay. If you need a few pointers I'll try to help. I'm not a Mechanic but I rebuilt my Yam, 3 pistons, new reeds about 3 yrs ago and it's still running strong!
     
  6. FlatCat

    FlatCat Well-Known Member

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    Never use a pry bar on aluminum surfaces. Soaking the sealed surfaces with wd40/etc will help penetrate the seal. Tapping with a rubber or cloth covered hammer will also help break any seal that is not mechanically fastened.
    If you scarred the surface prying, have it milled flat before re assembly....also make sure you use an oem gasket kit. I'd avoid hi temp silicone sealants, etc when it comes to marine powerheads.
     
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