Just blew my lower cylinder

Discussion in 'Outboard Maintenance' started by Rookiemistake, Oct 30, 2013.

  1. Rookiemistake

    Rookiemistake Well-Known Member

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    So i guess I blew a cylinder in my 2005 merc 25hp.i was running back to the dock and she locked up from full speed to nada in a few seconds.i wasnt able to pull the rope at all.....mechanic says its getting like 50 psi in the lower cylinder. Water pump was working when i started it that day. Oil has always been mixed at 50:1. What could have caused this?i guess im screwed into parting this out....any guesses would be great! Also whats worth trying to part out or just try to sell as a whole?thanks Rob
     
  2. cutrunner

    cutrunner Cert. Yamaha technician

    There actually is no "cylinder head" on a 25 merc.
    But yes, you blowed it up.
    Either it overheated and you didn't notice, or it was its time and it let loose
     

  3. Rookiemistake

    Rookiemistake Well-Known Member

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    Thanks , there really isnt any way of telling if its overheating.or is there?so i guess its only worth parting out.
     
  4. cutrunner

    cutrunner Cert. Yamaha technician

    Yea you can tell but the only way to do that is tear it apart and inspect
     
  5. cutrunner

    cutrunner Cert. Yamaha technician

    I'm not a merc guy so I'm not sure but if it has sleeves it can probably be bored out and rebuilt.
    If its got chrome plasma cylinders it an anchor
     
  6. Rookiemistake

    Rookiemistake Well-Known Member

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    Hopefully someone will chime in.thanks
     
  7. Dillusion

    Dillusion devilray snob

    There is a .030 piston kit you can get, I think boats.net has it.

    Be prepared to spend ~$800 +- on the rebuild unless you do it yourself though.

    I would just get a brand new powerhead off ebay:

    like this:

    http://www.ebay.com/itm/20HP-25HP-MERCURY-MARINER-POWERHEAD-CLEAN-FRESHWATER-135-LBS-COMPRESSION-/350907095335?pt=Boat_Parts_Accessories_Gear&hash=item51b3b15927&vxp=mtr

    That's a GREAT DEAL.
     
  8. HaMm3r

    HaMm3r Well-Known Member

  9. Rookiemistake

    Rookiemistake Well-Known Member

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    Mattyvac is that one on ebay a direct fit?that would be great if all the other parts just mount the same.is this an easy swapout?
     
  10. HaMm3r

    HaMm3r Well-Known Member

    While I can't say for sure if that block would fit or not, I can say with certainty that it is not the same as the one on my 1999 Merc 25.

    The guy gives the model and sn# in his listing, so you could pull up the schematics for both and compare the part #'s.
     
  11. Dillusion

    Dillusion devilray snob

    Your 99 is different than a 01-05 motor.

    PCI is a great company and the owner is a great guy. I would recommend them but you need to tear down the block yourself anyway.

    The one in the link 'should' fit. It looks exactly like the one I took off my 04 25 when I had it.

    [​IMG]
     
  12. Rookiemistake

    Rookiemistake Well-Known Member

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    Hey matty the guy replied and said he doesnt think it will fit.is there a certain range of years that are compatabale?
     
  13. Dillusion

    Dillusion devilray snob

    Any 2000-2004 power head. I paid 500 for mine a few months ago.
     
  14. Creek Runner

    Creek Runner Well-Known Member

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    You can bore those now, I have a couple machine shops doing them now.

    That's not a brand new power head that is a used power head.

    There are more than 2000-2004 years that are compatible.
     
  15. Rookiemistake

    Rookiemistake Well-Known Member

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    The guy said that head was from an 85 mariner.not sure if it falls in the range
     
  16. Creek Runner

    Creek Runner Well-Known Member

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    No a 1985 will not work.
     
  17. HaMm3r

    HaMm3r Well-Known Member

    No, it's not. Same block. Check the parts diagrams.
     
  18. Dillusion

    Dillusion devilray snob

    I was thinking of the slightly modified block of the model before yours.
     
  19. Creek Runner

    Creek Runner Well-Known Member

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    Correct the 99-present 25 EL' motors are all the same.