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Results 1 to 11 of 11
  1. #1
    Join Date
    Apr 2016
    Location
    Moncks Corner, sc
    Posts
    16

    Default What block is me Mercury 25 Hp?

    Is my 25 Hp Mercury block the Mercosil block? I'm wanting to rebuild it but not sure what block I have. My serial # is 0D293494 If it helps.

  2. #2
    Join Date
    May 2007
    Location
    Inverary, Ontario, Canada - The Great White North Eh!
    Posts
    9,114

    Default Re: What block is me Mercury 25 Hp?

    Serials 0G202750 and "below" (which is yours) are chrome and can NOT be rebored or honed. 0G202750 and "above" are the Mercosil bores that can be rebored to a max of 30 thou over.
    Graham

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

  3. #3
    Join Date
    Apr 2016
    Location
    Moncks Corner, sc
    Posts
    16

    Default Re: What block is me Mercury 25 Hp?

    Quote Originally Posted by galamb View Post
    Serials 0G202750 and "below" (which is yours) are chrome and can NOT be rebored or honed. 0G202750 and "above" are the Mercosil bores that can be rebored to a max of 30 thou over.
    So im screwed if my cylinder is scratched?

  4. #4
    Join Date
    May 2007
    Location
    Inverary, Ontario, Canada - The Great White North Eh!
    Posts
    9,114

    Default Re: What block is me Mercury 25 Hp?

    Pretty much. Even the Mercosil blocks are a pain to do and not many shops will touch them.

    And even if you could bore it/hone it, by the time you replace the pistons, rings and whatever else you could probably find another powerhead cheaper.

    Just a set of rings will set you back almost 200 bucks (per piston).
    Graham

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

  5. #5
    Join Date
    Nov 2011
    Location
    tennessee
    Posts
    2,616

    Default Re: What block is me Mercury 25 Hp?

    Mercosil blocks have "Mercosil" cast on top of block and there are some earlier models/serials with Mercosil block(1994-04)The earlier models are serial# 0D278000 and up. Rings are $45 a set too...
    Pappys Sales and Service
    Owner and Factory Certified Technician
    Former racer KDBA (Kentucky Drag Boat Association)

  6. #6

    Default Re: What block is me Mercury 25 Hp?

    You are better off with the block you have the chrome is pretty tough. Pull the pistons and see what you have a lot of times they are OK with a little cleaning.

  7. #7
    Join Date
    Apr 2016
    Location
    Moncks Corner, sc
    Posts
    16

    Default Re: What block is me Mercury 25 Hp?

    Quote Originally Posted by flyingscott View Post
    You are better off with the block you have the chrome is pretty tough. Pull the pistons and see what you have a lot of times they are OK with a little cleaning.
    Im going to post pics in a few min

  8. #8
    Join Date
    Apr 2016
    Location
    Moncks Corner, sc
    Posts
    16

    Default Re: What block is me Mercury 25 Hp?

    Click image for larger version. 

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ID:	16210

    What does the big M stand for?

  9. #9

    Default Re: What block is me Mercury 25 Hp?

    M=Mercury. On the #1 cylinder, that is the top one, over on the throttle assembly side it will say either Mercosil or nothing. It is physically cast into the block if it is there.

  10. #10
    Join Date
    Apr 2016
    Location
    Moncks Corner, sc
    Posts
    16

    Default Re: What block is me Mercury 25 Hp?

    Quote Originally Posted by flyingscott View Post
    M=Mercury. On the #1 cylinder, that is the top one, over on the throttle assembly side it will say either Mercosil or nothing. It is physically cast into the block if it is there.
    Click image for larger version. 

Name:	IMG_20170810_181115.jpg 
Views:	13 
Size:	47.9 KB 
ID:	16216

  11. #11
    Join Date
    Apr 2016
    Location
    Moncks Corner, sc
    Posts
    16

    Default Re: What block is me Mercury 25 Hp?

    Quote Originally Posted by flyingscott View Post
    M=Mercury. On the #1 cylinder, that is the top one, over on the throttle assembly side it will say either Mercosil or nothing. It is physically cast into the block if it is there.
    Click image for larger version. 

Name:	IMG_20170810_181115.jpg 
Views:	13 
Size:	47.9 KB 
ID:	16216

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