Yamaha 15 2 stroke

Discussion in 'Outboard Maintenance' started by DblHaul, Mar 14, 2013.

  1. DblHaul

    DblHaul SW Florida

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    I thought I'd post these pictures of the thermostat from my 15. I've flushed it well after saltwater use but I bought it used, so I didn't know if the previous owner did.
    The bottom cylinder is getting much hotter than the top one so I suspect the gunk has blocked a coolant passage. I'm going  to take the head off to look further. I'm going to try salt-away but I've read a few posts that it really doesn't help.[​IMG]
    [​IMG]
     
  2. used to have that same motor and it is one of the best motors ever had mine new put over 3000 hours on it beat it to hell with hittin ground and whatnot still ran perfect the day I sold it and its still running.
     

  3. DblHaul

    DblHaul SW Florida

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    Shadowcast777 - I think they're good motors too. I got this one to replace one that I bought new in 2000 but was stolen. I'm hoping I can get this one fixed up.
     
  4. CurtisWright

    CurtisWright Light, Strong, Cheap. Pick Two.

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    Be very very careful breaking the head bolts loose. They can easily break off in the case. If they are stiff, work them in and out until they come out easily. Dont try to muscle them out.

    I broke on off in my 25 Yami
     
  5. Creek Runner

    Creek Runner Well-Known Member

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    ^ Nothing a little Blue Wrench can't handle!
     
  6. Frank_Sebastian

    Frank_Sebastian Well-Known Member

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    Hi Creek Runner,

    I live in Sebastian and my family and I keep our boats on lifts, so we seldom flush them. I want to know where to get "Blue Wrench" and is it a tool or penetrating oil.

    Thanks and best regards,
    Frank_S

    PS I am used to working with a torch in one hand and a wrench in the other, but don't enjoy it.
    Frank
     
  7. Brett

    Brett > PRO STAFF <

    I grew up with 2 "blue wrenches", often used consecutively ;)

    [​IMG]

    and the other

    [​IMG]
     
  8. Creek Runner

    Creek Runner Well-Known Member

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    The latter is the one! Sorry frank wasn't referring to a product, talking about a torch.
     
  9. DuckNut

    DuckNut Brandon, FL

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    Frank- and everyone else
    A mixture of 50% ATF (auto trans fluid) and 50% acetone is the best penetrating lube you can get.

    Look around on machinist forums and you will find the same.
     
  10. cutrunner

    cutrunner Cert. Yamaha technician

    Brett thats a plasma torch lol.
     
  11. Brett

    Brett > PRO STAFF <

    [​IMG]

    Not quite CR, look closely.
    It's just an oxy-acetylene cutting torch.
    Plasma torch has a high voltage power cable
    and a different head

    [​IMG]

    I can afford oxy-acetylene, but not a plasma setup.  ;)
     
  12. DblHaul

    DblHaul SW Florida

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    I finally had time to remove the head. The head bolts came off easily (might be a first!) It was not pretty.
    [​IMG]

    The passage circled in yellow was completely blocked by white corrosion. In this picture I had already scraped some of it off.

    [​IMG]

    Heat damage on head:
    [​IMG]

    Blocked passage on the head as well:
    [​IMG]

    I've got a new head and gasket on order - not even going to try and clean this up. This motor runs well except for a rough idle...
     
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