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Exhaust Manifolds & Risers

Discussion in 'Technical Discussion' started by 1000 islands, Nov 28, 2015.

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  1. 1000 islands, Nov 28, 2015
    #1
    1000 islands

    1000 islands Member

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    Apr 20, 2013
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    Ivy Lea
    I need to change the exhaust manifolds on my 7.4L Mercruiser inboard.

    As I search the net for them I've found quite a few that say they are for my engine, but the prices vary up to $400.00 From ones that say salt water only to ones that are for fresh water only and of course ones that are good for both.

    I want to change them over the winter so the boat will be ready early in the spring.

    Can I use any manifold as long as it is for a 7.4L Mercruiser ?

    Did I mention that I'm not that skilled as a mechanic ?
  2. Capt J, Nov 28, 2015
    #2
    Capt J

    Capt J Senior Member

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    Some are better than others. Get studs and put them in the 2 outside bolt holes, it makes hanging the new manifold MUCH easier. I'd stick with either Mercruiser or Barr's.
  3. Capt Ralph, Nov 28, 2015
    #3
    Capt Ralph

    Capt Ralph Senior Member

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    Satsuma, FL
    Are your manifolds fresh water cooled and the risers are raw water?
    Have we been over this before on/or another post?
  4. 1000 islands, Nov 28, 2015
    #4
    1000 islands

    1000 islands Member

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    Not exactly, I think. I'm now looking to buy and all the choices are confusing.

    Yes it is all fresh, raw water cooled.
  5. Capt Ralph, Nov 28, 2015
    #5
    Capt Ralph

    Capt Ralph Senior Member

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    When in doubt, stay factory.

    Is there a problem with the fresh water manifolds?

    Risers are usually sacrificial.
  6. 1000 islands, Dec 3, 2015
    #6
    1000 islands

    1000 islands Member

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    The boat was in salt water with a previous owner, but how long ago or for how long I don't know.

    It was sold to me as a fresh water boat and the surveyor obviously didn't catch that it wasn't.