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Mercruiser 454 blown headgasket or cracked block?

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  • Mercruiser 454 blown headgasket or cracked block?

    I just purchased a 1995 Rinker with a 454 mercruiser. Original owner said engine worked fine but when he went to start it at home after sitting for 3 months it would not work and he noticed water in the oil and assumed it has a cracked block. The thing is the block was just replaced 2 years ago and has less than 20 hours on it. Also he said he has started it several times with no problems since the last time it was in the water. What is the easiest way to check for a cracked block or a blown head gasket?


  • #2
    Re: Mercruiser 454 blown headgasket or cracked block?

    depends on where the crack is or the break in the gaasket. if the plugs are not wet with water it usually will rule out a cyl area. after that its a matter of tear down and inspect. however I would dissconnect the manifolds from the seawater and pressure test the block/heads assy before removing anything. why was the block replaced last time? is this fresh water(closed) cooled or raw water cooled?
    no tech questions by PM, they wont get answered.
    you have to be trusted by the people that you lie to .

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    • #3
      Re: Mercruiser 454 blown headgasket or cracked block?

      As with all marine engines, check the exhaust manifolds first! That way, if that's your problem, you may not have to check for a cracked block or blown head gasket.

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