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Winterization of a Mercruiser 496 MAG High Output Engine

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  • Winterization of a Mercruiser 496 MAG High Output Engine

    Thanks in advance for helping with this question. We are considering purchasing a larger boat that has a Mercruiser 496 Mag High Output engine. We currently have a deckboat with an Mercury Outboard motor and love the fact we can go out, even during colder months. We live on a large lake hosting large boats and cruisers and feel it would be safer to move into a larger boat. The salesperson for the boat we are considering insists that the Mercruiser 496 Mag High Output engine with the air actuating water release will solve our dilemma about moving from the convenience of an winter boating with an outboard.

    We are a bit apprehensive about this since the Mercury website says the warranty won't cover any cracked engine blocks due to lack of proper winterization.

    Before we make this big jump to a much more expensive boat we want to be sure we can safely use the quick release winterization feature of this engine and go out all year round.

    Can anyone give us their opinion based on experience with this motor??


  • #2
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    Re: Winterization of a Mercruiser 496 MAG High Output Engine

    I wouldn't expect that system to work except during testing. It's scarry.
    If you want to boat all winter, get a FWC system installed and drain the raw water side of the heat exchanger, manifolds/risers, and raw water pump (Bravo drives) and make sure nothing is clogging the drains. That is fairly easy. With a raw water cooled system you also need to drain the block. And that can get real hard to get to on todays engines with MPI.
    Don S.


    Please, no PM's (Private Messages) regarding boat/engine problems.
    That is what the forums are for.
    Only forum/moderator issues will be answered in PM's.