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Repowering 454 Merccruser on port engine of 1986 Carver

Discussion in 'Carver Yacht' started by Coach John, Jul 31, 2022.

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  1. Coach John, Jul 31, 2022
    #1
    Coach John

    Coach John New Member

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    I recently purchased a 1986 Carver 4207 and the port engine has low compression (35psi) in one gf the cylinders. The other cylinders are 120 psi. The mechanic recommended replacing the engine. he said that he can get a plug and play engine for 6 k, and it would be another 2k to install it. In order to lift the engine out of the vessel, and replace it with a new one, he said that it would require cutting into the floor. It's about 3/8" flooring. The engine room is normally accessed under the stairs, but getting a hoist in there is impossible. The starboard engine has been running fine. We mainly use it as a floating condo for our family this season, and are considering replacing the engine next year. The engines ran well during a 100 mile trip last year before this happened.

    Does anyone have any experience replacing an engine on a 4207?
    Any thoughts, or recommendations?

    Attached Files:

  2. MBevins, Jul 31, 2022
    #2
    MBevins

    MBevins Senior Member

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    My initial reaction is that seems rich. You'll know better when the rest chime in.
  3. Coach John, Jul 31, 2022
    #3
    Coach John

    Coach John New Member

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    Thanks for the feedback. The engines are original with 2500 hours on them, and I'm not sure how long the starboard engine will last, before it needs to be replaced.
  4. MBevins, Jul 31, 2022
    #4
    MBevins

    MBevins Senior Member

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    Not sure why you wouldn't rebuild or buy reman long blocks.
  5. Capt J, Jul 31, 2022
    #5
    Capt J

    Capt J Senior Member

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    It's not worth the trouble these days. Hard to find good rebuilders, takes more time, the price difference isn't that big of a difference. It's better to get a new long block with warranty and put it in.......

    OP, if you're going to go through all of that trouble, REPLACE both engines at the same time. 2500 hours is A LOT on gas inboards and you'll save labor and headaches. Change exhaust manifolds and risers also when you do it.
  6. BigChief, Jul 31, 2022
    #6
    BigChief

    BigChief Member

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    Boroscope that cylinder or Pull the intake and head on that side and check the valves, the block and crank on the 454 is solid.
  7. Coach John, Jul 31, 2022
    #7
    Coach John

    Coach John New Member

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    That makes sense to me. Do you think the cost would be about 15k to replace both engines at the same time?
  8. Capt J, Jul 31, 2022
    #8
    Capt J

    Capt J Senior Member

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    Ask your mechanic
  9. MBevins, Jul 31, 2022
    #9
    MBevins

    MBevins Senior Member

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    The other question is how well do you trust your mechanic?
    Unless you have a history with him, you should be looking for a second opinion.
  10. Coach John, Jul 31, 2022
    #10
    Coach John

    Coach John New Member

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    I agree with you. Will do.
  11. boatpoor, Jul 31, 2022
    #11
    boatpoor

    boatpoor Active Member

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    Did your mechanic put oil in the weak cylinder and check the compression again to try to determine if it was a head or the rings?
  12. Capt Ralph, Jul 31, 2022
    #12
    Capt Ralph

    Capt Ralph Senior Member

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    What is "before this happened"??
    Suddenly started running poor?
    Or discovered and you did not know you had a problem?

    Low lung compression can come from bad rings, yes but crank case pressure can help reinforce that theory.
    A bad valve can do the same.
    Leaking head gasket can do a low compression real also.
    Bad cam lobe also.
    Poor moon phase.
    Poor install of the compression gauge.
    Lots to check before condemning an engine.

    I'd get another tech in there and shop for more quotes.

    LBCs at 2500 hours are near but not at end of life (IMO). Lots here depend on previous operation and services.
    If the boat is a keeper (for at least a long while), really need replacement, then replace them both with new engines and cruise with confidence.
    Now, if the boat is really a keeper, You thought about repowering with a pair of Cummins diesels?
  13. Coach John, Aug 1, 2022
    #13
    Coach John

    Coach John New Member

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    Thanks for the feedback. Lots to consider. I like the thought of repowering with Cummins diesels! Is it difficult to make the conversion? What’s the prince difference?
  14. Pascal, Aug 1, 2022
    #14
    Pascal

    Pascal Senior Member

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    It’s a big price difference. You can get factory reman cummins with factory warranty and pretty much all new parts except for the block. I went this route 4 years ago to replace the Detroit Diesels with 6CTAs in my 53. On a 40 footer the 6BTAs would probably be enough but you re still looking at about $30k per engine and gear. Add new shafts, props, engine beds and probably new struts and shaft seals… it’s a $100k option. Not worth it if you use it as a condo.

    I agree with the others, if you like the boat, patch it up or put in a long block. Before deciding though I d make sure the issue isn’t just a valve or head gasket in which case replacing or repairing the head maybe enough.
  15. Coach John, Aug 2, 2022
    #15
    Coach John

    Coach John New Member

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    Thanks for the feedback.
  16. Coach John, Aug 2, 2022
    #16
    Coach John

    Coach John New Member

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    Thank you for the feedback. It makes sense. The biggest challenge is engine access. It will require cutting into the floor, taking the windows out and bringing the engine through the side.
  17. MBevins, Aug 2, 2022
    #17
    MBevins

    MBevins Senior Member

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    Actually you may find this hard to accept, but reality is, everything you describe is pretty well standard operating procedure. Done all the time, no big deal.
    Speaking from first hand experience.
  18. Pascal, Aug 2, 2022
    #18
    Pascal

    Pascal Senior Member

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    I don’t get it. Engines are under the salon floors, right? Carver didn’t build hatches in the floor to get the engines out?? That’s ridiculous. You should be able to get them out after removing the manifolds.
  19. Capt Ralph, Aug 2, 2022
    #19
    Capt Ralph

    Capt Ralph Senior Member

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    Get it diagnosed well before you start loosing sleep.
    Heck, A short block may just go up the companionway...
  20. MBevins, Aug 2, 2022
    #20
    MBevins

    MBevins Senior Member

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    Coach John... listen to what we're telling you, There are decades of experience on this forum.
    To start with, none of us are convinced your engine is even dead, You need to confirm this doing what we suggested and not necessarily with your current mechanic. Once this is done then you know what your really dealing with.
    The idea that you need to start cutting up your boat to remove a little gas engine is , frankly, hard to believe. The sole should lift up .
    Removing the saloon window to insert a lifting device is pretty normal. Strip it down to the block and out it goes.

    Diesels may sound nice but probably isn't financially feasible.
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