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  1. #1

    Default 1990 Mercruiser 4.3 LX - Starting problems.

    Hi Guys,

    I am new to the forum but have been browsing for quite a while.

    I would like to introduce myself, my name is Damien. I am 25 and a marine engineer based in Wales, UK.

    Last year a customer came to us with his boat. A 1990 Rinker, fitted with a 4.3 LX V6 Mercruiser.

    The customer had just bought the boat (without hearing it running) and when he got it home, he disconnected his trailer without chocking it and the boat roller into farming equipment, writing off the stern drive. I replaced the stern drive and transom shield with brand new units. Upon starting the engine I noticed a horrendous knocking from the bottom end. Instantly I phoned the customer and suggested a strip down/possible rebuild. Being as tight as he is, he decided to take the engine elsewhere to be rebuilt, whilst I agreed to re-install it once it had been done.

    A year later, the engine comes back to us.

    I installed the engine and tried to start it up, only to find out the timing was out and all of the plug leads had been put in the wrong place. I set the base timing, put all of the leads where they should be and still then engine refuses to start/is hard to start.

    Now the engine will start briefly, it will pump out masses of white smoke and eventually stall.

    I have tried everything and am out of ideas. I am hoping you guys can help me out as I may have overlooked something.

    WHAT I HAVE DONE;

    Checked compression on all cylinders, figures returned 150PSI on all.
    Bypassed fuel tank and pre-engine filter by hooking up my own supply.
    Installed brand new spark plugs.
    Set base timing and checked correct firing order.
    Fuel is being sprayed out of carb when throttle is pumped.
    Brand new starter motor.
    Brand new battery.
    New oil filter & engine oil.

    As said, i have tried everything I can think of. Any help would be greatly appreciated.

    And dont be afraid of suggesting even the most basic things, I never get offended

    Thanks.

  2. #2
    Moderator achris's Avatar
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    Default Re: 1990 Mercruiser 4.3 LX - Starting problems.

    Hi Damien and welcome to iBoats...

    Have you checked the valve timing? As the plug wiring was wrong, I would also check that the camshaft is opening the valves in the right sequence. They may have put the wrong cam in... I would also pressure test the cooling system to ensure an incorrect gasket hasn't been put on anywhere in the cooling system. White smoke is usually an indicator of water in the combustion process. If the manifold gasket is the wrong one, there could be a possibility of water ingestion..

    Good luck...

    Chris......

  3. #3
    Lieutenant Junior Grade
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    Default Re: 1990 Mercruiser 4.3 LX - Starting problems.

    What was the problem with the noise in the lower end and what repairs were made ???
    If you can read this thank a teacher.If you can read it in english THANK A VETERAN

  4. #4

    Default Re: 1990 Mercruiser 4.3 LX - Starting problems.

    achris

    Valve timing and sequence is fine, I have checked this.

    Now water in the combustion process, this didn't cross my mind. The chap who rebuilt the engine supplied gaskets etc and it is very possible that he may have fitted the wrong ones.

    Ensign

    I didn't physically see the damaged parts put apparently 1) a core plug had fallen out 2) damaged con rod on #3 and 3) damaged piston on #6

    Its a shame the customer was so tight and decided to get it rebuilt by a friend because as far as I know, I am working with a dog here.

    Thanks for the help so far.

  5. #5
    Moderator achris's Avatar
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    Default Re: 1990 Mercruiser 4.3 LX - Starting problems.

    Quote Originally Posted by verado350 View Post
    ... 1) a core plug had fallen out ....
    oh... 1) worries me... The one thing core plugs don't do is fall out. The usual reason is because water left in the block has frozen and pushed it out... The other thing water freezing in an engine block does....cracks it, and exhaust manifolds. And heads. And the crack may not be big enough to show on a compression test, but get a bit of combustion going and water WILL get into a cylinder. You live in Wales... Plenty of freezing temperatures there! Start looking for hairline cracks... Sorry....

    Chris.........
    The world takes on a whole new perspective when viewed from 100' below...



    1972 Bertram 'Bahia Mar' 20
    2006 Mercruiser 4.3MPI (0W617679) w/Alpha 1 Gen II (0W829301)
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    Please don't send service questions in private messages. That's what the forum is for. Messages of thanks, always accepted.
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  6. #6

    Default Re: 1990 Mercruiser 4.3 LX - Starting problems.

    Achris.

    This worried me too.

    Initially I thought, well if the chap who is rebuilding the engine knows what he is on about, he should spot things like this. That said, all of the little mistakes he has made, has damaged this confidence I once had.

  7. #7
    Moderator achris's Avatar
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    Default Re: 1990 Mercruiser 4.3 LX - Starting problems.

    Quote Originally Posted by verado350 View Post
    Achris.

    This worried me too.

    Initially I thought, well if the chap who is rebuilding the engine knows what he is on about, he should spot things like this. That said, all of the little mistakes he has made, has damaged this confidence I once had.
    And the prize goes to the man who knows what he's on about, who set up the spark leads on the wrong plugs!!!
    I would take EVERYTHING he says or does, not with a grain of salt, but a whole truck load of the stuff!!!!
    First thing I would do.... clamp off the exit water hoses and pressure up the block, heads ect.... Take it to 20 psi and leave it there for about 3 hours... If it passes that test, move on... I'd bet it fails...

  8. #8
    Honorary Moderator Emeritus Don S's Avatar
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    Default Re: 1990 Mercruiser 4.3 LX - Starting problems.

    Or the risers or manifolds are shot. If the gasket surfaces are shot, there will be water in cylinders.
    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.

  9. #9
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    Default Re: 1990 Mercruiser 4.3 LX - Starting problems.

    I agree,I think you're going to find that you've been wasting your time on a cracked block !!! Don't jump into the fire
    If you can read this thank a teacher.If you can read it in english THANK A VETERAN

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