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  1. #1

    Default 4.3 Mercruiser serious problem - Engines jammed

    Hello FolksJust bought myself a 94 Stingray 18'6" walkthrough. Had it out three times with the wife and kids when starting it to go home the starter motor split (Right down the casting seem). After getting it home and pulling the Starter I thought it would be a good idea to confirm all the teeth on the fly wheel are intact which may have caused this mystery. Got almost all the way round hand cranking and inspecting when it came to an abrupt stop with a CLUNK. Mystery solved!! :o It looks like I'm going to have to tear into this motor and would like to know a few things. Like - are the 4.3 LX Mecruiser motor parts swappable with the GM six cylinder its made from (keeping in mind rotation and what not)-is there a motor rebuild/repair manual out there for this engine-is there a good site for parts (which will actually ship what you order)Any other comments or tips would be greatly appreciatedMy email is andfitz@softhome.netThanksAndrew

  2. #2
    Moderator Bondo's Avatar
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    Default Re: 4.3 Mercruiser serious problem - Engines jammed

    Sorry to here about your Clunk.....Here's some of the answers you seek,Yes, Your motor is the Same basic Motor run in a GM truck,... But You'll need to use Parts from the same Vintage....Rotation IS the Same....I've got a copy of the Mercruiser service manual #18.(GM V-6 262cid (4.3L) Gen.II with balance shaft.... It's a very throrough Manual... If you watch Ebay, You'll see one come up for auction after awhile....I buy 90% of my parts at NAPA, Ask for a copy of the NAPA cat.# MSP-7... It's the newest NAPA marine catalog.....The cover says it's $6.95, But I've Never Paid for one....Have you had any revalations as to What the Clunk Is ?????
    Any Grease is Better,..... Than No Grease at All.......

  3. #3
    Vice Admiral snapperbait's Avatar
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    Default Re: 4.3 Mercruiser serious problem - Engines jammed

    www.ebasicpower.com has always done good by me for any engine parts I've needed...This web page may also be of some help... It has exploded views of some assemblys for your Mercruiser...
    I don't give interviews, and I'm no longer a public figure..

  4. #4

    Default Re: 4.3 Mercruiser serious problem - Engines jammed

    Thanks for the quick and GOOD responseNo to the "clunk" answer, I suspect either a valve dropped or a rod has taken on a direction of its own, but there are no additional "inspection ports" on the side of the crank case or oil pan.The sources you gave me are great.If you have any tips, hints, tricks or tools I should know about that would be great.BTW is there a difference between the starter you buy at NAPA and the one the Mercury site sells?ThanksAndrew

  5. #5
    Vice Admiral snapperbait's Avatar
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    Default Re: 4.3 Mercruiser serious problem - Engines jammed

    As long as the starter is specificaly rated for marine use, there's no difference... Marine starters, alternators, and distrbutors are all either sealed or have spark arrestor screens as not to allow any sparks out which could ignite any flamible vapors that may accumulate in your boats bilge/engine area.. You can also find starters Right Here in the Iboats MegaMall..
    I don't give interviews, and I'm no longer a public figure..

  6. #6
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    Default Re: 4.3 Mercruiser serious problem - Engines jammed

    Sounds like you may be hydraulocking. Remove plugs and try to turn over engine again. Inspect plugs for signs of water. I use this website for reference and buying parts. Great folks... mercruiserparts.comBT

  7. #7

    Default Re: 4.3 Mercruiser serious problem - Engines jammed

    ThanksI will defiantly try the Hydrolock thing before going at the engine. Has anyone used the vented spark plugs?

  8. #8
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    Default Re: 4.3 Mercruiser serious problem - Engines jammed

    I suspect you are right about the Hydro-lock. Motor was running fine and then the starter motor split, yes they will. You lost me with the "vented spark plugs"?? You need to find out why it got water in the cylinders and pay attention as to which ones do and do not have water. I have also had motors which over-rev create valve trouble but it would not have been on start up.

  9. #9
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    Default Re: 4.3 Mercruiser serious problem - Engines jammed

    Andfitz, before you tear into that motor, pull off the stern drive and see if it turns over....you can break either the upper or lower gear set and jam the engine, they are always turning with the engine....

  10. #10

    Default Re: 4.3 Mercruiser serious problem - Engines jammed

    PR/EP (Pressure Relief / Engine Protection) Spark Plugs I understand are specifically designed to protect engines against hydrolock damage. I found it here prep sparkplugs I'll go after hydrolock first and then to the outdriveThanksAndrew

  11. #11
    Lieutenant Commander flashback's Avatar
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    Default Re: 4.3 Mercruiser serious problem - Engines jammed

    Well ya learn something new every day, I've never heard of such plugs, any of you folks ever used them? Andy, be sure to remove the outdrive if removing the plugs doesn,t help,,,,,good luck...
    The Devil to pay, and no pitch hot!

  12. #12
    Moderator Bondo's Avatar
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    Default Re: 4.3 Mercruiser serious problem - Engines jammed

    The Prep-sparkplug is an interesting concept, But, I think I'd rather Tune my engine properly, Rather than Rely on a Blown Sparkplug....Seems that once it Goes-Off, It's Junk,+ Must be replaced....I'll Stick with My ACs....
    Any Grease is Better,..... Than No Grease at All.......

  13. #13

    Default Re: 4.3 Mercruiser serious problem - Engines jammed

    Popped the plugs and cranked it over - sure enough water came out (salt water). Looks like it may have drawn it in through the exhaust. I'll have to look into why that happened. Wonder if dieseling would cause that. Should I shoot a little oil into each cylinder and spin it over with the plugs out to clean it up? (that is after I pick up another starter)Looks like it was defiantly hydrolocked

  14. #14
    Vice Admiral snapperbait's Avatar
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    Default Re: 4.3 Mercruiser serious problem - Engines jammed

    By all means... YES, get some oil in there and turn it....ASAP...
    I don't give interviews, and I'm no longer a public figure..

  15. #15
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    Default Re: 4.3 Mercruiser serious problem - Engines jammed

    Happen to me once, low motor high waves, we changed the oil 3 times that day. Also shoot some starter fluid in the chambers to dry up the water. The first thing to check is the flapper valves, mine were shot, changed em out no problem... so far.Good Luck

  16. #16
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    Default Re: 4.3 Mercruiser serious problem - Engines jammed

    That engine needs to be fired quickly to stop the effects of salt water in the combustion chamber. Next step after that is a leak down test to see if there is a blown head gasket or bent exhaust valve. After that all checks out good, start looking at the exhaust. BT

  17. #17
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    Default Re: 4.3 Mercruiser serious problem - Engines jammed

    This may show nothing but my ignorance as a boater (10 or so years ago), but this exact same thing happend to me once, after turning the motor off while trolling (and kind of letting the boat coast to a stop with the outdrive still engaged) Somehow the engine sucked up a bunch of water through the exhaust, and the engine would not turn over at all.Got it home, drained the water, changed the oil, and it ran perfectly for the remainder of the time I owned the boat

  18. #18
    Moderator Bondo's Avatar
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    Default Re: 4.3 Mercruiser serious problem - Engines jammed

    You Could get as Lucky as Monte, But, If it cranked Hard enough to Split the starter case..??? I'll bet that Something is Bent Somewhere...!!!Either Way, You should get it Started.ASAP..!!!!Starting it will do 2 things.... The Best way to clean an engine, is to Run it... And, Once it starts, You'll Know if it's got to Come Out.....
    Any Grease is Better,..... Than No Grease at All.......

  19. #19
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    Default Re: 4.3 Mercruiser serious problem - Engines jammed

    It has to get started, the sooner the better....like Bondo says, after its running you will know what has to be done....

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