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Mercruiser 140, Hot Battery when trying to start

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  • Mercruiser 140, Hot Battery when trying to start

    I have a Mercruiser 140 attached to a 1987 Doral TRX.
    replaced the alternator belt last night and hooked up the muffs to try and start it. Tried to start the boat and after 4 or 5 tries the battery died. came close to starting before battery died.
    So I got another battery and the motor actually turned over a couple times but wouldn't stay started. Heard some clicking as well.
    Second battery also died and the battery terminal was very hot.

    Going to try it again later tonight with a recharged battery, but any suggestions on what might be wrong??

    I'm hoping it will just start, but not sure.


  • #2
    Re: Mercruiser 140, Hot Battery when trying to start

    is it the cables that are hot or the battery itself?
    here are a couple of posibilities: Check your current drop across the starter when starting, a worn starter can cause a high current draw and heat up the cables. also make sure your cables are tightened properly. and make sure you havn't over-tightened the belt, over-tightening a belt can do wierd stuff also.
    lastly, check for siezed pullies on the drive system,
    Why did you change the belt in the first place?
    How does it crank/run with the belt off?


    • #3
      Re: Mercruiser 140, Hot Battery when trying to start

      I only noticed the nut being hot when i was trying to undo them.
      I changed the belt because it snapped last fall.
      Was out one weekend and boat was running fine on a Saturday. Went to start it Sunday and the boat was dead.
      Noticed the snapped belt when i was putting it away for the winter.
      I never drove the boat after it wouldn't start.
      Is it safe to run the boat without the belt on it?


      • #4
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        Re: Mercruiser 140, Hot Battery when trying to start

        1st This post should be in the Mercruiser forum, not an outboard forum.

        2nd Was this motor Winterized or freeze protected, or are you in a warm enough climate that isn't a problem?

        3d As the previous poster stated, check the voltage drop at the starter while cranking to be sure of good cables and connections.

        If this is a single belt motor, the alternator belt also turns the water pump on the motor,, no alternator, and you may have overheated the motor last time out.

        Remove the spark plugs and turn the motor over, does it crank much faster now? If not then you may have a dragging starter.

        Temporarily loosen the belt and turn the alt by hand to make sure that it is not dragging and causing more work for the starter. If fine then readjust belt.

        Maybe you should test your temp sensor and alarm to be sure that it is working.