Grinding noise

Discussion in 'General Maintenance/Repair Questions' started by JPGator, Aug 9, 2019.

  1. JPGator

    JPGator Active Member

    215
    Apr 25, 2019
    2007 Sundancer 340
    Mercruiser 8.1S
    ’07 340 with 8.1’s

    What kind of noise does an impeller make when it goes bad?

    Departing the anchorage both engine started and stabilized. Then I noticed the port engine RPM’s act sporadic, paused the radio and listened to a clunking/grinding sound. Quickly placed the engine into neutral-no change. Tried reserve perhaps to free debris but nothing and then the engine quit. Limped home on one engine. Belts are fine, oil levels good. No over temps.

    Thoughts or suggestions?
     
  2. Golfman25

    Golfman25 Well-Known Member

    720
    Sep 12, 2009
    IL
    281
    V8
    Since the impeller is rubber, I doubt you'll hear any noise. Yours sounds like something internal. Good luck.
     
  3. JPGator

    JPGator Active Member

    215
    Apr 25, 2019
    2007 Sundancer 340
    Mercruiser 8.1S
    Thanks. Guess I’m gonna need it.
     
  4. KevinC

    KevinC Well-Known Member

    Feb 25, 2011
    Long Island, NY
    2004 340 Sundancer
    Twin 8.1 V-drives
    Did the sounds seem to be coming from the engine interior or more outside? When it quit did it seem more like a lockup or turning off?

    What was your alternator putting out and what is the status of your batteries? Perhaps the alternator let loose and stopped putting out voltage, when battery voltage drops the ECM will go offline and everything will shutdown.

    Take if one step at a time unless you feel it's locked and an engine internal issue.

    -Kevin
     
  5. JPGator

    JPGator Active Member

    215
    Apr 25, 2019
    2007 Sundancer 340
    Mercruiser 8.1S
    The engine RPM’s typically stabilize at 600. The engine started and automatically dropped to 300-400 with erratic changes. The grinding/clunking noise was hard to discern exactly where it was coming from but I’m thinking inside the engine bay. Engaging the engine into gear did nothing to change the rpms or stop the noise until she simply quit. There was no shaking so it didn’t fee like we ran over any debris.
     
  6. KevinC

    KevinC Well-Known Member

    Feb 25, 2011
    Long Island, NY
    2004 340 Sundancer
    Twin 8.1 V-drives
    There are a number of external components like the alternator that could fail. You said temps were good so we can probably skip the raw water pump for now. Since the engine shut down I start with examining the alternator and its output. If you did not charge the batteries overnight you could start there but if they were on the ac convertor then they'll probably show good even if the alternator was not charging.

    -Kevin
     
  7. JPGator

    JPGator Active Member

    215
    Apr 25, 2019
    2007 Sundancer 340
    Mercruiser 8.1S
    Boats connected at the dock so that probably won’t work. I’m heading out to the boat shortly to take a look at things in the day light. If you think of anything else shoot me a text.
     
  8. JPGator

    JPGator Active Member

    215
    Apr 25, 2019
    2007 Sundancer 340
    Mercruiser 8.1S
    I have no earthly idea!

    The boat started up just fine. Took videos of the belts and alternator and everything looks normal. Put the engine in gear, out of gear, reverse. Everything worked normal.

    Next step is to take her out this afternoon.
     
    Last edited: Aug 10, 2019
  9. cfd95

    cfd95 Member

    327
    Nov 5, 2013
    Northport Long Island
    2002 310 Sundancer
    350 Horizons
    V Drives
    If your boat has V-drives the clunking was probably the transmission damper plate because the RPM were low due to a cylinder misfire or low rpm from a bad IAC valve.
     
  10. JPGator

    JPGator Active Member

    215
    Apr 25, 2019
    2007 Sundancer 340
    Mercruiser 8.1S
    Is this a one time thing or something that needs to be fixed immediately.
     
  11. cfd95

    cfd95 Member

    327
    Nov 5, 2013
    Northport Long Island
    2002 310 Sundancer
    350 Horizons
    V Drives
    The IAC valve regulates the idle.
    They are known to go bad and are a common problem on these motors.
     
  12. JPGator

    JPGator Active Member

    215
    Apr 25, 2019
    2007 Sundancer 340
    Mercruiser 8.1S
    How can I test it?

    Internet says the idle should be higher if it failed. Mine seem to be what same when I started the boat this afternoon.
     
  13. scoflaw

    scoflaw Well-Known Member

    Aug 10, 2011
    cape cod mass, cape coral fl
    1999 Powerquest legend 260 sx
    502 mpi Bravo 1
    Not so. I'd replace it, common problem, sometimes it throws a code sometimes not. Good place to start.
     
    JPGator likes this.
  14. JPGator

    JPGator Active Member

    215
    Apr 25, 2019
    2007 Sundancer 340
    Mercruiser 8.1S
    Yesterday I went for a swim in our nasty marina to get a first hand look at the prop and shaft. Nothing was stuck or wedged around the shaft/prop and the prop itself had no damage. As for me time will determine whether that disgusting water kills me.
    I started the engine again and it ran fine. No issues with the RPMs, temps or anything really and obviously the banging plate noise was not there. Took the boat out for a quick cruise in the no wake zone putting the engine in forward/reverse/neutral etc. Lots of turns, spins and not a hiccup.

    This morning I spoke with my mechanic and he seems to think it was most likely something getting trapped in the prop which later freed itself on the way home. Had I done any significant damage the boat would run differently, which it doesn’t, and since all the engine parameters are normal there really isn’t anything much to do.

    Anyhow, thoughts and opinions are always welcome.
     
  15. Mr Mac

    Mr Mac Member

    43
    Feb 27, 2019
    Apollo Beach, FL
    1997 330 Sundancer
    Name Slàinte Mhath!
    Twin 454 Mercruiser with V-drive
    Sounds like you may have dodged a bullet here. I would repeat the scenario of heading out to the open water and listed closely to everything. Get her out in the open and slowly increase RPMs and see what happens.
     
    JPGator likes this.

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