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Rumble / Low Growl at low RPM

Discussion in 'Carver Yacht' started by snelltyke11, Mar 10, 2013.

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  1. snelltyke11, Mar 10, 2013
    #1
    snelltyke11

    snelltyke11 New Member

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    330 Mariner 1993 makes a low growl, rumble or grinding at low RPM. At 1300 or above goes away. No vibration just a low noise from under boat. Any Ideas.

    Thank you!
  2. SeaEric, Mar 10, 2013
    #2
    SeaEric

    SeaEric YF Historian

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    It may be a noise from one of the transmissions. This was explained to me in the context of a Carver 406 MY a few years ago. The story was that engines now days all turn in the same direction, unlike the "old" days when there were left and right turning engines. So the direction change is now accomplished in the transmission. The one that's running backwards normally makes that noise at low RPM's. As soon as you speed up, it goes away. Again - this was a story about a particular boat told to me by someone unrelated to the deal who claimed to know. YMMV.
  3. Capt Ralph, Mar 10, 2013
    #3
    Capt Ralph

    Capt Ralph Senior Member

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    Rubber cushioned adapter plates between the flywheel and input shaft will rattle when the bushing are worn. Usually goes away in gear.
    Have a real qualified gear man look it over.
  4. RB480, Mar 10, 2013
    #4
    RB480

    RB480 Senior Member

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    It is probably related to the V-drives.
  5. Capt Ralph, Mar 10, 2013
    #5
    Capt Ralph

    Capt Ralph Senior Member

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    Can use more input

    Did somebody mention V drives? I request the OP state what equipment he has; Engine, gear? OP did not spec if in gear but referenced a taller rpm, I assumed clutch not engaged.
    I made a quick reply earlier but if we could get some more data, we may be of more help.
  6. RB480, Mar 11, 2013
    #6
    RB480

    RB480 Senior Member

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    All 1993 Carver 330 Mariners have V-drives
  7. Capt Ralph, Mar 11, 2013
    #7
    Capt Ralph

    Capt Ralph Senior Member

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    O K, what make & Model?
  8. NYCAP123, Mar 11, 2013
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    NYCAP123

    NYCAP123 Senior Member

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    If the noise is from under the boat I'd suspect a worn cutless bearing or lack of lube in the shaft log. I doubt the noise actually goes away, but instead gets masked by the speed of the turning shaft. Sort of like when your car needs an allignment. There'll be a spot where you feel the shake in your wheel, but it seems to disapear when you go faster. If you have a drip shaft log check that you're getting sufficient drip, not too little and not too much. If dripless you may need to have it serviced. Next time you haul check the cutless bearing in your strut.
  9. snelltyke11, Mar 11, 2013
    #9
    snelltyke11

    snelltyke11 New Member

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    Twin 350 Crusader XL, BW Velvet Drive. Complete major tune up week ago including rebuild of carbs. 339 hours both systems. Some sugessted idle is too low and is causing chatter in the gear box due to low pressure at 400 RPM while in gear.
  10. snelltyke11, Mar 11, 2013
    #10
    snelltyke11

    snelltyke11 New Member

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    If I bump it up to 800RPM while in gear the noise goes away. With new carbs and tune up machanic has them crackling like an old muscle car and idle at about 400RPM. This seems too low and it seems that I have lost some control at such a slow speed. Should it not be at about 650RPM at lowest gear speed?
    Thanks.
  11. NYCAP123, Mar 11, 2013
    #11
    NYCAP123

    NYCAP123 Senior Member

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  12. snelltyke11, Mar 11, 2013
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    snelltyke11

    snelltyke11 New Member

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    Thank you, will try this week.
  13. Capt Ralph, Mar 11, 2013
    #13
    Capt Ralph

    Capt Ralph Senior Member

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    O K, now were starting something. Is that the later 500/5000 Borg gear, or the older 72 and Borg V?
    And yes, the idle is to low. Go for 500 in gear, 600 - 650 neutral.
  14. Capt Ralph, Mar 16, 2013
    #14
    Capt Ralph

    Capt Ralph Senior Member

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    Any news?
  15. snelltyke11, Mar 17, 2013
    #15
    snelltyke11

    snelltyke11 New Member

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    Sound Adverted With Some Adjustment...

    Increased RPM to Crusader specs (650 to 700 ingear) also reset trim tabs to "all up position while docking and low speeds" Now its quiet...

    Book says always reset trim tabs to up position after running and use as needed...

    Thanks, I'll keep you updated...
  16. Capt Ralph, Mar 17, 2013
    #16
    Capt Ralph

    Capt Ralph Senior Member

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    650 to 700 IN gear? what rpm you see out of gear?
    Curious,
    rc
  17. snelltyke11, Mar 17, 2013
    #17
    snelltyke11

    snelltyke11 New Member

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    RPM in gear

    I went 600+RPM in gear and only climp to 650 in neutral. The tachs in my carver are not very accurate in that I only have marks every 200RPM So I may borrow a timing light and check it digitally.
    I have very little drag when moving into gear. 33ft and 19" props must not create much drag. I hate these stock tachs...
  18. Capt Ralph, Mar 17, 2013
    #18
    Capt Ralph

    Capt Ralph Senior Member

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    There ya go. rpm sounds near perfect.
    It's been a while since I dealt with timing lights, do they have tachs in them now? I suppose it is easily possible, 4 flashes per revolution (v-8).
    I usually use foil tape and a hand held tach sensor. My father still uses a hand held dial gage with a drag flag, that you hold against the center of the crank pulley. Us old farts don't modernize well.
    Xintex/Aetna makes a wonderful digital tach that will fit into most standard tach dash holes.

    Keep us up on how everything turns out. Safe cruises,
    rc