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Noise while turning crank via pulley nut

Discussion in '365 GT4 2+2/400/412' started by s14kev, Aug 28, 2022.

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  1. s14kev

    s14kev Rookie

    Oct 17, 2020
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    Kevin Au
    #1 s14kev, Aug 28, 2022
    I'm noticing a noise when I turn my engine over in a clockwise direction using a 36mm nut on the crank pulley nut. It's a slight 'brrr' almost like a plastic guide or pawl running over a tooth. I think it's coming from the timing chain tensioner area. Is this normal? Didn't want to continuing turning it over if it wasn't. I imagine the tensioner spring is pushing the tensioner pad against the chain but was unsure if this should be silent.

    I have the distributor caps off and all belts off the engine when turning it over. Also is it supposed to be fairly difficult to turn these over? The spark plugs are in but it requires way more force than any other engine I've worked on. That being said, it's the first V12 I've tried to turn the crank over on so.
     
  2. raemin

    raemin Formula 3

    Jan 16, 2007
    2,277
    Lyon (FR)
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    R. Emin
    #2 raemin, Aug 28, 2022
    What do you mean by clockwise?

    Turning this engine requires to rotate the 4 camshafts, each having double springs on the cams, so you are fighting against 48 springs. Requires a bit of persuasion.
     
  3. s14kev

    s14kev Rookie

    Oct 17, 2020
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    Kevin Au
    #3 s14kev, Aug 28, 2022
    As in I’m turning the crank in a clockwise direction when I’m facing the front of the engine.
     
  4. SouthJersey400i

    SouthJersey400i Formula 3

    Mar 14, 2007
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    Ken Battle
    #4 SouthJersey400i, Aug 29, 2022
    Remove the plugs and see if there is a difference.
     
  5. s14kev

    s14kev Rookie

    Oct 17, 2020
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    Kevin Au
    #5 s14kev, Aug 29, 2022
    I'm more concerned about the slight rattle noise when turning the engine over. I think it is from the tensioner area. Engine ran fine before this restoration. Has anyone else turning the engine over by the crank pulley nut experienced this?
     
  6. Sergio Tavares

    Sergio Tavares Formula 3

    Nov 15, 2018
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    Sergio Tavares
    #6 Sergio Tavares, Sep 22, 2022
    Tensioner pad is worn off, best to inspect this
     
  7. Rifledriver

    Rifledriver Three Time F1 World Champ

    Apr 29, 2004
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    Brian Crall
    #7 Rifledriver, Sep 22, 2022
    Unlike 4's,6's, and V8's a 12 has no time when there is no compression stroke happening. As a resuly they turn quite smoothly with no points at which it is noticeably hard. That may be fooling you. On the other hand if it is easy to turn it does not bode well for condition.

    As for the noise. Isolate it. Stethescopes are cheap. And there are electronic options too.
     
  8. Ak Jim

    Ak Jim F1 Veteran
    Owner Rossa Subscribed

    Dec 23, 2007
    9,399
    North Pole AK
    #8 Ak Jim, Sep 25, 2022
    Have you checked the chain tension?
     

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