Engine noise-knocking? on my 86 mondial cab | FerrariChat
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Engine noise-knocking? on my 86 mondial cab

Discussion in 'Mondial' started by steviep6, May 19, 2010.

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  1. steviep6

    steviep6 Rookie

    Mar 7, 2006
    7
    new york
    Full Name:
    steve psaila
    #1 steviep6, May 19, 2010
    Guys-
    I need some help...started the car up last weekend and heard a knocking sound from the engine. Does not happen all the time, does not increase in speed as the rpms go up, does not seem to be down on power. It seems to happen at idle and maybe seems like when some accessory is kicked on. It will idle and then all of a sudden kick in and then stop after a minute or so. My shop is having a tough time finding the source of the problem. They talked about valves? If it was valve related, wouldnt the noise be constant? Ive had the car for 14 years and if the local race shop cant fix, I guess I'll have to have the car trucked down to Ferrari of Long Island. I'm in Rochester, NY-anybody have a good local shop in Upstate NY? Thanks for your help.
     
  2. mike996

    mike996 F1 Veteran

    Jun 14, 2008
    6,875
    Full Name:
    Mike 996
    #2 mike996, May 19, 2010
    If it REALLY doesn't increase in speed when the engine increases speed, I don't see how it can be engine related. Frankly, it sounds like the ac compressor is kicking on/off but that would be terribly obvious and the knocking speed would change with RPM. The only things I can think of that run and are not tied to eng rpm are windshield wipers, the cooling fans (but they spin awfully fast for a warped/bent blade to knock if it was hitting something), and, of course, the fuel pump.

    Have you listened carefully with a stethascope or rubber hose to try to determine exactly where the noise comes from.

    Re valves - the sound would change speed with eng RPM.

    It is difficult to diagnose via long distance - can you feel this knocking at all? Is it more a knock or more a tap?
     

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