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Scary Noise!

Discussion in '308/328' started by PreppyRockrChick, Sep 14, 2019.

  1. PreppyRockrChick

    Jan 22, 2018
    17
    WNY
    Full Name:
    Jules
    I have a 1978 carbed 308 GTS. It has been running great! No problems starting, it has plenty of oil. When I drive it, a mystery noise has started when I hit around 3500 RPM. I'm doubting it's a rod as I have checked out some youtube videos and the sound is different. It's almost like MAYBE a fan could be hitting something when the revs get that high? I'm afraid to go faster to see if it goes away or gets worse. And if the revs go higher, the pitch of the vibration goes higher as well. Anyone ever have this one?
     
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  3. Brian Harper

    Brian Harper F1 Rookie
    Owner

    Feb 17, 2006
    3,824
    San Jose area
    Full Name:
    Brian Harper
    Consistent or more inconsistent/random in nature?

    I had a light knocking noise that was sort of random that turned out to be a ruined lower cam drive bearing. Didn't sound like a fan blade though.
     
  4. BigTex

    BigTex Seven Time F1 World Champ
    Rossa Subscribed Owner

    Dec 6, 2002
    74,113
    Houston, Texas
    Full Name:
    Bubba
    Check the A/C compressor lines.....they can get against the body, and transmit engine vibrations that would be speed sensitive, like that.

    Otherwise I would suggest a stethoscope and start looking at engine bearings, as posted above mine.
    Hope it's the A/c lines, put some foam blocks in there will fix that!
     
  5. ClydeM

    ClydeM F1 Veteran
    Rossa Subscribed Owner

    Nov 4, 2003
    8,829
    Wayne, NJ
    Full Name:
    Clyde E. McMurdy
    Perhaps the A/C belt? That will generate a tapping. A plug extender shorting would tap as well. I'd expect you to hear it at idle, but probably not under load.
     
  6. yelcab

    yelcab F1 World Champ
    Consultant

    Nov 29, 2001
    10,521
    San Carlos, CA
    Full Name:
    Mitchell Le
    Ms. Julie, where is your location? Perhaps you can take it to a local Ferrari mechanic, or a Ferrari DIYer can offer their opinion upon listening to the noise. Location is important in the level of Ferrari support you can find.
     
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  8. Lawrence Coppari

    Lawrence Coppari Formula 3

    Apr 29, 2002
    1,951
    Kingsport, TN
    Full Name:
    Lawrence A. Coppari
    Check to see of the ram air inlet is vibrating, evidently getting excited by engine vibration. My 328 did that. It occurred at a little over 3K rpms. Above and below that engine speed, the resonance went away.
     
  9. PreppyRockrChick

    Jan 22, 2018
    17
    WNY
    Full Name:
    Jules
    So, upon further investigation......It is a vibration that happens at around 3500RPM, then goes away. Def something rubbing on something. I'm going to check the A/C stuff as we were charging it before the noise started. Thanks all! Now, I get to change out the oil pressure sender again. Always an adventure
     
  10. Martin308GTB

    Martin308GTB F1 Rookie

    Jan 22, 2003
    4,125
    Black Forest Germany
    Full Name:
    Martin N.
    If it's a A/C hose you will hear the noise from coming the right rear. Been there. It took almost 5 years till I found the issue and it almost drove me nuts. The cause was a hack job A/C recharge, where they retightened the fittings on the compressor and altered the angle of the fittings.

    Best from Germany
    Martin
     
    JuLiTrO likes this.
  11. Skippr1999

    Skippr1999 F1 Rookie
    Silver Subscribed

    Dec 22, 2009
    3,018
    I’m dealing with this now for the second time due to A/C updates. Both times it was the air box hitting either the compressor or the frame. When upgrading the A/C, there is very little clearance in that area. Both times has meant modifying the air box fit.
    Have a friend ride with you and have them hang out the passenger window and place their hand into the air intake to feel for vibrations. This should narrow things down quickly.

    Mine is a 328 though.
     
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  13. Dane

    Dane Formula 3
    Rossa Subscribed Owner

    Apr 25, 2002
    1,325
    Manhattan, MT
    Full Name:
    Dane
    Side note. This is why this forum rocks. Person has an issue, and so many people are willing to help. Hoping the best for you and your 308, Julie.
     
    19633500GT and Skippr1999 like this.
  14. Saabguy

    Saabguy Formula 3
    Silver Subscribed

    Mar 28, 2012
    1,574
    Shreveport, LA
    ... and no one even mentioned belt change intervals. Great forum! ;-)

    Lester


     

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