355 - Belt sound higher rpms | FerrariChat

355 Belt sound higher rpms

Discussion in '348/355' started by amazingtrails, Oct 10, 2025 at 12:01 PM.

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  1. amazingtrails

    amazingtrails Karting

    Jan 4, 2025
    144
    Hello, I own a 1997 f355 spider (gated manual). 36k miles. Car runs great. However lately i've noticed a belt type "shuffling" noise at higher RPMs. I don't hear it idling. It is fairly loud in higher gears and above 3-4k rpms. The exhaust often drowns out the sound especially when my windows and top are down. Thoughts?
     
  2. yelcab

    yelcab F1 World Champ
    Consultant

    Nov 29, 2001
    13,689
    San Carlos, CA
    Full Name:
    Mitchell Le
    When is your engine out service?
     
  3. amazingtrails

    amazingtrails Karting

    Jan 4, 2025
    144
    it’s been 3 years according to the previous owner. I was hoping to wait another 2 years.
     
  4. yelcab

    yelcab F1 World Champ
    Consultant

    Nov 29, 2001
    13,689
    San Carlos, CA
    Full Name:
    Mitchell Le
    You have to figure out which belt is doing the shuffling noise. There are 5 belts. Two timing belts, one AC belt, one Alt / water pump belt, and one PS belt. They all have tensioners that may be too loose. From the bottom of the car, you can feel for tension on two belts, from the top you can access one belt, and there is no way to check tension on the timing belts unless you ... remove the engine. And by then, you might as well change them and the tensioners.
     
  5. amazingtrails

    amazingtrails Karting

    Jan 4, 2025
    144
    Other than the annoying noise is it a problem if I just do nothing and wait for the next engine out service in 2 years?
     
  6. yelcab

    yelcab F1 World Champ
    Consultant

    Nov 29, 2001
    13,689
    San Carlos, CA
    Full Name:
    Mitchell Le
    Depends on what belt... You cannot ignore anything bad with the timing belts. The result of a timing belt failure is an engine replacement.
     
  7. amazingtrails

    amazingtrails Karting

    Jan 4, 2025
    144
    Right but in order to even check the timing belt tension I would need an engine out so that's a bit of a dilemma.
     
  8. yelcab

    yelcab F1 World Champ
    Consultant

    Nov 29, 2001
    13,689
    San Carlos, CA
    Full Name:
    Mitchell Le
    Check the other three belts first ...
    Then decide.
    Nobody ever said owning a F355 was going to be easy, or low cost. Fun, yes.
     
    amazingtrails likes this.
  9. amazingtrails

    amazingtrails Karting

    Jan 4, 2025
    144
    Thanks for your help. By checking them do you mean just pulling on them to make sure they are tight ?
     
  10. yelcab

    yelcab F1 World Champ
    Consultant

    Nov 29, 2001
    13,689
    San Carlos, CA
    Full Name:
    Mitchell Le
    Technically, there is a frequency spec for each belt. However, that is pretty hard to do with engine in the car. So, do it the old fashion way.

    1. The PS belt is small, and must be really tight. Push on it, it should not give any deflection at all.
    2. The AC belt is second smallest and should give 1/4 inch deflection.
    3. The Alt-waterpump belt is big, and long. That should give you 1/2 inch deflection at the long side.

    This is just ball park, unscientific, take-it-with-a-grain-of-salt advise.

    While you are under there, check to make sure all nuts bolts fasteners tensioners are nice and tight.
     
    amazingtrails likes this.
  11. amazingtrails

    amazingtrails Karting

    Jan 4, 2025
    144
    thanks for the info. I have attached a sound file in case you can diagnose from the sound.

    https://drive.google.com/file/d/1mwBx34rUrta13ZFajRGgKaxLClgIgMmu/view?usp=drive_link
     
  12. flash32

    flash32 F1 Veteran

    Aug 22, 2008
    7,157
    Central NJ
    Full Name:
    Dominick
  13. amazingtrails

    amazingtrails Karting

    Jan 4, 2025
    144
    Try again.
     
  14. flash32

    flash32 F1 Veteran

    Aug 22, 2008
    7,157
    Central NJ
    Full Name:
    Dominick
    Are you sure it is the belts ? Hard to make that noise out .. I guess as mentioned above check tension of the accessory belts
     
  15. amazingtrails

    amazingtrails Karting

    Jan 4, 2025
    144
    No I'm not sure it's the belts. I have no idea but it has been getting progressively louder and it's louder at higher rpms. The shuffling sound is clearer if you play it from your phone. It's like background noise to the exhaust.
     
  16. flash32

    flash32 F1 Veteran

    Aug 22, 2008
    7,157
    Central NJ
    Full Name:
    Dominick
    It sounds more like intake or exhaust air issue ..like the flaps in intake or the cats failing (movement of the cells inside)

    I think a mechanic stethoscope and someone that pressing the gas and releasing it and you should narrow it down some business
     
  17. amazingtrails

    amazingtrails Karting

    Jan 4, 2025
    144
    Thanks. I hope it’s the cats. Much easier and cheaper fix than engine out belts. What happens if the cats fail completely?
     
  18. flash32

    flash32 F1 Veteran

    Aug 22, 2008
    7,157
    Central NJ
    Full Name:
    Dominick
    If the material gets sucked into valves ..not good
     
  19. amazingtrails

    amazingtrails Karting

    Jan 4, 2025
    144
    Oh also I often smell a sulfur type smell, could this be a sign as well?
     
  20. flash32

    flash32 F1 Veteran

    Aug 22, 2008
    7,157
    Central NJ
    Full Name:
    Dominick
    Sulfur usually comes from a failing cat ..yes
    Check it soon
     
  21. amazingtrails

    amazingtrails Karting

    Jan 4, 2025
    144
    I’ll take it to the shop tomorrow. Thanks!
     

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