355 Belt sound higher rpms

When is your engine out service?

 

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.

 

Depends on what belt... You cannot ignore anything bad with the timing belts. The result of a timing belt failure is an engine replacement.

 

Check the other three belts first ...
Then decide.
Nobody ever said owning a F355 was going to be easy, or low cost. Fun, yes.

 

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.

 

No access

 

Are you sure it is the belts ? Hard to make that noise out .. I guess as mentioned above check tension of the accessory belts

 

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

 

If the material gets sucked into valves ..not good

 

Sulfur usually comes from a failing cat ..yes
Check it soon

 

I recommend picking one of these up anyways. It is extremely handy to pinpoint a sound and it's only $25 bucks.

https://www.amazon.com/Lisle-52750-Stethoscope-Kit/dp/B0015DLMOO

 

The accessory belts will usually squeal if not tight enough, not produce a "shuffling noise". Difficult to hear in your sound file; is the noise you are trying to describe more like "humming"?

If it is humming, it is more likely to come from a bearing. I would first check the alternator belt tensioner bearing, then the alternator bearing(s) and the AC compressor pully bearing (did you check whether you still have the noise when the AC compressor is "on"?).

 

Sounds like it could be a timing belt or accessory belt issue, maybe a tensioner or pulley starting to wear. At higher RPMs the load on belts increases, which could explain why it only happens above 3–4k. Definitely get it checked sooner rather than later, as belt issues on an F355 can be costly if they fail. Also check for any loose pulleys or misaligned belts, as they can cause similar “shuffling” noises.