Technical Cambelt noise

[Steviejam]

Hi, I posted here last year when I had my cambelt, tensioner and waterpump done. The car is making a whirring noise from the cambelt most noticeable at around 1700 rpm.
I've had it checked by 2 different mechanics who both said the tension was set right but one of them swapped the tensioner anyway and the car is still making an identical noise.
Both mechanics say it doesn't sound like a bearing noise and say it must just be the belt resonating!
I've driven around 8000 miles since the belt change and it hasn't got any better (or worse!)
What I'd like to know is, is there anything else in circuit that could cause this, other than waterpump or tensioner? Was wondering about harmonic balancer?
Also on looking on Internet I noticed on a Honda forum about a balancer shaft pulley being loose. Is there a balancer shaft on the bravo?!
Another bit of info I saw suggested the screw mounting the tensioner was bent. Would this have been changed with a tensioner change or do you use the old screw?
Any help or info on the whole bravo cambelt set up would be very useful as I'm seriously scratching my head here!

 

[lyubohar]

Had exactly the same case last month...In fact - I still have it. Two different teams disassembled everything and could not find the source of the whirring. They both swore tensioners and belt are fine, so it's either a "noisy" water pump or the alternator itself.

Mind you I have replaced water pump, belts and tensioners 5 months ago with aftermarket ones (not OEM).

Here's my original thread, hope it helps:
https://www.fiatforum.com/bravo/344937-whining-sound-anyone-can-recognize.html

I am driving the car normally, the sound is still there, but does not get worse and since there's nothing else I can do, I just don't care now

 

[get]

Do you hear that sound while driving, or when the car is in the neutral?

 

[Steviejam]

Both. It seems to go away at higher revs unless its just that the frequency gets higher and gets drowned out by the engine! If you rev the engine and let it settle back to idling, it's definitely loudest at around 1700 rpm. It's not a screech or grinding noise. More of a slight whine.

 

[850kd]

Similar symptoms to mine . See Lyubohar's thread link above.

 

[Steviejam]

Took the top cambelt cover off today. No visible wear on the belt however I did notice that there is a very slight gap on the back edge of each belt tooth and the teeth on the cam. The front edge is flush against the cam tooth. I'm no expert but shouldn't the belt teeth fit snugly between the cam teeth on both sides? I'm wondering whether this slight difference in profile is causing the whirring noise?

 

[brandonbillingham]

Had a similar problem with a Peugeot I had before my fiat. Turned out to be the water pump.