I dunno... but the OP said he was told that belts don't last that long on Fiat and Alfa engines and THAT was the reason to change the belt on his 500.
I'm just saying change the belt if it needs changing, not just because a completely un-related engine made 10 years ago once had a dicky tensioner..
Visually inspect the belt. I'm sure that with just 35k on it, your belt will look shiny, supple and have no visible wear on the teeth (they have tiny pimples moulded on them). :thumbs:
If it's matt, dry-looking and the teeth are "rounded" and the rubber surface is smooth.. or the belt has cracks in it, then it is worn out and so do change it..
The only other areas that can fail is the tensioner and the water pump. I'm guessing (hoping) your pump is so new that "it can't posssssibly go wrong" yet..
but the tensioner.. have a look.
If it's clean and dry and has no corrosion on it, and it's correctly tensioned, then it's in as good shape as you can visually deduce. When they go, it's the bearings that collapse or the sprung tension falls off (loose tensioner... it's all factory torqued, isn't it?
).
If your tension is good, then it's unlikely to come loose now, after all this time. If the tensioner is quiet when it runs, then the bearings are pretty happy.
I ran a tensioner for 120,000 miles once by mistake .. It was absoluetely knackered... but that's way different to throwing a good one away at just a quarter of that mileage..
Ralf S.