As you're talking about a cam belt I am presuming it's got the 1.2 four cylinder engine? If so then here's the "official" recommendation:
http://fiat.mopar.eu/contents/brand...elt_replacement/timing-belt-leaflets-fiat.pdf So 5 years OR 72,000 miles, whichever comes first, for our wee FIRE Engines. As you can see it's a mileage and/or time dependent task. It's very tempting to think that because the mileage is well below the recommended change interval that you can extend the time before renewing it. This is not valid thinking as a belt that does a lot of low speed running with short journeys and lots of stopping and starting is actually being subjected to much greater stresses than one which covers a much higher annual mileage cruising the motorway or open road. Hi
As to the need for a water pump? Well, the timing belt is driven by the crankshaft. It runs from the crank sprocket, at the bottom of the front of the engine, up around the tensioning bearing, around the camshaft sprocket and down around the water pump back to the crankshaft sprocket. It's vanishingly seldom that problems come about with the cam or crank sprocket - although newer engines like your's have a hydraulically actuated VVT pulley which might develop an oil leak if you're very unlucky - However the tensioning bearing and water pump both have "sealed for life" bearings which can, and do, occasionally fail. The water pump is by far the most common, often due to the seal failing and then allowing coolant to wash the lubricant out followed shortly by the bearing failing. My advice would be to always do a water pump when renewing the timing belt (Many of the manufacturers now produce all in one kits which include the water pump and they wouldn't do that unless there was a big demand). The 1.2 from around 2011 onwards was an "interference" engine, (basically, if you've got a VVT cam sprocket then the engine is interference) so if the belt breaks or comes off the sprockets the valves and pistons will get catastrophically familiar with each other and you're looking at a substantial bill to sort it all out. By the way, unless the auxiliary (fan in old language) belt has been recently changed, get them to put a new one on when they are reassembling - the old one has got to be removed for access anyway so they should only charge you the price of the belt itself.
We have this FIRE based engine in both my Panda and our older boy's Punto. Our Panda only does a few thousand miles a year now we're retired and is non interference anyway being pre 2011. Our boy does more miles in his Punto, which does have the VVT pulley, around 8,000 yearly. So neither vehicle is doing high mileage. I keep a watch on them and once the vehicle in question has passed the 4 year mark since last renewal I mark it up for doing at some convenient time, and when weather permits, during the next year. Typically then I'm doing a belt change around every 4.5 to 5 years on either vehicle. Here's a good guide as to what the procedure entails
https://pmmonline.co.uk/technical/belt-replacement-guide-fiat-500/ As cam belts go it's actually one of the simpler ones to do and most competent garages should find no problem doing it.
Just in case it's of interest. Not only Fiat incorporate the water pump into the cam belt drive train and I've done many of this type in my life. It's really very unusual to find a cam belt directly, and of itself, failing (unless it's been grossly wrongly tensioned when it was fitted) It's not at all unusual to find a bearing, either tensioner or water pump, considerably "under the weather" and, of the two, the water pump is much the more likely suspect.
