What Drives the camshaft of a 1.6HDi engine?

A camshaft timing belt.

The manufacturers give a mileage of around 150,000 miles before replacing but i'd recommend replacement at 100,000 miles max and i would also replace the tensioner & guide pulleys. You can buy a kit containing all of these.

Another thing to check/replace is the front pulley as it has an oscillation damper built into it and part of that is a thin steel band that compresses the rubber damper. The band wears through and snaps, it can then come out of the back of the pulley & cut into the lower cam belt cover and the belt with potentially disastrous results..!

If in any doubt, replace it - even though its about £110, it's alot cheaper than a repair bill for the results of a snapped cam belt. My pulley went at around 87,000 miles while driving across France, luckily I heard a noise & stopped the engine before it touched the belt but the lower cover had a neat slot cut into it..!