Is there a way of telling if the cam belt has been changed?

Not that i know of best get it done if you don't know get it done £400-500 for a cam belt £2000 for a new engine

If in doubt change it.........

if in doubt remove the right top camcover and check the belt for small cracks or missing teeth. if you can still read the markings on the belt quite clear it's fairly new (in general). best is to manually turn the crank so you can inspect the complete belt.

you can also start the engine, but it will be hard to see any damage as the belt will trun round quite fast.

 

if you can't read any of the markings it's best to replace it.

 

BUT..the tensioner is also VERY important and there's no easy way to check if it has been replaced. if the tensioner fails the belt will slip, no matter how new it is.