Replacement of these parts is vital at regular intervals, and the XU10J4RS engine is somewhat prone to cambelt failure
Peugeot main-dealers don't know there arse from there elbow; dont rely on them for advice
I will try and clear up some of the confusion.
Phase ½ cars are fitted with tensioner part no. 0829 35 (upto build code 08546). With this tensioner, a 136 tooth cambelt must be used.
This tensioner was prone to bearing failure resulting in extensive damage. Peugeot changed the design somewhere around the phase 2/3 crossover (from build code 08547).
The new revised tensioner has part number 0829 84, and must me used with the 137 tooth cambelt (due to the tensioner having a larger radius).
My advice is, regardless of your cars age/phase/build code, order the newer updated tensioner and 137 tooth belt.
This is harder than may first appear. Communicating with a Peugeot parts monkey is like trying to get blood out of a stone.
Good luck peeps