Renault Megane timing belt - Dieselian
I have recently purchased a 1998 Renault Megane RT1.9 diesel.I bought it with the understanding that a new timing belt needed to be fitted..Every time i fit the new timing belt and turn the engine over the belt slips.Has anyone any ideas.Also does anyone know if a 1999 Clio 1.9 engine will fit into the above Megane.
Renault Megane timing belt - Screwloose

The keyway [such as it is!] shears on the cam pulley. Wise garages send these to the dealers to fit.

When they fail within months, then it's a Renault warranty claim and not £1200 out of their own pockets for doing nothing wrong.