A common issue on these 2 types of engine the N20/N26 are the timing chain noises such as rattling or rough noise coming from the engine that occurs roughly at the milleage of 100,000+-km. A more severe case of unchanged timing chain is that the chain and components supporting the chain can break away and you are in for a complete engine overhaul making your cost to repair very much higher.
This noise issue indicates that the timing chain sprockets that are already showing early worn signs of the chain, or the related components such as the timing chain guides that are made of plastic are prone to disintegrating over a long period of time since it is inside the engine, it is exposed to chain movements and high heat. Also the timing chain tensioner are prone to wear and tear as well thus not providing enough tension to the chain.
