Timing Drive System
The 2.7-litre diesel engine used in both the X350 and X358 were fitted with a Dayco High Tenacity (HT) or ‘white’ timing belt as their original equipment fitment. The HT belt is unique and patented to Dayco, which is why workshops undertaking a timing belt replacement need to realise that only by fitting a Dayco HT timing belt kit can they be assured of a genuine like-for-like replacement.
Auxiliary Drive System
Despite being subject to inevitable wear and tear during the lifespan of the engine, the front end auxiliary drive (FEAD) system has not traditionally been subject to any particular maintenance or replacement schedule. However, some vehicle manufacturers are now beginning to introduce FEAD system maintenance into their service schedules, which opens the door for the independent sector to apply similar service principles to the auxiliary belt and the associated components, such as tensioners and idlers, that together make up the FEAD system and take advantage of a genuinely new revenue opportunity.
There are a number of very important reasons why technicians should examine the FEAD system. These include the fact that although it is not directly a safety critical component, the auxiliary belt in the X350/358 drives so many vital components – alternator, power steering pump, air conditioning compressor and water pump – that even if its failure does not directly stop the vehicle, it will certainly result in the engine overheating.