Power Train Driveline problems of the 2000 Jaguar XJ

Jaguar: Xj8l, 2000: the timing chain guides/tensioners broke causing catastrophic failure to the engine. It could have happened in traffic as it did to a friend with a year older. With such failure the engine stops abruptly, no matter where it is. This risks serious accidents with injury or death on highways. The guides/tensioners fail before 100k miles any time between about 60 and 95k. They are made of plastic. A new kit is available with metal parts but at $1200 cost for the kit and Jaguar does not pay for it, nor the labor to install the new guides, nor the other damage to the engine when the tensioners/guides fail. This situation is a major topic on edmunds, and other sites. This was a major design and manufacturing flaw that has affected this model for years. Why hasn't the NHTSA done something about this major, high risk failure?.