There are no visual signs of this failure unless the valve cover to the engine is removed. Upon removal there is a metal fragment that is running loose underneath the valve cover. When this metal piece falls out it can enter the timing chain and cause the engine to seize and the vehicle to have catastrophic engine damage. This part breaks off due to a faulty design of the adjustable timing mechanism (vanos). A redesign of the system or removal and replacement of parts is needed to solve the issue from happening again. As a temporary solution I have replaced the $1000 dollar part which has the possibility of failing again. Please address this issue as it is a widespread issue on the S54 engine on thousands of high end BMW's and leads to a ridiculous fee to fix that can range from $1000-$8000 depending on severity.

- Wayne, NJ, USA

The vanos system in the 2001-2006 BMW M3 is a common part that is prone to failure. The intake and exhaust bolts of the cam gear can sheer off due to improper torquing from the factory and improper hardness of the bolts. The drive shaft of the vanos system is also weak. If the vanos system fails, the cam gear can sheer off, and parts can get into the engine and cause a catastrophic failure. Sometimes, parts can break off into the hood of the car. This system fails without rhyme or reason, seemingly at random. Many owners have had problems with the vanos system. Please observe the following links: www.M3forum.net/M3forum/showthread.php"T=327372 www.M3forum.net/M3forum/showthread.php?T=321494 www.M3forum.net/M3forum/showthread.php"T=212573 a simple google search will yield more results. Sometimes replacing the bolts on the intake and exhaust camshaft with hardened bolts will sometimes fix the issue, but other times, the problem seems random.

- Austin, TX, USA