During a recent repair, my technician said that the timing chain on my 2014 X5 3.0 L diesel SE was "loose," albeit not critically damaged. I have completed 224,000 km, and it has not yet been changed. He now asserts that it is unnecessary to do the task since the N57 engine does not have timing chain issues. I suspect he may be reconsidering his decision due to his undervaluation of the job. Do you have any recommendations?