I own a 2006 E90 M47 that produces a ticking noise when the vehicle reaches optimal temperatures.
A few months ago, I operated my vehicle with low oil pressure, and a friend suggested that I might have caused low-end knock. However, after changing the oil and filter, we did not observe any metallic particles in the filter. Additionally, we placed four strong magnets beneath the oil during drainage and found no metal shavings. The ticking noise did not entirely dissipate with the revs, leading us to conclude that it was due to chain slap. The vehicle just had maintenance, including the replacement of the timing chain, tensioner, water pump, steering pump, auxiliary belt, and all gaskets, about two weeks ago at a mileage of 165,000.
However, the noise persists. We have also eliminated lifter tick, as it is audible only from the bottom of the engine, predominantly on the driver's side, but not detectable with the hood open. I have included a link to my YouTube video at the end of this post. Thank you for your assistance; I recently invested $2,000 to eliminate this sound and was informed by the garage that it was chain slap, which is quite frustrating. To be fair, the car drives well and accelerates smoothly; I simply detest this noise.
The most accurate description of the ticking sound is that, when idling, it produces a characteristic diesel tractor "duhduhduh" noise, with the ticking occurring in various rhythms such as tick.......tick tick......tick tick tick tick.............tick. However, upon revving the engine, the ticking will synchronise with the vehicle's operation.