I've recently bought a second-hand XE 20d (180 PS), and I can say I really enjoy this car. However, I've noticed a strange knocking noise from the engine, which gradually disappears over the first 5-7km after cold or not-so-warm start. From inside the car, it sounds like someone would hit the engine block with a wrench lightly. The knocking changes with the engine speed.
I've attached a short audio sample, where the engine goes from 1400 rpm to 2000 rpm, then shifts up and again begins from 1500 rpm. The sample is heavily amplified and eq'd, so the actual sound is slightly different and not as loud. For example you wouldn't notice the noise when music is playing.
The noise appears under the following conditions:
- engine isn't fully warmed up
- throttle is applied (immediately disappears otherwise)
- car is accelerating in low gears (e.g. when driving in a city)
I really would like to know if others experience the same with this engine, and how this compares to the sewing machine rattle issue. The car is definitely beyond its run-in phase.