A common characteristic of Direct Injection engines is a clacking/ticking when the injectors fire. It does sound a bit like playing cards stuck between bicycle spokes. Perfectly normal sound -- no cause for concern.
@Jwork980 Now I know why your engine sounds louder than mine--I accelerate quite a bit more economical.
I tried to make a video to highlight the interior sound of my cabin when accelerating at nearly the same speed. It was hard to do with my son in the backseat. Again, definitely no metallic-y sound that I hear. This is not at all a scientific comparison, but it should give you an idea of the characteristic sound the engine makes when accelerating under 2,500 RPM.
Thanks guys! I am heading to the dealer to pick up plates this week, I?m going to ask to drive another one and if that does not sound the same, I?ll have them look at mine. *side note: that?s a notoriously short on ramp to a highway, hence the quick acceleration. I just figured that would be the best way to get the sound on film - that being said, I hear it when accelerating at a ?normal? rate, too. @Zee - the metal-to-metal rubbing is the exact sound I?m concerned about. Yours definitely sounds different. I?ll check back in after I talk to the dealer.
So I drove another new QX30 at the dealer yesterday - it was way quieter. Took the salesman for a ride in mine and he definitely noticed the difference. We did notice that my hood was a little loose, so they adjusted that and it?s a bit better, but I have a service appointment for Thursday. We will see if they notice anything. Thanks everyone for the advice - I will post back if I hear anything out of the ordinary.
@Jwork980: Great follow up! I'm glad you were able to confirm a definite sound difference between your QX30 and another one. A loose hood seems odd, but then again, another member posted about a loose connection to the gear selector that caused all sorts of electrical problems.
I mentioned this in another thread, but I feel like the engine is a little too quiet on the inside (not a bad problem to have when you want a relaxing drive). I hope they're able to resolve the noise situation with your car. Keep us posted!
Ok. After taking the car in twice, the technician said the noise is just the dual clutch. He said others have explained it as the sound of knives rubbing together - like a tiny chef sharpening his knives in the engine. Silly, but accurate! So, I know the sound is normal but still sounds louder than I would have anticipated from a luxury vehicle. So I think my next tack will be to find out how to dampen the noise.
The DCT sounds like a chef sharpening knives? Based on my 10K miles of driving, I've never heard anything like that coming from the DCT. Does the noise still occur below 52 MPH? I have read in another Mercedes-Benz forum about a CLA owner (same engine/transmission) that had to take the car into the dealership because the transmission specs were off.
I compared my video with your video again using headphones and I can definitely hear something in your car versus mine. It does sound like a scraping noise, almost as if you had bad/stuck calipers (e.g.,