- Messages
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- City
- SOUTHWICK
- State
- MA
- Country
- United States
- What I Drive
- 2018 VW Atlas
I'm stumped and would love some help on this one.
My wife's 2018 VW Atlas, 6-cyl, 4-motion, ~78K mi, is making a loud mechanical rattle/knocking/buzzing noise. It is very prominent in the cabin, and sounds/feels like it is coming from center right side, under vehicle. It happens on cold start, sometimes. It happens at idle, sometimes. But, it always occurs under load and, curiously, starts at exactly 2500RPM. From idle to this point, everything is silent -- this is probably the clue that solves the case but, as described below, I can't figure it out. No CEL or unusual codes -- just an unholy noise. Car runs and drives fine, as far as I can tell, even during the racket.
If I drive in manual mode and continue gradually increasing speed, it appears at 2500RPM and basically disappears at 5500RPM. It does it whether in drive or in neutral. It almost always happens in park with an RPM sweep. While I initially thought it was the in-tank fuel pump, I do not hear it when the pump primes when the door is opened before starting ignition. And, using OBDeleven, I used Basic Settings to cycle the fuel pump manually and I could not get it to cause the issue. I removed the two belly pans on the right side and could not find anything obviously wrong (e.g., loose heat shield, fastener, etc.). With someone loading the engine while I am under it, I swear the noise is in the tank -- so, with no other leads, I replaced the in-tank pump today (no fun!). As feared, problem is still present.
For what it is worth, I replaced the high pressure direct injection pump last month (due to fault code and poor engine performance). Car ran horrible with that failed pump... and perfect once replaced. Probably 500 miles since then. Anyway, it would make some sense this new noise seemingly coming from in-tank was somehow related. Grasping at straws, I thought reverberation from a poorly installed high pressure pump was causing the noise back at the tank. That pump does seem to sound louder now than it did after I replaced it. So, I removed it again today, fearing I perhaps damaged the cam and this noise was just traveling through the fuel lines. But, using my iPhone and an inspection mirror, the cam lobe looks just fine, and the cam follower looks normal with very little witness marking. And, everything about the high pressure pump assembly looks fine, as well.
I am not aware of anything else mechanical in the vicinity of the noise (center right, underside) but know how these noises can travel in weird ways through the car.
Desperate for help... much appreciated!
My wife's 2018 VW Atlas, 6-cyl, 4-motion, ~78K mi, is making a loud mechanical rattle/knocking/buzzing noise. It is very prominent in the cabin, and sounds/feels like it is coming from center right side, under vehicle. It happens on cold start, sometimes. It happens at idle, sometimes. But, it always occurs under load and, curiously, starts at exactly 2500RPM. From idle to this point, everything is silent -- this is probably the clue that solves the case but, as described below, I can't figure it out. No CEL or unusual codes -- just an unholy noise. Car runs and drives fine, as far as I can tell, even during the racket.
If I drive in manual mode and continue gradually increasing speed, it appears at 2500RPM and basically disappears at 5500RPM. It does it whether in drive or in neutral. It almost always happens in park with an RPM sweep. While I initially thought it was the in-tank fuel pump, I do not hear it when the pump primes when the door is opened before starting ignition. And, using OBDeleven, I used Basic Settings to cycle the fuel pump manually and I could not get it to cause the issue. I removed the two belly pans on the right side and could not find anything obviously wrong (e.g., loose heat shield, fastener, etc.). With someone loading the engine while I am under it, I swear the noise is in the tank -- so, with no other leads, I replaced the in-tank pump today (no fun!). As feared, problem is still present.
For what it is worth, I replaced the high pressure direct injection pump last month (due to fault code and poor engine performance). Car ran horrible with that failed pump... and perfect once replaced. Probably 500 miles since then. Anyway, it would make some sense this new noise seemingly coming from in-tank was somehow related. Grasping at straws, I thought reverberation from a poorly installed high pressure pump was causing the noise back at the tank. That pump does seem to sound louder now than it did after I replaced it. So, I removed it again today, fearing I perhaps damaged the cam and this noise was just traveling through the fuel lines. But, using my iPhone and an inspection mirror, the cam lobe looks just fine, and the cam follower looks normal with very little witness marking. And, everything about the high pressure pump assembly looks fine, as well.
I am not aware of anything else mechanical in the vicinity of the noise (center right, underside) but know how these noises can travel in weird ways through the car.
Desperate for help... much appreciated!
