Teflonso
Active Member
I wasn't sure whether to post this in the engine or some other forum, so Mods, please move it if you see fit. Anyway............. someone please tell me what this strange noise is.
My E350 Estate is a mere 1700 miles old and in normal running is as quiet as a church mouse. But in slow traffic, there is a periodic noise (sounds to be from the rear but my ears aren't as good as they used to be), almost like a pump running and it is very noticable. I haven't timed it, to check if there is any regularity, but at a guess I'd say it runs for 4-6 seconds about every half minute to a minute.
The only thing I can imagine is that it is either fuel pump or the Urea pump for the exhaust dosing system. But if one of those it is way, way too loud and the urea is going to be empty long before first service. It definately isn't aircon or heating related, because it still happens when climate is turned off. It happens whether the car is stationary or moving. I never notice it when at continuous speed above maybe 5-10mph. Still happens if the Econ mode (auto start/stop) is turned off. I don't have any fancy extra air suspension, only what came as standard.
It spoils a terrific car and I'm sure it shouldn't be there, but I've had enough experience of taking a car under warranty to a dealer to sort out "that noise" and I'd like a few bullets in mind before I wander over.
Please, someone give me a clue!
.
My E350 Estate is a mere 1700 miles old and in normal running is as quiet as a church mouse. But in slow traffic, there is a periodic noise (sounds to be from the rear but my ears aren't as good as they used to be), almost like a pump running and it is very noticable. I haven't timed it, to check if there is any regularity, but at a guess I'd say it runs for 4-6 seconds about every half minute to a minute.
The only thing I can imagine is that it is either fuel pump or the Urea pump for the exhaust dosing system. But if one of those it is way, way too loud and the urea is going to be empty long before first service. It definately isn't aircon or heating related, because it still happens when climate is turned off. It happens whether the car is stationary or moving. I never notice it when at continuous speed above maybe 5-10mph. Still happens if the Econ mode (auto start/stop) is turned off. I don't have any fancy extra air suspension, only what came as standard.
It spoils a terrific car and I'm sure it shouldn't be there, but I've had enough experience of taking a car under warranty to a dealer to sort out "that noise" and I'd like a few bullets in mind before I wander over.
Please, someone give me a clue!
.
