2012 C250CDI Odd Noise When parked.

[Colin_b]

If I park my 2012 C250CDI, assuming the engine is warm, an odd noise starts after an hour and keeps occurring for at least 4 hours.

The car is running perfectly otherwise, using no oil or coolant, just this odd noise, which is loud enough to draw attention to the car.

Anyone any idea what it might be? I assume it is related to the engine cooling, and appears to be coming from around the ABs unit.

The noise can be heard in the youtube link below....

https://www.youtube.com/watch?v=hBXRet0mwFE&feature=youtu.be

 

[Colin_b]

I took the car to the dealer today. Initially met with some scepticism, but the car co-operated and nade the noise!

It appears to be the fuel pump randomly turning on, and the noise is the pressure relief valve.

They tested the pump, and it is fine. However there was a software update which they have applied, and that appears to have stopped the noise.

If it reappears, then a new pump.