[Legge]

Has anybody elso noticed a faint twittering noise at low speeds once the engine has warmed up properly? Never heard it while driving at higher speeds, but it's possible that the road noises are covering it. Sometimes I can hear it even when stationary and the engine has been switched off, so it's not coming from the engine itself or the aircon. I was wondering if it has something to do with the new thermal management system introduced in the new M270 engine?

 

[Greguk]

Hi legge, I do notice a slight rattle at low speeds in low gears, which sometimes drives me mad !!

As for a twittering noise, not sure what you mean, the one I notice is quite cranky but not that loud but noticeable. Is this what u mean?

 

[Legge]

Don't think it's a rattle. More like a faint chirping noise that comes and goes. Do you have a diesel or a petrol?

Edited by: Legge

 

[The Swedish Guy]

Isn´t it simply the wastegate ( "dump-valve") on the turbocharger you hear??

 

[Legge]

Then it's a weird sounding waste gate. The chirping usually comes in 2-5 second series. I think it happens when coasting or driving with a very light foot. Just came to work I could hear the noise very faintly for a moment after I had switched off the car. You really cant't hear it over the radio.

 

[Greguk]

Hi leggy' I have diesel an yes can hear mine when coasting at low gears. You gonna get MB to look at it?

 

[Legge]

Probably at the first service. The noise has been there since my car was brand new. I noticed it only when driving without the radio. Somehow, I have a hunch that it's deemed a feature

 

[Legge]

Did some testing on the weekend. The noise is coming from the A/C. Should have guessed as it sounds a bit like the noise that some fridges make. It's probably the coolant circulating in the pipes. BTW, I have Thermatic if that makes any difference.

 

[Legge]

So no one else noticed this? Now that the weather is getting warmer, it's pretty clear that the source is aircon. Easily heard when cruising in town.

 

[TerryA213]

I've noticed a bit of something like this - I would say it sounds a bit like a rattle snake ???

No warning lights up though and it seems to be behaving normally so not tooo bothered at present

 

[Legge]

Yeah...or maybe like a cricket

The sound occurs when the aircon compressor adjusts pressures between the low and hight pressure sides. I can't hear it at all when it's really hot and the compressor is running non stop. MB took a look at it and made sure that the system isn't low on refridgerant. They thought, it's normal as long as the system is producing cool air.Edited by: Legge

 

[TerryA213]

think you are right - turned the air con off and the noise stops - turn it back on and the twittering re-appears - bit annoying but not a problem