[PLuKE]

I am need of some advice on an issue that’s arisen.

My 2013 BMW 330d has started to make a very faint whine noise, related with engine speed and temperature. The car has 127k on the clock.

So on a cold to luke warm engine temperature I can hear a faint whine, mainly on de-acceleration around 1000-1300rpm but also on a light throttle, say in a car park. It makes no difference on the load, A/C, heater etc. Once the engine is getting to full temperature the noise is no more.

Could this be an alternator?

[cross90]

I've been experiencing the same thing recently for the last few 1000 miles, I had it into the stealers for a service and asked them to check it over but said they couldnt find anything wrong and didn't know if they could hear the noise I was referring to when taking it out for a drive.

I drive a 2014 F31 330d S-Drive Auto, sitting at about 82k on the clock now.

As you've mentioned most notable under de-acceleration, can't determine where its coming from myself, it is very faint and not happening all the time.

At times I'm convinced its the transmission with the noise seeming to be very central in the car, but the others it sounds as though its more engine related.....

Seems impossible to replicate aswell to see if others can hear it, its just happens randomly.

From looking around regarding similar sounding issues, I've read it could be the quite possibly be the alternator, but also people reporting the issue disappearing after a transmission service and oil change.

[PLuKE]

Hi,

I also have noticed for many months, in cooler/cold morning that on starting the car the whine noise is there for 2-3 seconds then goes, which makes me think alternator, as it’s just had a big draw cranking the engine? Again it’s not every time, and once the engine is warm/full operating temperature it’s fully gone. The noise comes on light throttle/light de-acceleration.

I shall do some research and keep you informed!

Thanks

[gds54]

Same with my 330d. Done it since I bought it with 73k miles. Not transmission related for me I don't think, does it in N or P.

[PLuKE]

I can’t hear it with no load on the engine. But mines not transmission 100%.

Again it’s faint, with the radio on your wouldn’t hear it, but I listen out for it now, with no radio on.

Luke

[xpro]

Previous 535d did it from new and now my 335d whines at cold start too. 30K miles.

I suspect its the high pressure pump that does it..

[Hypermile]

Originally Posted by PLuKE

Hi,

I also have noticed for many months, in cooler/cold morning that on starting the car the whine noise is there for 2-3 seconds then goes, which makes me think alternator, as it’s just had a big draw cranking the engine? Again it’s not every time, and once the engine is warm/full operating temperature it’s fully gone. The noise comes on light throttle/light de-acceleration.

I shall do some research and keep you informed!

Thanks

The "alternator" NEVER sends power to anything directly except for the battery. When "cranking" the motor, the power is solely drawn from the battery. I sometimes hear the wine in low speeds if my HVAC is on and the car is requesting low A/C compression. It gets loader with higher RPM.