Whining sound? - The Unofficial BMW M5 Messageboard (m5board.com)

vics · 12th October 2004, 23:57

Gang; when car's cold, a whining sound ocurrs for approx 45 seconds & goes away. Tell me this is normal....

DZeckhausen · 13th October 2004, 00:13

Quote:

Originally Posted by vics

Gang; when car's cold, a whining sound ocurrs for approx 45 seconds & goes away. Tell me this is normal....

Hey! I've got that same whining sound. It goes like this: "Honey, these leather seats are so darned cold!" Then after about 45 seconds, the seat heaters kick in and the whining stops.

DrewKeen · 13th October 2004, 00:15

hah, I don't have the same problem you do Dave, luckily.

Does it only whine when the engine is cold or does it do it all the time?

EdP · 13th October 2004, 00:35

I get a slight chirp on start-up, which I assume is the belt, but no whining as a cold-start symptom. I do hear a feint whining sound that definitely is steering related. I hear it during slow manuevers (parking, pulling into the garage, etc.), especially when in sport mode. I'm assuming this is normal too (?) Doesn't sound like what you're describing, as it's not temp related.

tetherM5 · 13th October 2004, 01:15

It is normal, that is your smog pump operating. I would compare it to the sound a handheld black and decker running. Sort of a whinning, whirring type sound.

vics · 13th October 2004, 03:19

Quote:

Originally Posted by tetherM5

It is normal, that is your smog pump operating. I would compare it to the sound a handheld black and decker running. Sort of a whinning, whirring type sound.

Sounds like it my friend - why only when cold & for short duration?
Not a power steering sound; more like a turbo whine for 45 seconds - that's what I tell my neighbors anyways ....

tetherM5 · 13th October 2004, 03:57

The smog pump is designed to introduce compressed air into the exhaust headers to provide additional oxygen for the combustion of CO and HC's during the initial "super" cold environment directly after a cold start (a real cold start when the car has been sitting for 6+ hours.) This is the time when the mixture is significantly rich and the low temperature of the combustion chamber results in a very raw exhaust release. After the 30 seconds or so, the cylinders are able to provide effective and complete burning of the mixture.ffice

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XrayMD · 13th October 2004, 04:10

Correct info on the pump. Also, of interest is that BMW says that this is "normal". WHat I would like to know is if it is normal, how come it didnt start making that noise for me until very recently. I've had the car for 2 years now and it never made the whine on cold start in winter.

BMW says the same thing about the whining noise from some of the power steering units which is load in "sport" mode and mostly heard when slow turning (like into a driveway). If it's normal, why do some cars NOT make that noise?

gsfent · 14th October 2004, 02:13

Quote:

Originally Posted by vics

Gang; when car's cold, a whining sound ocurrs for approx 45 seconds & goes away. Tell me this is normal....

I believe BMW calls it the auxiliary air pump. It is for smog as others have said. I had one replaced under warranty. The new one is barely audible, although it can be heard. Seems a volume adjustment on the radio should solve the problem!!

Regards,
Jerry

SouthshoreM6 · 14th October 2004, 16:17

Quote:

Originally Posted by gsfent

I believe BMW calls it the auxiliary air pump. It is for smog as others have said. I had one replaced under warranty. The new one is barely audible, although it can be heard. Seems a volume adjustment on the radio should solve the problem!!

Regards,
Jerry

I had mine replaced at 42K miles under warranty - it was called the secondary air pump by my dealer, preheats the cats? I can just hear the new one, the old one sounded like a jet engine at start up!