WKMCD

I have a Z51 A6 3LT car. When I start it up and for the next few minutes I get a humming/droning sound. It's almost like diode noise but lower in frequency. It sound like its coming from the right side of the car in front of the passenger seat. I don't know if you can hear it outside the car but you definitely can inside. It seems to go away once the car is warmed up for a couple of minutes.

Anyone else have this?

MikeyTX

The feeding tray for the mice must be empty. The humming/droning sound you hear is the surviving mice praying over their deceased . . . . . .

WKMCD

That was helpful...

Al Engel

Yep - I have same sound - - I believe it is the electric 'air pump' to supply extra air for the cats to heat up quicker. Once the cats have 'lit', the air pump shuts down - no more 'whine', and everybody is 'happy'. This is what I 'believe'... but I'm sure others will have additional wisedom on this subject.

socaljet

I wondered about that and guessed it was coming from a cold torque converter. It seems more pronounced on cooler days to the but only lasts for a quarter mile or so.

WKMCD

That's exactly what I thought it might be. Thanks!

slief

All of the above or is your AC on when you're warming the car up? Could be the compressor you are hearing while the car is at idle.

WKMCD

I turned everything off but the engine and it still made the noise. I think it is the air pump. Just to confirm, does anyone know where the air pump lives in a C7?

Modshack

It is...

KenHorse

I'm curious.. WTF is a "diode noise"?

WKMCD

Ken,

I'm sure you can make me smarter but this is from the C5 service manual.

According to FSM noise problem could be:
1. loose drive pulley
2. loose mounting bolts/screws
3. worn or dirty bearings
4. faulty diode or faulty stator

I had a similar noise in my C5 and it turned out to be a faulty diode in the voltage regulator/alternator. That's why I described the sound as such.

Kevin

KenHorse

Alternator whine, gotcha

MikeyTX

Always glad to lend a helping hand.

BRCC

For what it's worth I have the same car configuration and the same sound. I believe the answers above are correct. Being I had a new engine put in a few weeks back did not recall that sound before and actually recorded it on the iPhone and was going to ask the service manager if he knew what it was. However, now no need being it is common. Thanks forum members.

BRCC

Also saw a Techlink bulletin that in another model (Not Corvette) there was an exact description of the sound that was related to the Brake Booster pump which last around 20 seconds. So it could be a little longer in the Vette.