Weird Humming Sound on Cold Engine Start

[ussy7861]

I have a weird humming noise on a cold engine over 1000rpm.

I have maintained the revs and the humming is only heard in the cabin and not in the engine bay.

Once the engine is at optimal temperature the sound disappears.

Can someone please advise on where the sound is coming from.

It can be heard more from the glove box area.

[furtula]

Which engine?

Was the AC on? Disable AC, try again.

You said you were holding the rpm's steady, but sounds like the throttle was blipped a few times and sound increased with it.

Was it exceptionally cold that time you started it? 

Cars also don't like cold weather, and cold start can bring a lot of weird noises. If when it heats up the sound is gone, and the car behaves normally, i would not bother too much,that way you will start obsessing with every tiny sound.

[ussy7861]

Hi it's a 1.6vvti 2007

The ac is never on when the car is started.

The sound doesn't appear on first start in the morning only when I have been driving and the engine cools down to cold temperature the sound appears.

[furtula]

By AC i mean heater in general, not just the cooling.

You did not answer regarding the throttle, if you press the pedal a bit, and the rpm's go up, does the sound increase, or stay the same?

 

[ussy7861]

In the video I pressed the pedal down and kept it steady at 1100 rpm so the sound is constant.

The only time the sound appears is when you start the engine an it idles over 1100rpm and then it slowly lowers to 600 rpm.