Hum from rear tire area, fuel pump?

[Mikes LS3]

I just developed a slight hum at the left rear tire area. I checked under the hood for an alternator whine/hum, but I only hear it when idling at the left rear tire area. I have an 2008 manual coupe with 32k miles. Anyone else experience this?

[NORTY]

Mike, the way it reads is your car is stationary. Is this correct?

Try filling your fuel tank to the top and listen for it again.

Is the engine idling or does the "hum" pitch change with a slight rev? (say holding 1800rpm?)

Any CEL?

[Mikes LS3]

Originally Posted by NORTY

Mike, the way it reads is your car is stationary. Is this correct?

Try filling your fuel tank to the top and listen for it again.

Is the engine idling or does the "hum" pitch change with a slight rev? (say holding 1800rpm?)

Any CEL?

Yes, the car is stationary and the hum noise was heard after a 2 hour drive. Never heard it before, no CEL and no difference in "hum" pitch was heard as I increased the rpm, mostly due to the exhaust drowning it out. I have the stock NPP exhaust, but even at 1800 rpm with the NPP exhaust valves closed, the hum is so slight it could not be heard.

Today, I started the car up, no hum at idle. I went for a 20 minute drive and still no hum, filled the gas tank up from 1/2 to full, no hum. It's a mystery? I will update with any changes.

Thanks for your response.

[kraz]

hi mike i have the same sound as you left rear tire i have 11,000mi on my 08 z51 m6 i think the sound is from the cooling fans the sound only happins when my car is hot and the cooling fans are on if you fix the problem let me know how to fix mine thanks kraz

[Mikes LS3]

Originally Posted by kraz

hi mike i have the same sound as you left rear tire i have 11,000mi on my 08 z51 m6 i think the sound is from the cooling fans the sound only happins when my car is hot and the cooling fans are on if you fix the problem let me know how to fix mine thanks kraz

Thanks for your response.

I know its is not from the cooling fan. The fan is programmed by the ECM to start at about 220 degrees and increases speed as engine temp rises. I opened my hood to check the fan, alternator etc. and no sounds are coming from there. The sound is definitely coming from the left rear tire area. This weekend I will be going on a lengthly trip and will troubleshoot further. Strangely enough, the hum sound was not present during my last 20 min. ride. I will post an update after the weekend.


Update: The hum is gone! I have driven the car several times and the hum has not returned, crossing my fingers!