r2boxers

I am getting a slight howl in the front of the engine when RPM drops from over 2500 RPM to idle. This is my 2007 Z06. Have disconnected the belt and it still makes the noise. Have ruled out water pump, altenator, power steering. Harmonic balancer is also in good shape. Don't know if anyone else has had this problem. Can not hear when in cabin. Sound is more apparent when the hood is open. There are times that it will not make the howl sound, but more than not. Any ideas are appreciated. Have in shop today to replace radiator and hope they can find sound. All under Warranty. Thanks

MTPZ06

Was the shop able to diagnose?

redbird555

Most likely the ac compressor mine does the same thing. Did you disconnect the ac belt as well? Rev it with the ac on and listen close then turn the ac off and repeat...I'll bet money it goes away

r2boxers

I did disconnect the belt and the noise was still there. My mechanic could not diagnose. It has since stopped making the noise. A 2-3 day problem. So glad it went away, whatever it was.

redbird555

Did you disconnect the ac belt or just the main drive belt there are 2

r2boxers

Ahh, you got me on that one. I did not disconnect the A/C belt. Now that I think about it, the air conditioning was on when noise would occur. Could only hear it with the hood open. This all makes sense now! Thanks for your input. I can now put this mystery to bed.