I've been trying to diagnose a ringing coming from my engine without any success. Please help!
It's been raining here for the past few days pretty hard. When the rain first began, my car started squealing / ringing. I thought it was just the belts and it would go away with the rain but it didn't and now it's louder than ever. I did a search on here and came up with a rain-squeal but that's not it. It's loudest while the car isn't moving.

Here are the symptoms:

1) Ringing starts after car warms up.
2) Loudest when parked at idle
3) Under load it quiets down and at cruising gets louder
4) Adjusting heat / AC has no effect
5) Pushing in clutch has no effect
5) Searched engine compartment with a screw driver to the ear and a tube to the ear and couldn't find source. The ringing is a seriously strong harmonic and gets loudest in different parts of the compartment on opposite sides and then gets loud again if I set back 3ft from car. If not annoying, its very interesting.
6) Check engine light came on: checked OBDII codes and only one came up: running lean at idle

The only other thing that is going on with my car and started at the same time as all of this is that the driver's foot space just flooded for the first time with water from the rain. I think it is from a drain tube from the sunroof. Could this be correlated in anyway? I doubt it but I thought I would through it out there.

Thanks for any and all comments, I need serious help on this. Here is the stats on my car:

2005 Volvo V50 T5 AWD 6spd std - 70k miles
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- Mike