91 accord making whistling sound; battery light

I have a '91 Accord LX sedan. Today, it began making a steady high-pitched whistling sound from around the engine. When I turn the ignition off, it continues to make the sound for 2 seconds, then smoothly dissipates in 1 second with a final sucking sound. Then, it's done.

Also, two days ago, I gave a friend a jump start. I did not hook the negative cable up to her car's engine, but rather to her car battery's negative terminal (positive to positive, negative to negative). Her car started up and everything seemed okay, but that same day my Accord's battery (charging system) light started coming on at times. Today, it stayed on consistently for two 20-minute trips, but then went out and hasn't come on again in another 40 minutes of driving.

Thing is, right after the battery light went out for good today, I began to hear that faint whistling sound while driving that is quite noticeable with the hood up. Hadn't heard it before at all.

Any ideas on what may have happened, what might be causing these things to happen, and if these two are related? (The battery light and whistling sound, that is.)

All help is greatly appreciated!
Thanks!

chk the alt belt,, if belt is ok, could be a bad alternator..

it is hard to properly diagnose noises over the net,,so it has to be up to you, or take it to a shop to close in at what it might be ..

that noice could just be your intake note, that thump and the end when you turn your car off is normal though, its a compression release. the battery light...mmm not sure maybe your system has low voltage, which could mean your battery or alternator is going bad.


lightshow

Thanks for the responses.

Could the fact that I hooked up the negative cable to my friend's battery's negative terminal (and not to her engine or another grounded part) cause a short or other damage in my car's alternator or battery?

no it wont hurt anything to have black to black and red to red.