I have a 1971 Dart Swinger with a 318. It makes a terrible screeching sound with the engine running. The noise increases as rpms increase. Sometimes the noise lessens as the car "warms up", but seems to be getting worse as time goes by (it's been doing this for about 3 years (~800 miles a year (summer cruiser))).

I've wiggled the water pump to see if there is any "play" in it. It feels OK.

Could the screeching sound be from the alternator? Maybe bad bearings? Any way to lubricate the bearings?

Any other ideas?

Pull the belt off and start it , if it's still there it's probably a rod bearing . Been there , got the shirt ...

pull one of the alt field terminals for 3 seconds as an electrical issue in alts (diode?) can sound like a scalded cat, rare but you'll elim that in seconds. If alt electrically is OK but pulling the belt quiets it yes you can grease the alt end bearings (assuming the pump vanes ain't touching). EDIT you might ground each plug wire & see if that changes the sound (rod bearing). Not sure if this is a valid test but it jogged something from way back & it's easy to do & I would try it (dont pull plug wires to do this as electronics dont like opens),stick a thin probe/wire in the dist cap in each plug boot then ground that wire (wear thick gloves )

you guys are saying a rod bearing would do this for 2400 miles over 3 years ???? HMMMM I would've thought it would've spun or started knocking long before that time ???

Was the engine assembled with the oil slinger on the front of the crankshaft? If it's not there and you're running a mechanical fuel pump the noise may be coming from the fuel pump eccentric burning up. The slinger is especially needed on a small block to keep oil thrown onto the eccentric and pump arm. Remember, you have steel rubbing against steel under spring pressure and it's pumping a non- compressible liquid (gas). It needs a constant supply of oil to lubricate and also cool the parts.

Thanks for the help everyone. I tried the simplest suggestion 1st (bar soap on the belts) and it worked!
Is there a more permanent solution? Some type of belt dressing?
to all

Replace belts with high quality belts. Lubricants are available however temporary relief at best and can be messy in your engine compartment. I have always used Gates as my belt of choice,,,there are others, just don't buy on cheapest price. In some cases 'notched' belts work better.

Also very important: Check alignment of all pulleys,,,out of alignment can cause screeching and/or belt throwing at high rpm, not to mention short life expectancy.

Also after you warm up with new belt re tighten it they stretch right away then seem to stay good after that.