I'm getting a pronounced 'ringing' sounds for the lack of a more descriptive word, in my '88 4Runner starting at 4300+rpm. It only does it under load but can't reproduce it when parked. It almost sounds like belt slipping but a little harsher and more well 'metallic' sounding. (original belts were replaced a couple years ago w/ new Gates)
It's a 5 speed - has about 140K miles, timing chain replaced about 25k miles ago, generally kept in a good state of tune. I've tried it w/ the AC off and on and no affect. Alt is original.
Water pump is original. I can feel a slight (and I do mean slight) movement in the fan - not sure if that could be the cause or if it's from the fan clutch or the water pump shaft. Bottom line is that maybe nothing - not sure.
Any suggestions on where to start?