I have a 95 Bronco 5.0 with 70,000 mi. I get a high pitched whirring sound when it rains or is humid. It seems to be coming from my serp belt...it is in good condition. The noise is very loud at idle, but goes away when I accelerate. I changed the idler pulley, thinking it had worn a bit "square"...no luck. It does not make the sound in dry weather. Could it be a water pump bearing? Maybe the belt material. I changed the belt at 55K with a Ford Belt.

This is driving me batty!!!!!

 

[font size="1" color="#FF0000"]LAST EDITED ON 20-Sep-00 AT 10:03 PM (EST)[/font][p]Paul, try rubbing a bar of soap along belt, see if that makes a difference. Water pump bearings sound like that when they go bad, but pumps usually "weep" out the shaft hole before they go bad. If bearing is bad, the shaft will have play in it. Try moving the fan (or pulley) back and forth to check. Good luck. Don

P.S. Might be alternator bearing.

"Nothing lasts forever except natural stone and old Ford trucks." (Willie Nelson)