1999 ford ranger 4 cyl whine?

Sounds to me like a belt tensioner or pulley that has a bad bearing or is glazed. A good friend of mine had the same problem for over two years. His wife took it to a dozen different shops, but after a couple hundred dollars he finally brought it to me. First, I verified the belt routing with the routing label on the truck, then I removed the belt. I started the truck for a minute and the noise was not there. This tells me the problem is ran by the serpentine belt. Next, I checked the pulleys for visible wear and glazing, also checked for play and rotational drag. The stationary Idler pulley had a lot of side play and the tensioner was twisted causing the belt to run on the side lip of the pulley. We double check the condition of the belt and it had no glazing or cracks. He spent about 40 bucks on a new idler pulley and tensioner assembly. Took about an hour to replace them and reinstall the belt. When we started it there was no whine and you could only hear the injectors ticking.

Before removing the belt, look down the length of it for any misalignment in the pulleys, That is how we found the twist in the tensioner.

Hope this helps. Christopher

Acording to the owners manual.Towing is not recommended with the 4 cylinder engine.