Whirlpool/Kenmore Dryer Idler Pulley Squeak
For a few years Whirlpool decided to try using a different style idler pulley (belt tension pulley) on their 29″ wide dryers with the lint filter located on the top of the dryer. They did this for about 2-3 years, and then they decided to go back to the original idler pulley that they had used for years previously.
This poorly designed idler pulley uses a piece of stamped metal with a plastic/teflon piece attached to it where the belt rides to reduce the friction. Over time this idler pulley will start to make loud squealing noises or even high pitched whines. Sometimes the squeak will be louder when the dryer starts, and then go away. Whirlpool has now gone back to the original design that uses a wheel that fixes this squeaking noise.
Bad Squeaking Idler Pulley
Part to fix the problem. Part Number PD00002256 (mfg #691366)
For a little bit more you can get a maintenance kit part number PD00002464 (mfg#4392065), that includes the idler pulley, belt, and rear drum rollers.