Noise coming from somewhere in the serpentine setup.

Replaced the idler pulley, it was a little rough. Tensioner feels fine.
Wash about to pull the fan clutch off when the noise stopped for a week.

It's back. Now I'm leaning towards the power steering pulley / pump, although I have no troubles with the steering otherwise.

Any tips on how to isolate the problem source?

 

Describe the noise, screetching and squeeling? Put the belt under a load I.e: turn the steering wheel and have the engine in gear and hold your foot on the brake. This puts a load on the belt from the power steering pump. If it squeels then your tentioner may not be putting enough force on the belt. Does the belt wobble or operate in a straight line? Is the belt cracked or missing ribs? Could be time for a new belt if its cracked it is dry rotted like an old tire and doesn't grip the pulleys like it should and it just slides over them causing noise. Hope this helps. Tell us the noise its making , thanks

 

Also remove the belt and rotate pulleys seperately . The idler tentioner and alternator as well the water pump. The water pump should have resistance such as rotating one revolution then coming to a stop. If not its loose and sloppy and worn out. May be causing the noise as well

 

New belt? No? Replace the belt, and clean pulley surfaces.

Goodyear Gatorback serpentine belts work good or pop for Motorcraft OEM

Belt.



What year and mileage on the truck?

 

First, try spraying the belt with liquid soap. Dust on the belt will make a loud cracking sound, or even a screech.

 

Gatorback belt in good condition. Idler pulley replaced. Tensioner pulley is fine.

Noise is an occasional high pitched squeak and sometimes evolves into a solid low grind type of noise.

No noticeable change in noise when steering wheel turned, no noticeable drag on steering wheel or engine when noise occurs either.

Water pump was replaced a year ago and fan clutch about 150K ago. AC and PS are original.

Noise sometimes disappears for a few days, then returns and is constant.