New here, and new to these 5.4 engines. My 2008 5.4 in a F150 Lariat SuperCrew is now making a lot of noise whirring or whining. Replaced the grooved idler that was rough feeling but no noise change. Ordered new tensioner and idlers. Any other possible cause? The power steering doesn’t change the noise going lock to lock so thinking it’s fine. TIA for the input

 

Does it whine if you pull the serpentine belt? If not, it is in fact one of the driven pulleys, use a stethoscope or a length of heater hose to try to localize which one.

 

I’m gonna try that Friday morning to see if that stops the noise. When I changed the other pulley I did start it and move it without the belt, but don’t remember if the noise was gone. Thanks

 

Fixed the noise. Went searching with the use of a dowel. The alternator bearings were toast. New alternator- no noise!

 

I had the same problem on my truck a year after I bought it. Only took 4 alternators to get it right.