2001 f150 super crew 5.4 squeak
 

Ok guys about 7months ago replaced cerpentine belt on my 2001 f150 with 5.4 due to squeaking/squealing. Once I replaced belt noise went away well about 2 weeks ago noise can back(squeak/squeak) squeaks at idle when given throttle squeals not terribly loud. So I removed cerpentine belt and checked pulleys idler pulley and tension assembly where questionable and the alternator when I turned pulley squeaked. So I replaced idler pulley tension assembly and put a new starter on it and 7 month old belt back on noise went away put 200 miles on the truck last weekend. Truck has set for a week and when I started today squeak squeal again once truck completely warms up it goes away any ideas?

Try a higher quality belt or find the pulley. That's about all we can tell ya. Nothing else you can do.

Thanks for the advice tackle with the idler pulley tension assembly and alternator replacement how do I check other pulleys I guess cheapest and easiest would be replace belt with higher quality as advised and go from there?

are there any pulleys with rust on them? Mine did the same but I replaced the one with a little rust on it quiet as a mouse now.

Spray wd40 or water on the back of each pulley one by one. When the noise goes away, focus on that pulley.

If you spray the belt and it goes away, replace the belt.

Or pull the belt and feel the other pulleys. If they wiggle or you hear grinding when spinning, replace it.

Or use a automotive stethoscope on each pulley with the belt on.

You'll find it.

I haven't noticed any pulleys with rust but I can double check and try with stethoscope I also noticed should the idler pulley be able to be turned by hand cause with existing belt I can turn idler will by hand ?

Check the a/c compressor pulley. If the clutch is going bad, it will make some weird noises, usually when it's cycling on/off. Mine did it for a while, then one day, I shut it off, and when I tried to start it again, it was seized up. Ended up installing the bypass instead of replacing the compressor.

I don't know if this helps the noise doesn't change with ac engaged or not!

You said the alternator pulley squeaks when you turn it by hand....so that's part or all of your problem. It's going to make noise no matter what belt is on it. Sounds like the bearings are shot.

Had the same problem with my 95 diesel. Every 6 months i was replacing belts as they would start squealing. All the pulleys were good. Finally ended up taking a wire brush to all the pulleys with groves in them and cleaned them all up. All the flat surface pulleys i just took some 400 or 600 grit sand paper and cleaned them all up. Went 4 years on the last belt and still going strong when i sold it.