Serpentine belt has me stumped

[marriedmanw]

Thanks for the suggestions that I've recieved on my other post about the serpentine belt. Background: Recieved a chirping sound with new MotorCraft belt, and shop advised to replace belt tensioner. Replaced belt tensioner and chirping remained. Changed the motorcraft belt with dayco belt and all quiet for 3 weeks then sqealing/chirping returned.
Which brings me to today. Removed the dayco belt and noticed the edges were worn in spots. I can see the seam (white seam) on most of belt but in two places there are flat spots where I can't seem to see the white seam. My thoughts are if the belt is rubbing or a pulley alignment wasn't correct wouldn't it rub the entire length of the belt?
The chirping with the Dayco belt will go away after driving for 20 minutes. Put the motorcraft belt back on and still chirping regardless on time driving. Following another thread they resolved problem by putting on goodyear gater belt, but I don't want to ruin belt if pulley isn't alligned or belt seams will rub off. How do you test pulley alignment?
I've had this vehicle for six months now and it's really becoming a PITA, but I can change a belt in less than 5 minutes now.
Thanks.

 

[98 ranger xlt]

Pull off belt and spin each individual pulley.

 

[BRUTUS_T_HOG]

sounds like you have a problem with your a/c compressor.. is it an occasional chirp or a constant chirp?

 

[AllanD]

there is often more than one belt that'll fit and if the belt is the size 1/2" longer

say a 68075 instead of a 68070 you'll get a chirp on engine start
when the alternator field energizes.
The reason for this is because of Hook's law
simply put spring tension is cumulative.

the slightly longer belt is more easily installed because the
tensioner doesn't need to be retracted as far, but because
the tensioner is almost fully extended in the normal position
there isn't much tension on it.

so what I'm suggesting here is that you may have a new belt,
but do you infact have the CORRECT belt?

AD

 

[marriedmanw]

Thanks for the replies. I've removed the belt again and each pulley will spin freely, but I noticed that the PS pulley will move in and out a little, but mechanic at Ford dealership said that's normal. I suggested the harmonic balancer and he thinks that is a possiablity. I've tried three different belts and each on once installed is tight and the tick marks on the tensioner line up. What has me stumped so much is the flat spots on the belt in about three places on the side of the belt. Whichever pulley has a wobble must be constant since it's not the entire length of the belt being hit.
Engine: 4.0L SOHC Vin: E

 

[sdfishman]

Goodyear Gatorback belt is the serpentine belt to get. I changed everything and it ended up being the belt. Clean your pulleys with carb cleaner and a toothbrush before you install.. LMK if that works. I ended up changing everything tensioner pulley/idler pulley/fan clutch/alternator/water pump and it was a defective belt..

 

[BRUTUS_T_HOG]

if you think a pulley is wobbling then you can get one of those dollar store laser pointers and shine the beam on the very edge of the pulley. you can detect any run out with this method

 

[jcam8]

had my truck for less than two months and the infamous chirp came. after two years of dealing with the noise i think i finally found the problem and i'm gonna share everything i've learned/heard as i went about it. I went through 2 alt., 6 or so idlers, probly 4 belts, water pump, steering pump, and one, maybe two tensioners. the stealership said they replaced the tensioner, but that was the same time they left my radiator cap off, air intake tube loose, and an air return hose off, so who knows. anyways, a local mechanic found part of the problem, the threads on the bolt that holds the idler in were cross threaded. problem was fixed for about 9 months then i went puddle bustin and the problem came back. same mechanic replace the idler and belt with ford brand, NOT MOTORCRAFT, but ford. problem fixed again for 5 months or so. came back again and no one could figure it out so i just thought i'd drive it til it seized up then i'd know for sure what it was. that got too annoying so i took it back in and still no one could figure it out. i did find tho that holding a wire brush to the ribbed side of the belt solved the problem for about 5 minutes. i then noticed that my steering pump pulley had a chip in part of the ribs. i thought that could be it, but a few buddies suggested the tensioner instead just b/c it wobbled kinda funny. after lots of research, i installed a gates brand tensioner yesterday. no noise yet. hopefully we can stay that way. let me know if i can be of any help with this problem. i chased it around fro 2 years so i know my way around the belt accesories pretty well on the 3.0liters.

 

[Jetinspector]

I ran into the same problem with my 93. The belt called for is to long by about 2cm. Replaced it with a belt for a later model and the problem went away. I also did a tensioner with a new belt as some have done here. The original tensioner was ok the belt just was to long. I noticed the chirp every time the A/C would come on.
Denny

 

[88_Eddie]

i didnt bother reading the other posts on this thread cause they're kinda long, but when you buy new belts, they sometimes squeal until they get broken in. spray a dab of wd40 on one of the pulleys, if that's the problem, then the squealing should stop, if it keeps chirping, then it's something else.