Squealing around 1250-1500 RPM

[TShockley]

I have a 4.0L 6 Cylinder 2007 Explorer Eddie Bauer that is about 40k miles. When I drive I hear a high pitched squealing sound. I have had this problem in the past but it had resolved for the most part, now I am starting to notice it on a somewhat regular basis.

While driving I am hearing a squealing noise that only occurs while accelerating and in the ballpark of 1250-1500 RPM's, when I accelerate any further the noise goes away. I’m not sure what gear I am in when the problem occurs or if it even matters. Given the frequency of the noise it seems almost clear that it is definitely something belt-driven. The noise is audible in the ballpark of 1250 RPM and gets louder as I approach 1500 then disappears between 1500 & 2000 RPM. I also have not been able to reproduce the problem when the vehicle is in Park.

Checked the belt and it seems tight, appears to be in good condition. I brought this to Ford once before when I first bought the vehicle a year ago and they replaced the belt. Tried to explain the problem to the service tech but they assured me there was nothing they could do without leaving the vehicle with them for the entire day.

Any ideas on what could be causing the problem?

Also, The first time this happened I realized that it worsened when I turned the wheel but for some reason it only got worse when I turned the wheel to the left. I dont know if that is just a passive observation or if it effects the drive system differently. Doesnt seem to be the case now though.

 

[Davidm53]

Could be the idler pulley and or the tensioner. They are easy to replace along with a new belt.
They can make a noise at different rpms.
Other possibilities, power steering pump, or the alternator.

 

[granadojl]

I concur with Davidm53. I just replaced my Belt Tensioner and the squealing went away. I also replaced the A/C Clutch, Coil, and Pulley Which were worn out which was also adding to the squealing.

 

[LONO100]

are you sure your belts are at the right tension? i would almost be certain it could be as simple as fiddling with your alternator belt tension until you can get it to go away. that or the power steering pulley. i had the same problem, couldnt figure it out. i just started playing with the belt tension on my alternator and boom, problem solved.

 

[TShockley]

Took it to ford more times than I can count now. Everytime I go they tell me there is nothing wrong and they could not replicate the issue. They replaced the idler pulley and said that it was "slightly loose" but that didnt fix the issue. As soon as I pulled off of the lot the problem started again.

What bothers me the most is that it is intermittant, there is no 100% scenario to replicate the problem. From what little knowledge I have on the topic the belt seems to be tightened sufficiently but I notice that the tensioner tends to "wobble" a little bit while at idle. The problem rarely occurs when the vehicle is idling but I wonder if that could be the cause when I am driving.

 

[Davidm53]

I went with Dayco on my belt,tensioner and idler pulley. Prefer Motorcraft but Dayco seems to specialize in belts and tensioners.
Working good for me so far.

 

[Brillig]

Could be the air intake whistling noise. Check out this thread:

http://www.explorerforum.com/forums/showthread.php?t=224034

Skip the parts about aftermarket intakes - some explorers, including mine, make this noise completely stock. It got a lot better when I had the throttle body cleaned. It's not too expensive, so it might be worth a shot for you.