I have a slight squeak when my truck is cold. it definitely sounds rotational by the rhythm of it, and it is only slightly related to rpm, not related to speed. it is coming from the front of the truck. A/C on or off i still have it. After 10mins of driving it goes away, and if the truck has been sitting in the hot sun it doesn't do it. Usually, right in the morning when i pull out of the garage, or after work on a cold day.

 

this is still happening. Any ideas on how to diagnose? i believe i was incorrect in my above statement, sometimes i can get it to go away when i cycle the a/c on. the issue is i cannot drop it off at the dealership, by the time they open, the noise would be silenced.

can i just squirt some lube on the pully bearings on any fan belts?

 

May be the serpentine belt starting to wear, I would be hesitant about applying anything to the belt as it can gum up the pulleys and cause a bigger issue down the road. A number of years ago when I was a service advisor for a GM dealership, we would see people come in for a new belt that they applied belt dressing to (to quite them) and the techs would always have to use a wire brush and solution on the pulleys to clean the gunk off. 1/2 hour job turned into 2 hours sometimes.

Oil will not help the pulleys either, if you need to apply oil to the pulleys then the sealed for life bearings are starting to dry up and the pulley needs to be replaced (tensioner) and if you get any on the face of the belt or on the belt surface of the pulley then you could easily have an issue with belt slippage, A/C, Alternator, may not work properly if there is enough slippage.

Just my overly cautious 2 cents worth.

 

Had that exact problem on my 2018 5.0 L. It was a bad A/C compressor tensioner. Dealer fixed under warranty.

 

sounds good. unfortunately i do not believe the 2.7 has a tensioner for the A/C belt

 

Yes it does, I just replaced the tensioner and belt on my 2.7. Single belt drives it all. At 127K the belt was becoming brittle and very small cracks through out the belt
It sounds like it could be a belt squeak to me.

 

little difficult to hear as it was really warm this morning

 

gotcha, you are correct. the 3.5 does not have a tensioner and separate belt.

 

took truck to dealership to get oil change. they confirmed that it was the tensioner pulley, and they suggested replacing the tensioner, idler pulley and serp belt. $466. At 50k mi, I would not expect to be replacing serp belts and tensioners already....but here we are.

 

$130 in parts if you buy all Motorcraft. Three bolts, can't imagine it being very difficult, but I've been wrong before.