On my 08 5.4 today there was a squealing noise coming from the drivers side injector, upper intake area. It didn't sound like it was under the valve cover. It was cold, 20° and I started it and drove it across the parking lot and it did it while idling. I gave it a little throttle and it went away but started again when it settled back to idle then stopped after a couple minutes.


Thoughts

 

^^^ FIFY.

Nothing in the intake will 'squeal'.

Possible culprits = idlers, tensioner, alt / PS bearings, etc.

Also - belt itself, spooge on the pulley surfaces ...

Remove serpentine belt temporarily - does squeal disappear?

If replacing belt use a Gatorback.

 

I was able to pop the hood and look at it while it was happening. im confident in the area it was coming from. maybe squeal is a bad description, maybe more if a hiss so high pitched it squeals. my first thought was fuel passing through something.

thanks!

 

Okay.

Sound is a funny thing - so much ambient cacophony under there. I can honestly say I've never heard fuel flowing through the injector rails.

You can, and should, rule out rotating components by yanking the belt - only takes a couple minutes.

If it still makes the noise, we can try to proceed from there. (vac hose collapse / connection / leak, PS fluid gurgle, etc).

Good luck! And yer welcome, lol!


MGD

 

You sure it's not the alternator whine? Usually happens at start-up then calms down and comes back at certain rpms.

Darren's old video from his '04:

 

true....but air moving through the intake passing over a CMCV that has come out of adjustment or stuck with debris....a long shot of a guess though....

 

Point.

I was going from the initially reported description of the sound.

Air leak in intake tract?

MGD

 

Thanks guys. I just bought an 2006 FX4 and had a whistling noise driving me crazy. I swapped the alternator and that fixed it. I never would have guessed. Thanks for saving me a ton of money time and frustration.