2003 Ford F-150 Lightning Q&A

2003 Ford F-150 Lightning Question: Whats causing this noise?

My 2003 lightning has a high pitch whistling noise(sounds like a tea kettle) coming from behind the supercharger a little to the right. It only does it idling or when im at a steady speed but when I accelerate it stops. What could this be? -
Answer 1
pcv elbow may have a vacuum leak causing this. common issue with these motors. Roy -
Comment 1
Thanks and if not replaced soon could it cause more of a problem? -
Comment 2
it will throw a code eventually. i would get it confirmed asap. Roy -
Comment 3
where exactly is the pcv valve. is there a website i can go to? -
Comment 4
It is on the passenger side valve cover. There should be a sticker with a diagram under the hood. -
Comment 5
It was the elbow thanks but when I took the hose off the intake I noticed just a little oil, was the elbow causing that or is it something else -
Comment 6
That is normal due to wear in the pcv valve just replace the valve -
Answer 2
It sounds like a boost or vacuum leak -