Too much vacuum in crankcase???
 

2005 f150 5.4l 3v
hello all,
my truck squeaks (chirps) from idle to 1500 rpm. It finally went away when my small breather tube chaffed and wore through. Once I replaced the tube the chirp was back. I have noticed when I take my oil cap off, I put my hand over it an it sucks my hand down pretty hard. I removed my pcv tube on the driver side and my truck won't even hold idle. What can cause this major vacuum?

It sounds like the PCV valve went south and is staying full open when it should not be.
There is a calibrated spring in the valve and it sounds like it could be broken, would pay to check it out and they are not that expensive, just replace it.

Thank you hanky.
My mechanic compared and figured that today. Saturday I will be swapping it as long as FOrd has one in stock. Thank you very much.

How'd you make out with that? I'm having the same issue with my truck, I replaced the heated PCV valve in the intake and it still squeels.