How To Weak Vacuum Line and grinding noise FIX

I've got a 2015 with 98k....just started the grinding at speeds greater than 75-80 and usually under acceleration. I've swapped the solenoid and have checked vacuum. I'm only getting the noise intermittently now...but still grinding. Any ideas on why it might be intermittent?

 

^ power makes it slip over the week gears in the IWE. you'll have to replace them also.

 

My 2018 F-150 now has 6k miles, started getting intermittent scraping noises at about 5k, which is pretty darned early in life IMHO. I'm off to buy a vacuum gauge and start troubleshooting. The dealer I purchased from is willing to take a look, but when I asked how he'd troubleshoot such an intermittent problem he didn't know. I suggested I'll try the shift-into-4WD-mode test to see if the noise stops and at least give him some info that is more valuable. (I didn't know about that test until this morning so haven't had the noise to try the test yet.)

Anyway, I guess my point here is that the symptoms can occur on an almost new truck.


Cheers.

 

Mil T -
I've read the entire thread and I have a question which, with your disassembly/re-assembly background, you might be able to answer. The sounds are described as either grinding, or clicking, or like cards on bicycle spokes. The noise I hear in my 2018 is grinding as if a brake rotor was rubbing on a piece of stuck gravel. If a partial hub engagement is occurring, why would it sound like grinding? I can understand why it would sound like clicking or cards-on-spokes due to gear teeth partially meshing, but why grinding? Is there an intermediate synchro ring in there somewhere that I don't see?

Thanks, just trying to understand a little more.
Ron