I’m trying to figure out what’s wrong with my 4WD and was testing the vacuum pressure. When 4WD was engaged there was absolutely no pressure at all, i know the idea is for pressure to be removed to engage it but should it be completely gone? When I put it in 4WD i can hear it click in but it just makes a grinding sound and never gives me any power so it seems like something isn’t engaging. Thanks in advance for the tips.

 

https://www.f150online.com/forums/ar...then-some.html

 

I’ve read that article a few times but can’t figure this out. So I jacked up the front and turned the wheels in 2wd and 4 hi/lo. The axles didn’t turn in any position. I unplugged the vacuum to the IWE’s and nothing worked and the axles didn’t turn driving like that either. Is the problem coming from my actuators/hub assembly or is it something not turning the front axle? I ordered the IWE (vacuum kill kit to take that out of the equation) and hub assembly to replace those first since I’m sure an axle problem is much more costly. Just looking for some thoughts and opinions on what people think it could be. I have a video of the sound of someone could help me better by hearing that

 

Also, when the truck was off I crawled under and could move the front drive shaft by hand. I heard the same clicking that I do when trying to drive while I was turning it by hand.

 

If all 4 wheels are on the ground, you should not be able to turn the front driveshaft by hand if the engine is off, 2wd or 4wd, or engine on in 4wd. Engine on in 2wd, you should be able to, and one or both axles should turn.