XJC89 ...Haynes should've talked to YOU before publishing their manual on F150s!
Maybe i should call them up, i dont think there is any repair information in the haynes manual for the IWE, it just describes it but doesnt show you how to replace or repair it.
When i replaced my lines i used regular rubber lines and saved some of the original lines for patch work. I didnt buy any hard lines. One thing i did was saved the double line that comes right off the IWE actuator, because there are two connections of the actuator, the big one is the vacuum line the little one is the vent line. I then used a razor blade and split the double line so i could reuse the vent line cause its quite a bit smaller. But im sure you can buy some of that size hose as well.
To see if your IWEs are disengageing while your in 2WD is very simple. Make sure your in 2WD and then just jack the front of the truck up so the tires are not touching the ground. Turn the truck on, then go back to the front of the truck and spin each wheel and see if the half shafts turn with each wheel. If they do not turn then you are good to go, if they are turning then they are not releasing. Give the truck a couple seconds from the time you turn it on till you spin a tire, it takes just a few seconds for the vacuum to build and replease the actuators. Usually by the time you start the truck and walk back to the front its enough time.
Another way to check if the actuators are disengaging is do what i did. After i replaced all the line i cut the line that comes out of the solenoid about half way between the solenoid and where that line spits to go to each wheel. I then put a T in the line, and use it as like a diagnostic port if you will. i connected a long peice of vacuum hose to it and ran it out from under the hood up by the passenger side cowl and then in through the passenger side window, i then connected my vacuum guage to it. This then gives me the ability to watch the vaccum while i was driving. This helped after i replaced the actuators and still got the grind cause i was able to see that while under load i was loosing vacuum to the point where the IWEs tried to engage (which is what everyones does when it goes bad, load equals low vacuum, thats what the check valves are for to hold the high vacuum while under load to keep a continuous high vacuum scenerio) This testing capability will show you exactly where your vacuum is while driving. Then when im done testing i disconnect the extra hose and plug off the T in the line. This gives you a real good feeling of how the system works, you will see you vacuum build up when you turn the truck on, and if you have a leak, you will see it drop and as soon as the vacuum hits 5 bar, you will hear the grinding and see the guage start jumping.
Then after you turn the truck off, you willl hear a quick pssssssssss, a couple seconds after you turn the truck off. Thats the solenoid releasing the vacuum which locks the hubs in. At this point with the truck off and vacuum released if you spin a wheel you will see the half shafts turn.
JWILLY....The CV boot does not (in my knowledge) hold any vacuum from anywhere. So no, the tear will not effect vacuum whatsoever. But what the tear will do is allow moisture and dirt to enter the boot where the grease and bearings are located. After some exposure, the contaminates could damage the bearings and break down the grease. If you are going to tear down the one side to replace the IWE then i would replace that boot as well, you will already have that all apart anyway. Or if you take it somewhere just have them do it as well. A couple dollars now for a boot is alot better than a lot of dollars later for all new CV bearings or new half shaft.
I told you, your grinding would go away after you disconnected the lines. Now you need to troubleshoot everything with a vacuum guage to determine if the leak is a bad IWE, hose, check valve, solenoid, or vacuum tank. A leak in anyone of those can cause the problem your experiencing. Good luck. And read through my very first post in this thread for testing.