Long story short, I have a small vacuum leak in the 4wd system. I disconnected the lines going to the hubs to prevent grinding them to pieces as they are brand new. This, of course lock the front hubs in and disengages the X-fer case in 2wd.
It is not engaging in 4wd unless I select it, so I don't imagine it hurting anything in the X-fer case or anything. Other than the extra rolling mass, is this okay to operate at until I resolve my vacuum issue, provided I close all openings and places for trash to get in?
It's not going to hurt it for a little while...maybe a few hundred miles, but dont drive it like that for months. vacuum leak......common areas are inside the front wheel knuckles. They get water in them and rust where the IWE and behind the hub and bearing where the o'ring seals against the knuckle. The surface of the steering knuckle becomes too course to seal. Out a vacuum pum on each iwe while its installed and see if they hold vacuumm.
Basically, if you can switch into 4wd and the grinding stops, it's not too late. Best advice would be to do what I did and disconnect the vacuum lines from the solenoid. This will cut vacuum to the system and lock in the hubs. 4wd will not be enabled unless you select it. Then start diagnostics on the system
If it feels like the hubs are letting go when you turn in 4wd, the teeth may have ground out too much and you will need to replace.
But yes, vacuum and solenoids are a HUGE common problem. On some year models, the drip cowling would direct water directly onto the top of the solenoid, shorting it out. The vacuum system is a series of small lines and check valves that may leak. Also the hubs themselves can malfunction over time and not be able to fully lock in.
Your fine driving around with them locked in. I unknowingly drove around for months with mine locked in before i even knew what was going on, or that something wasnt right. Heck it could have been years for all i know. Mine never made the grinding noise, so they could have been shot and locked in when i bought it, and i never fixed the things for 2 years. After i fixed it everything else was fine.
I'm dealing with that now on my 07 F150 FX4 with 165,000 miles on it. Changed the solenoid and its still doing it. Can hear it on both sides. Just started last Sunday. Need to start troubleshooting lines in the morning.