Have you actually tried the method you describe about unhooking the actuators from the vacuum lines and letting the actuators spin with the front diff., or is it just what "looks like it should work" based on a drawing up of the system?

there are only two positions... vacuum ON and the IWE pulls off and you are in 2 x 4... Vacuum OFF ( or remove hoses) and the IWE should engage and you are in 4 x 4.. if you hear grinding, then the IWE is not working correctly and is sticking.

 

This is a known fact, that people have actually done physically, not just "that's how it is designed to work" type of reporting after reading about the IWE system?

I ask because in 2wd, the vacuum pulls enough to drive short distances around town and coast while not pressing the throttle, and if I switch to 4wd there is no grinding at all (and if there was slight grinding from driving under throttle in 2wd for a while, it goes away if I switch to 4wd). So it's hard to believe that the reason for the grind is that the actuator is sticking. The slight grind over time that I am hearing from the wheels in 2wd seems most likely due to a vacuum leak (one of which I did find, so there is possibly a smaller second vacuum leak somewhere in the system).

Since the 4wd works as it should without grinding when everything is hooked up, I am finding it hard to believe that when the hoses are disconnected from the actuators that the very loud instant grinding I am hearing in 2wd is due to bad actuators being stuck and not fully relaxing into the hub.

Maybe I am misunderstanding something, maybe no one has really tested this, maybe there is something deeper that is wrong with the 2wd/4wd system of my truck, all I'm saying is I'm reporting what I am observing with live testing and it's not making sense to me vs what people are saying here without stating they actually went out and tried to drive their trucks in 2wd with the hoses disconnected from the actuators.

UNLESS, after unplugging the hoses from the actuators I need to do something like shift to 4wd to "lock things up right" then switch back to 2wd and go on my way. I don't know, I'm trying to figure out some reason why I am not experiencing in person what people have said here should work to stop grinding in 2wd...

 

I'd guess that the gears on your IWE ends are already damaged and are only partially engaged, which is causing the grinding noise.

One way to confirm this is to jack up each front wheel, leave the engine off. Spin the tire & see if the axle spins. If the axle doesn't spin with the wheel then your IWE actuator needs to be replaced.

 

I would agree with you except that when everything is hooked up 4WD works with no issues of grinding or anything - everything is engaged and working.

Have you taken the vacuum lines off your actuators and tested to see if that method actually works for full engagement without grinding in 2WD?

 

I told you how to check it - engine off, jack a wheel, spin the wheel.

Does the axle turn with the wheel?

 

Each side half shaft spins with its wheel when truck is off. When truck is on at idle each wheel spins independent of the half shaft. Everything works fine. It's a slight vacuum leak that is my issue.

I also gave you (and others) a suggestion about how to check the "hoses off the actuators" method, since no one seems to want to say they've done it in real life and only that in theory it should work. Did you try driving in 2WD with the hoses off the actuators?

 

put it in 4x4, engine off or on, in park, & try again - are they locked solid (can't turn the wheel)?

I'm not about to pull the vacuum off of my actuators and drive around in 2wd, I've already replaced mine a few times and I'll be happy if I get through the winter with 4x4 still working.

You didn't pack a bunch of grease at the hub/IWE interface did you? I think that's what caused my repeated problem.

 

Thanks, I'll try this, didn't think to see how well they are locked solid against my forceful attempting to spin them.

Ah, so you at least admit that it's not good for the actuators

This could also be my problem, though I'd like to think it's doubtful. I did use "some" grease to lube up all the parts, but for my first (and second if you count both sides) job doing it I was afraid to use too little. I wouldn't think I used too much, only put on a gloved finger and rubbed it around all over the place.

I know for sure I still have a slight vacuum leak (CEL and gaining noise in 2WD when going down the highway for >2-3 minutes tells me so), but if the actuators are also ground down some then I'd like to get that taken care of as well 1) while the parts are still warrantied and 2) while it's not below freezing outside.

 

Have you even read the sticky?

https://www.ford-trucks.com/forums/8...then-some.html

 

Ok. Ok. You win. Actuators (both sides) are still on warranty so I guess I'll be changing them out next weekend when the new ones arrive. I also guess I'll be capping off the vacuum at the manifold (or slightly downfield from it) and just run the truck with the actuators always engaged. 1-2 mpg loss isn't a concern. I can afford the 7% rise in fuel cost as long as the 2wd / 4wd system works without grinding out the gears.

While I am at it, any concern with the gearing in the hub assemblies being ground down like the actuators? Those are both still under warranty as well and I'd like to get everything taken care of at once in one long painful day if I can.

 

I don't think I'd bother with the hubs. Read the rest of that though. and then go through it again.

I took a bunch of brake or carb cleaner & an old toothbrush & scrubbed out the gear faces, then just use a real light amount of grease (tub/tube), maybe as much as the last knuckle-to-tip of your finger (like a fat toothpaste squeeze amount & rub it in). I went probably even less than that on the very last time. I'm going to do all the vac checks on mine soon, it's a little more clear to me after reading it again.

 

Hopefully the final post re: this problem I am having.

Replaced driver actuator (again - under warranty so no cost just time), axle spinning with tire, so all good there.

Replaced passenger actuator, looked at hub assembly gearing, it was chewed almost to nothing, checked with new actuator, tire spun half turn with grind noise, no axle turn, put broken actuator back on until I could get another hub assembly in (assembly and actuator parts both warrantied so no cost again, just more time).

New assembly came in, replaced both assembly and actuator with the good new parts, axle turns with tire, no grinding, put everything back together.

Left the vacuum hoses disconnected at the actuators and also disconnected the vacuum connection at the first check valve (valve closest to the engine) and plugged with rubber cap to leave the actuators engaged all the time (what I've been calling the "Live Axle Mod" since I couldn't find another way to describe it).

Test drove around, no grinding. Tested on highways, no grinding. Should be good to go now.

HOPEFULLY this will keep me from grinding gears out on hub assemblies and actuators, as well as correct any vacuum leak I still had related to the 4WD system, and also give me 2WD (with live axles) and 4WD when needed in winters.

Side note - replaced the transfer case motor while I was at it (another part previously replaced with a warranty so no loss in cost there either). Didn't "feel" like it was engaging with the click/thunk that it's supposed to have when engaging/disengaging, so I replaced as a precaution. Infinitely less difficult than the actuators and hub assemblies, so no big deal to throw that on top of everything else today.

...on to the next fix...

 

never give up!