Great thread! It took me a few days to read through it and started looking things over this evening.

My issue started when I would attempt to put my 08 Expedition EL Limitted into 4x4 auto or 4hi. When I move the rotating switch on the dash, sometimes I get no indicators on the dash. Other times the display will read "Shift in Progress" then it will go away with no further indications. The very first time I tried "4 AUTO" (bought it used a few months ago with >102K on it), I got the "shift in process" notification then "AUTO" in the notification center. Since then it will not progress from "shift in process" to "AUTO" or 4HI.

I raised the front off the ground tonight and the half shafts both spin with their respective wheel when the engine is off AND with the engine running in 2HI. With the dash switch set to 4A, same thing, both half shafts will spin with their respective wheel only. When I put the dash switch into the 4H position and try to spin a wheel, the half shaft spins and the oposite side half shaft and wheel will rotate in the opposite direction (based on experience with open diff RWD cars, I think this last observation is appropriate).

Back on the ground, if I put the dash switch into the 4L position, I wll here the transfer case cluncking into gear and the 4LO message will appear on the notification center display and it will "crawl". I have not been able to test if the front wheels are being driven in 4LO, 4HI or 4A.

I tried rapping on the transfer case shift motor and when I took it for a test drive and switched to 4A. The message center read "shift in process" and then for a brief instant I saw "AUTO" flash in the message center on the dash but then it went away.

However, it's freaking cold here right now in northern IL so I called it quits for the night. I'll try hitting the transfer case shift motor again tomorrow after work if weather permits.

Either way, I'm thinking I need a new transfer case shift motor as one step.

I also figure I need to trace down a vacuum leak but the solenoids are not on the firewall on my 08 Expedition that I can tell, I don't see them anywhere else unless they are buried behind some other stuff and I didn't allow time for a full on assault on the 4wd IWE vacuum system this evening in my cramped garage. I have a vacuum gauge burried in the garage somewhere to start testing the lines when I give myself a little more time.

Does anyone know where I might find the key parts of the IWE vacuum system on an 08 Expedition Limited including the solenoids, check valves and vacuum canister that have been mentioned in this thread?

 

So I got all four wheels off the ground.

In 2H, all 4 wheels spin, though the fronts spin slower than the rear and I can stop 1 front wheel with my foot.

In 4A, same thing. All 4 wheels spin, again, front slower than the rears. I can still stop one front with my foot.

In 4H, front and rear wheels spin at the same speed. I can still stop a front wheel with my foot but it takes more pressure.

In 4L, they all spin at the same speed (though different speed than 4H).

Weather was too rainy to dig into the IWE vacuum system this weekend but at least I know I should have all wheel or full 4 wheel drive if necessary going into the winter.

 

Ok, so I have read through forums on several sites now and I know I sound like a broken record, but I have not read anything to describe my problem. LOL. I have a 2005 screw FX4. In the last 6 months I have replaced the alternator, battery IWE solenoid and both IWE actuators. I have not read anything to describe how the electrical system is tied into the vacuum system. I will be driving down the road and experience the clicking/grinding noise that everyone else hears, but at the same time my battery light comes on and the amp gauge starts climbing higher. When I pull over the clicking stops and eventually the battery light goes out and the gauge returns to normal. Any ideas would help alot. The dealership tells me that the two issues cannot be related, but they always happen at the same time. Thanks again

 

Hello,

great Thread here.

I also have some problems with the vacuum lines.

In 2013, my shop replaced the IWE, some vac lines and the solenoid because I was unable to engange the 4x4 of my 2005 King Ranch. (costs appox. 1500€ in 2013)

Now since last summer, I recognize the grinding noise of the IWE again. But just when I tow a heavy trailer like my boat or the camper. When driving the truck without trailer/heavy load, no sound from the IWE. The 4x4 works currently normal. I can engange and disable the 4x4 like it should be.

Now I put an vacuum gauge in the vac line from the solenoid down to the IWE's and I observed the following:

- Engine OFF, I can create a vacuum with the pump of the gauge and I holds it for more then 15 minutes without loosing any VAC in the lines between the IWE and the solenoid.
- VAC when engine IDLE 23 to 24 (created by engine)
- VAC when accelerating up to 4.500 rpm dropps to 21but goes back to 23 when I stop to accelerate.

So, without trailer - everything is fine - no grinding noise. But with trailer, I can drive some miles/km until the noise comes back. When I hear the noise, I switch to 4x4, wait some seconds and then disable 4x4. The noise is then away until I it comes back after some miles. It comes back faster when I have to climb up a hill.

I have to wait some weeks to test the VAC line with the gauge and a trailer. Right now I dont want to mess up my camper/boat in the winter weather.

But do you have any suggestions what my issue could be ?!

BR
Michael

 

perhaps this has been mentioned in this thread, but the solution to my IWE problems was the vacuum reservoir box that resides in the fender behind the battery.. mine was cracked and busted:




new one from the local stealership and it has been all good since.

 

Hi, I have been lurking for a while, mostly due to IWE issues over the years but I finally needed to ask a question that I hadn't seen before. This is a fantastic thread, very helpful, so if I missed someone else asking this forgive but Is there an alternative to a Vacuum based hub locking system??? I know for older Dodge trucks there was an aftermarket electronic wheel locking system you could replace the vacuum system with, does such a thing exist for F-150's??? I have replaced 2 actuators and 3 wheel hubs over the last 8 years and 4 IWE solenoids. After every repair I get good vacuum, everything is great then inevitably I will start hearing the hub trying to engage going down the road, flip the dial into 4WD flip back....I do this for afew days until I can get to the garage and most times I have caught it before any damage, sometimes not so lucky...This is insane!, I know in the automotive world vacuum system have been used for a ton of things(after all engines are just big pumps someone once said...) But come on is 2015, I know the flying car thing hasn't worked out but could we at least get a electronic 4WD hub engagement system if Ford is going to insist on giving me nothing more than a dial on the dash??? Anyone heard of anything like this?

 

YES, I HAVE! And i know the solution!

There are a bunch of one way vacuum valves in the lines to the actuators. I think they are before the IWE solenoid. There is a maze of vacuum lines up against the firewall that lead to the IWE solenoid. There are (I think) three little circular vacuum fittings in two of the vacuum lines. These are one-way vaccum check valves.

The system works by always applying vacuum to the hubs in 2WD, In 4wd, the vacuum is released, and the springs in the actuators engage the hubs. in which at this point, vacuum builds behind the IWE solenoid, readying itself to retract the hubs, You turn the dial back to 2WD, one of the solenoids engages to open the lines to the wheels to and the other solenoid applies vacuum to suck the hubs out of engagement. Once the hubs are out of engagement, the 4wd controller (yes there is a box for the 4x4 control) closes both solenoids. This is where the check valves do there job, or in your case, don't do there job. They keep the vacuum applied with out the truck needing to be running. if they can't keep them disengaged, they grind. High vacuum situations (such as slow driving, or idling) will keep them disengaged, but when you step on the gas, vacuum goes down, allowing the actuators to partially engage. (i.e GRIND).

with the check valve problem, the temporary solution is to disconnect the vacuum at the wheel, and drive with the hubs locked until you can get the check valves fixed. If you don't, this continued grinding will ruin another set of actuators.

If they engaged when you shut the truck off you could never tow the truck from the rear if it died, you would be dragging the front drivetrain.

The test for this is to lift one wheel off the ground after it has sat overnight. (allowing the vacuum to bleed off due to bad check valves) if you try to spin one wheel and the front driveshaft turns, the hub is engaged, and you have either a vacuum leak, or a few bad check valves.

The parts to fix from ford are EXPENSIVE for the stock piece, as you can only order the WHOLE vacuum line assembly. You can't buy just the check valves from ford. (and, to make matters worse, they are kinda integrated into the vacuum fittings, making singular replacement difficult.

My suggestion is to take the 4WD vacuum line assembly off the truck, recreate it with vacuum hose, and find the check valves of the right size to fit whatever size of vacuum hose you choose. there are a few manufactures of these, and you can probably find them on ebay in the sizes you need. 1 hint, the first one is on the firewall and comes off a 'T' fitting from or near the brake booster. This one is the MAIN Vacuum feed for the 4wd system.

To test the check valves, suck on one end, then blow thru the same end, If it works properly, and seals tight, you will only get air thru one direction.

Edit, thinking out loud, if all the check valves are good. and you've verified no vacuum leaks at the solenoids, Inspect the hard plastic lines to the wheels. Test those end to end with a vacuum pump, see if they hold vacuum (21 inch/HG) for LONG Periods of time.. like an hour or more.. if they fail, replace with new parts (not cheap either) or run new soft vacuum hose to the wheels.

To answer your last question:

No, i have not heard of any alternative to the vacuum system, other then my opinion that someone needs to design an actuator that uses vaccum to engage, instead of disengage. At least if it doesn't engage, I'm not stuck turning my front drivetrain until repaired.

The real solution is AWD. AWD systems have a viscous coupling in the transfer case (think torque converter). This allows all the wheels to spin at different rates without damage. (the reason your not supposed to run 4wd on dry pavement). Your auto setting just engages 4wd when it senses one or more wheels going slower or faster then the other wheels, ( senses the tires slipping) then programming kicks in, and the system makes a decision to engage 4wd or not. You never know when it does or doesn't. it doesn't tell you.




Good luck,

 

Dorman makes replacement check valves that fit, got them at Advance Auto for less then $2.

 

they do NOW... in 2008 when I had my 04 F150, Nobody carried them.... I had to scour the internet to find a place, and ended up ordering samples from a manufacturer. ( read: FREE SAMPLES and I chose the sizes)

 

Ok, now that makes sense. I am, well, a bit of a lead foot, and the fact that you say under heavy throttle the vacuum issue will raise its head now makes absolute sense. And yes I have noticed that my hubs are locked in the morning when I go to leave, have to do the whole shift into 4x4 and back down a side street before I pull into traffic. Ok, so check valves, ugly little gremlins...

 

I would also check the hard vacuum lines to each front actuator, the may be cracked also.

 

this is a very good post I have been having a noise problem with front end and this write up explained a lot thanks

 

I am having this problem and an out of town. I called 4 garages and my last choice, the only one that could get me in, was the local Ford garage.

They had it for 2 hours, could not find a leak. They also could not get it to grind.

However since they fooled with it (5 days ago) it has not tried to go in 4WD. When it was doing it I found that if I put it in 4WD the noise would stop. Can anyone tell me if that helps diagnose what I need to do ? Thanks

 

Yup, If you put it into 4wd, and the noise stops, you have a vacuum leak. It could very well be the actuators thenselves that are leaking. I only ever had one actuator go bad. When I got it off, you could see the tear in the rubber diaphragm of the actuator. It would not hold vacuum either. Get a cheap vacuum tester. connect directly to the actuator at the wheel end. if you can't hold 20-22hg of vacuum, the actuator is bad.

 

Is that something that the Ford garage would likely have tested ?

It has been a week now since they looked at it and no noise since. Can you post what an actuator looks like and where it is ?

I do not do my own work, but it would help my local mechanic when I get home.

Thanks much.