Didn’t know if it was better to start new post or respond to one. Anyway, My 2016 f150 3.5 4x4 lariat with TOD 40k miles has been having Iwe issues. Battled my local ford dealer until I gave up because they couldn’t figure it out/recreate it. Unplugging my solenoid worked, took to a local mechanic to check everything (don’t know how thorough they were) but they found my front diff oil needed changed. I only use 4a/4h 4-5x/yr. So it shouldn’t need replaced if everything was working properly. Assuming my failing system was causing everything to rotate intermittently and incorrectly (partially engaged etc…)thus needed changed. They simply did ford TSB to block vacuum lines. My worry is that I already seem to have premature wear and don’t want front diff going out like I’ve read here. Also don’t want extra wear on other parts. Is there a way to apply permanent vacuum to IWE to disengage them. I was thinking if a valve could be installed that I could apply vacuum via hand pump then open valve when I needed it the 4-5 times per year. And then hand pump it back when I don’t. 99% of the time. Would be kind of like old locking hubs where I would have to get out and take care of it but wouldn’t mind that. Or if I knew I was going somewhere where I might need it then I could release it and let it spin and still use my on the fly 4wheel **** as needed.

 

It's up to you to fashion a new design.
The truck does exactly what you described -applies permanaent vacuum and has a valve that opens.
The valve in this case is the solenoid valve.
The problem(s) with the IWE design is to many parts if you wish to do what you suggest.
You already have a check valve, you could add a second one if it makes you feel better.
Get a small pump like a mitivac or Harbor Freight version and pull vacuum. The check valves will hold vacuum to the IWE while you remove the pump and probably add another level of precaution by plugging the hose.
Next in line is having a leaky vacuum hose. It can happen so you'd have to monitor that manually by bypassing the solenoid and any daily vacuum.
Next is the hose connection at the IWE, it may in time seep. You'd have to monitor pressure ensuring it has not bled off pressure.
And finally, sometimes an IWE fails internally, the vacuum escapes the IWE seals.

So if you wish to craft up a manual pump you will need to monitor the system ensuring no problems.
If you are out and about and you hear the rattle, you will need to 1) have your vacuum pump with you to pull vacuum and plug the line or 2) pull the vacuum from the checkvalves so both IWE's will return to the lock position so you can continue driving with locked hubs until you get back to your vacuum pump.

Unfortunately there are far too many diff failures in these modern trucks. Not sure if Ford spec oil is just junk but there at 40% of IWE problems that turn out to be a diff problems instead. No IWE issue whatsoever, just bad diff bearings. I don't know what was accomplished by the shop changing the diff oil (other than now it is fresh) but I wouldn't put too much thought into "now that my diff is fixed how should I proceed".


You may be able to simplify your design but having 2 independent connections (one for each wheel).
Get 4 check valves...2 for each line. Supply vacuum to unlock the hub and block off each of the 2 lines. Less connections and leak points this way vs having a Tee fitting and only 2 check valves.

The front axles do have a bit bit of drag even in 2h, those axles are always spinning while in motion to a certain degree. I don't think any of that would contribute to your differential problem.
I'd say 1) leave them locked per the TSB or 2) reconnect it like factory yourself. If you get one wheel (or both) that make noise, investigate why and fix the problem immediately so you can continue with the original design of the system

There probably isn't one answer better than other here.
-Craft up your own design to keep hubs semi-permanently unlocked
-Keep it as-is from the TSB/repair
-Replumb the IWEs and keep an eye (ear) out for vacuum problems.
I didn't care for the TSB (nor have many others) as their permanent fix. I'd probably ask the shop not to perform it if they told me that is what they were going to do. Sounds like you have enough knowledge of the system to maintain it yourself, which is probably what I would do if I were faced with that situation.

 

Thank you for the long thought out thorough reply.

I was dreaming up the manual valve solution for simplicity compared to the more complex system and multiple fail points that it is. This would help bypass any leaks in current valves, solenoids or hoses. But wouldn’t work if the Iwe seal is bad.

Like you and many others I don’t like their solution but given Ford and multiple other mechanics only have the tsb solution I was thinking it would be beyond my skill/time availability to tackle and keep reliable without constant attention/repair.

Once repaired is there any suggestion on keeping it working properly? Like turning on 4wd once a month to exercise things?

One of fords intial repairs was new check valve FL3Z3A788B. When I took mine off I wasn’t able to blow or suck air through it as it seemed stuck. It finally seemed to break free and seemed to function normally so figure maybe it’s wearing out. So I went and purchased it today. Price has skyrocketed $33. I think I read it use to be $9. Felt bad for the service guy after he looked for 20 min so bought it. Anyway I also read yg360 valve works too? Is this true or is this her another better valve?

In no particular order I figure I can check:
1) See if new valve helps
2) check if vacuum hold on lines to Iwe
3) check if vacuum holds at Iwe
4)read up on this forum on how to check solenoid
5) vacuum reservoir leak
Anything I’m missing?

If all checks out I might find someone to inspect and re-grease/place IWE. I think there was originally a tsb on needle bearing needing greased?

Is there any chance IWE engagement can help stabilize a bad wheel bearing? I was getting more noise when doing slow right turns and straight stops. Left turn pressure would make it go away. I originally thought bearings but the IWE engagement stopped the noise.

 

Sounds like you know exactly what to do.

The $9 valve is probably the YG part you mention. The hose/valve assembly is over $30. I paid around $34 for mine and it sits in the toolbox. I can't even use it since I no longer have the truck. ha
I installed it, I still had noises and removed the new part since old was working fine.

I only had the truck 2 weeks or less and jumped on the IWE bandwagon unnecessarily.

I went through all the tests and my truck passed them all, meeting the same outline as your steps 1, 2 and 3.

I used a vacuum gauge to check vacuum at the solenoid and I had adequate vacuum.
I provided vacuum to the system after the solenoid and I had no leak-down.
I provided vacuum at the IWE nipple and had no leak-down.

Vacuum in my vehicle was working just as it should. That convinced me that I wasn't having IWE issues but rather the noise was likely the front diff, based on the number of other failures.
IWE conversations seem to be quite common. However there are still a lot of folks similar to me, a properly working IWE system.

You could add a bit of grease to the needle bearings. I haven't heard of that one in a while so I'm not real familiar with why or what that was all about.
I don't know what you wish to accomplish by greasing the needle bearings though.
I wouldn't tear apart the IWE to add grease -if you are doing the work then just replace. There have been considerations that over-greasing could cause problems -the grease is too think for vacuum to overcome. So use cautiously if you do tear it apart to add grease.

Are you convinced you had IWE problems or is it possible it was an assumption to be an IWE but was not at all?
You had the typical 'rattle' sound? Descriptions include dragging a shovel behind you. Cans tied to a car like "just married".

 

To be honest not 100% sold on IWE issue. That’s why I asked if IWE engagement could stabilize wheel bearing going out or perhaps front diff problems. Because the engagement seems to make my noise go away.

I originally didn’t suspect IWE because it wasn’t the typical grinding. More of a whirring/binding rotating sound. Slightly reminded me of an old steering pump I had go out in a previous car. Acts up more in cold climate. Using 4wd would get rid of it and sometimes cause it to go away in 2wd for awhile but would eventually return. That’s why I asked if the system just needs exercised occasionally once fixed.

my symptoms only happen at slow speeds. Coasting or braking to a stop. Right wheel pressure increases noise (bearing?) Slow speed thing could just be because higher speeds drown out noise but I’ve tried paying attention and don’t notice it otherwise.

Another note is I have been getting a loud clang that just happens once after driving for a mile or two. Sound like sound kicking a tin can. Like there is something binding that releases. One time it did it and my noise increase significantly.

Sorry just kind of at a loss so that’s why I’m chasing the Iwe bandwagon right now.

thanks for you input so far

 

It sounds like I am having a conversation with myself.

My truck passed all the vacuum tests.
Only made the weird groaning sound in colder/cooler weather.
It was a warmer day the day I test drove it but not crazy warm. I bought on a Friday night. I think it was Monday morning when I pulled into the parking lot at work when I first heard this crazy noise.

It would come and go all through the California winter months into early spring. Then it was very intermittently audible as the weather warmed up. That repeated for the 2 summers I owned it.

Driving in 4h or 4a would usually make the sound disappear, but not always.
That's why I assumed it was the diff but I could not make any sense of why it happened sometimes in a 4x mode and/or why it was temp related. Didn't matter if I had driving it plenty to be all warm and happy, it would still occur.

Sounds like you are free and clear to keep the IWE in tact if you decide to reconnect it (or have it done). I don't think there is anything you have done or can do to make it any better.

Generally speaking it is suggested to enable 4x4 once in a while, monthly or every couple months, all sort of opinions. I was not very diligent about using 4x4 routinely, nor have I been for the past 29 years of 4x4 ownership.

 

To follow suite with you. The new valve didn’t work. Sound returned on second short drive. Going to try testing the rest of the system this weekend pending time availability. Without combing through threads, what was your solution Ingot? New truck?

 

No, didn't get a new truck because of it.
A car instead.

Kidding... Yes I did trade but not for that reason. I did the testing probably within the first 9 months (not sure I did that through the winter months and it did take a while to digest and understand fully how the system is designed to work. I had the truck almost 3 years, so lets say I drove it 2 years after testing and the problem (noise) never seemed to worsen.

After testing all the IWE stuff and checking wheel bearings for play (by attempting to wiggle the wheel) I stopped troubleshooting. I do not actually know if a wiggle test is a good way to check for wheel bearing play anymore with the bearing being part of an assembly vs having a locking not to set the preload.
My wheels spun freely and silently though. So either I had angry hubs that groaned from time to time or it was the diff. It didn't sound like anything related to the front driveshaft or t-case.
As a matter of fact, I did change the t-case oil just because of routine maintenance but it may be worth noting that it didn't accidentally correct any noises.

If nothing else, the noise is an annoyance and embarrassing.