IWE Vacuum Line Missing? Capped at supply and check valve?

[Nitsuj]

Hello All,

2017 Ford Expedition EL VIN Build date 12/16/16. One owner.

I have read the forums, which have been very helpful. I am wondering if I am missing the vacuum line that contains the check valve (part number AL3Z-3A788-A)? I have the check valve, but it is capped on the bottom and capped on what would appear to be the supply side. See the circled in blue areas in the attached photo "My Expy Missing Line". I am also attaching a photo, "All Others", that show the line circled in yellow as it seems to be on almost all other F150s and Expeditions that I see on the web. This would seem to be the line that I am missing. Or, am I?

I did find this post in the forums: https://www.expeditionforum.com/thr...point-me-in-the-right-direction-please.55954/. This is not my generation, but it is almost the same issue. It does not provide an answer, though. It references some video, which I can not find.

TSB 20-2013 even shows the part attached to the vacuum reservoir. I can't find a more recent TSB (but may have missed it) where it suggests to remove the line completely.

Background: IWE issues, typical grinding. I asked the dealer to diagnose and quote. Dealer stated I should replace IWE actuators and hub assemblies and that they could not find any other leak. They said they completely checked the system. Believing them, I replaced IWE and hubs. Grinding still exists. I should have run my own diagnostics before replacing. Old IWEs hold pressure, no leak in vacuum lines. New IWEs pass test. No pressure at bottom of solenoid. No release of pressure when removing hose to capped check valve that is attached to vacuum reservoir. It seems like I am missing the supply hose. It looks like it was there - lack of dust on vacuum reservoir where it would attach - but why the caps? Is this what is causing the problem. I have a new solenoid and check valve (without hose) coming tomorrow. But, what supplies the vacuum if this hose is missing?

Any help?

 

[Nitsuj]

I might have an answer for my own question. See https://www.blueovaltrucks.com/tech...d-to-know-about-the-iwe-system-and-then-some/

It states: If you suspect that your system is malfunctioning and you are not able to test it right away or want to drive and not damage anything, disconnect the line coming off the intake at the check valve and plug both ends of the line. This will not allow any vacuum to reach the system and leave your hubs locked in all the time. This is fine and wont cause any damage as long as the hubs lock correctly.
I think the dealer removed the line and capped the system. They completed work on the differential for me during the visit, but I told them I would handle the IWE by myself or at another time due to $$$, and took the car.

At the visit, we had an extensive conversation about drivability with bad IWEs and they told me to drive in 4WD auto. When I questioned them about their diagnostics and no mention of needing to replace the check valve, solenoid and lines, they said it was only IWE and hubs. They provided a "job lines with parts" report that only listed actuators and hub assemblies. They mentioned nothing about replacing the missing line. Nothing about removing the line and capping the system, either.

Since my old IWEs pass a pressure test and the hub assemblies seem ok, even with 114k miles and the timing of when the grinding began right after a previous visit for an oil change, I am starting to wonder if the line was removed and system capped at an earlier date.

I am going to test everything again according to the TSB and then I am going to make some inquiries at the dealer. At least I didn't pay them $5,500 to do the job and I am in for only the cost of parts - and the unforgettable wrench time with my son doing the labor.

I might have some used hub assemblies and IWEs looking for a home, if someone is interested.

 

[Nitsuj]

I do have more answers! See https://www.expeditionforum.com/thr...ise-from-front-wheel-area-july-23-2024.56448/

So, yes the dealer capped the lines according to the TSB listed in the post above. They did not tell me this. And, even after the IWEs and hubs were replaced, with the capped system, I still had the grinding, clicking, ratcheting noise at front wheels when turning at slow speeds - sort of like a truck turning with 4WD engaged (wonder why /sarc).

Since I had a new solenoid and new check valve/line (AL3Z-3A788-A is the Ford part #, I used Doorman 926-391) I uncapped the system as others have mentioned in the above link. I installed the new line. I will see which method makes less noise. Sort of seems, though, that the less the IWEs are engaged (2WD) the less wear and tear on them and the hubs.

If anyone has tried the line replacement solution, please let me know. Or, if they think I should drive the system capped, please let me know.

 

[Alliance]

After installing the selenoid, check valve, and lines did that solve your problem?

 

[Nitsuj]

It has not.
I drove it with the line/tube replaced for a day. I still had grinding when turning at a slow speed. Just like when driving in 4wd and turning sharply.
I have been driving with the line removed. Same situation.
Interestingly, in both situations, the grinding is more pronounced when first starting to drive. After some driving it seems to dissipate. But I need to confirm this.