I made another post a few days ago but have a bit more information. Wanting to see if anyone might have some ideas.

2017 with front end vibration and noise. Truck makes a louder low end humming noise and slight vibration in 2H, after switching to 4H the noise and vibration goes away "mostly". While in 4H I get the slight noise/vibration only when accelerating and deaccelerating, its the same noise/vibration but only at the start of accelerating and deaccelerating. I go back into 2H and its a constant noise/vibration.

So far I have had a local shop replace front drivers side wheel bearing and replaced both front IWE actuators. I have replaced the IWE check valve and tried a new solenoid for a few miles. I have also hooked up a vacuum pump to the line after the solenoid that runs to both actuators, it holds -25 steady. Is there something I am missing to test? Could this perhaps be a front diff issue? The truck does have a leveling kit, I do not know the height as I bought the truck from a dealer. The mechanic that has worked on the truck says he feels the noise is from the front end, not a transferase noise. He said he doesn't know what it could be after replacing the front IWE actuators. I'm taking it to another shop tomorrow in hopes of something new, they mentioned they can smoke test vacuum systems. But I have tested the vacuum already. Is there a specific way to install the IWE's to mate to the CV's correctly?

I have also pulled off the vacuum line from the solenoid to the IWE's while the truck was running and it is pulling vacuum threw the solenoid, however it doesn't feel to strong, I figured it would need more vacuum then what's pulling threw that solenoid to pull the IWE's out.

I'm starting to wounder if it might be a front diff issue? If it was the front diff giving me the issue, wouldn't it make the same noise in 2H and 4H constant, or am I miss understand how the front diff functions?

 

I had a second shop check into the issue. They believe its the front differential. I was told that its most likely the front diff bearing races spinning.

I guess my next question to anyone that might know, are all the 2017 or (2015-2020) 3.5l eb 4x4 front differentials the same? I have the Lariat,fx4,tech packages. It has 2h, 4a, 4h with rear locking. I am wondering if I found a low mile 2015-2020 wrecked f15 4x4 at such a place as pick-a-part, would it be as simple a pulling the front diff and just replacing the whole unit. Not sure if the Lariat/fx4 package with 4a is different then say an base model? Any input would welcome.

 

I chased a grind, noise, something something for two years.

Changed the brakes, pads, IWE's and Hubs. (DIY).

Finally took it to ford. Ended up being the Front Diff.

At first I occasionally heard it in 2H, then in 4a/H, but eventually it was constant even in 2H. For Lariats and Above the Diff may not be engaged in 2H but it still spins.

 

I have taken the truck to two different shops, and they are both leaning towards the front diff. I just dropped off the truck at the local transmission shop as ford is booked out. However the ford dealership doesn't have a time line on getting the new front diff. I was recommended a wrecking yard... which could work. Does anyone know if there is a difference between the trims. I noticed you said Lariats and above front diff still spins even in 2H. Are the actual front Diff in the Lariat and above different then the lower trim models? Thanks for any advise guys!

 

I believe it's the transfer case. Lariat and above the diff continues to turn even in 2h but not in below lariat.

Someone else can better explain it !

 

I have also heard this. Seems to make sense, the TC would be different but same front diff's

Hopefully someone can chime in if the actually front diff as a whole are the same "as in internal part numbers and housing part number" if so I can then source a front diff pulled off a wrecked 2017 f150 regardless of the trim as long as its the same gearing. Would be even better to know if all the model f150's from 2015 to 2018 are the same front diff assembly.

Not to mention, if it is the case that they are all the same front diff besides gearing, it would make since to try and source an actually lower trim model in hopes it might have less wear and tear because its not always spinning "not that always spinning is bad, but its bad if there has ever been a stuck or malfunctioning IWE" I would rather source a lower trim front diff in the case they are the same.

 

Good idea trying to find one from an XL or XLT since it has not been spinning in 2H due to the shift on the fly transfer case.

Car-part.com seems to be showing 2018 and 2019 parts for fitment on a 2018. I would grab a 18/19 in the correct ratio. Looks like they range from $375-500. Not bad! For example near me I see one from an XL with 5k miles for $475, that's a no brainer.

I don't have enough experience to say whether a 2015-2017 would fit. Car-part has good photos if you want to try comparing.

To check the IWE for certain, drive the truck for 1 mile and then leave the engine running, jack up the front and spin the tire.
The engine will not disconnect the IWEs until >0.5 mile traveled after engine start to let adquate vacuum build up.
A good sign they hold steady vacuum at the IWE and through the lines.

 

Thank you for the help! I have not used that part locater before, very quickly was able to pull up multiple trucks near me!

 

Sorry, meant to say 18/19. Ok glad that helped you find one!

 

I was very surprised to find a handful of grade A's and a few grade B's locally! I delivered to the shop yesterday, they will flush/add new fluid and reseal it. Hopefully all goes well.