I still think you are losing vacuum and the IWE is partially engaging. Does the grinding dissappear in 4WD?

 

that’s correct, it goes away in 4wd. Could it be that there is a leak in the hose going from the IWE up to the valve? Right side is smooth as butter, just the left.

 

There's more than one possibility of not having sufficient vacuum to keep that (or both) IWE from trying to engage. The most common is that check valve. But yea, I'm sure with that convoluted vacuum line loop Ford has that there's multiple places that it could leak.

The worst thing about what you describe is that you have new IWE's and they will be damaged again in short order if the grinding is still there. I'd drive in 4A until you can find the cause for weak vacuum.

Or you could simply remove vacuum altogether and just allow the IWE's to stay engaged. It doesn't harm anything other than a little hit on fuel economy because you are turning the front axles even in 2WD. It's actually less of a fuel hit than 4A when you think about it.

 

That’s right, I am worried about damaging these IWEs, since they’re..a day old haha. I will drive in 4A for the weekend and hopefully they’re able to find the leak on Monday. Will being in 4A damage anything, especially at highway speeds?

Would it be bearings if the noise develops while in 2WD?

 

You can drive in 4A 100% of the time whether the road is dry or wet or whatever without harm to anything.

 

Does the 4A have the same affect on the IWEs as 4H?

 

What year and how many miles?

It could be bad iwe, I had a few bad ones plus one broken one when I did mine. Also bad CV axle could be the culprit. It's strange they would keep replacing stuff that is easily tested.

 

What year and how many miles?

It could be bad iwe, I had a few bad ones plus one broken one when I did mine. Also bad CV axle could be the culprit. It's strange they would keep replacing stuff that is easily tested.

2019 with 53000 kms. They found metal flakes etc in the front diff (rebuilt), inspected and replaced the IWEs as they had gone “bad” but wheel bearings were good. Foreman did say the check valve and solenoid were good to go and good vacuum. That’s why I’m stumped. Could the valves go that quickly? At this rate, I’ll have to buy in bulk haha.

 

The check valves are pretty simple, not sure how often they go bad.

I'm wondering if there is a leak in the line? But a specific rpm under a specific speed seems too perfect. Bad CV axle? Any way you could take a video of it?

 

The check valves are pretty simple, not sure how often they go bad.

I'm wondering if there is a leak in the line? But a specific rpm under a specific speed seems too perfect. Bad CV axle? Any way you could take a video of it?

Absolutely, I’ll make one in the morning. It isn’t as loud as it was before the front diff rebuild and IWEs put in. But mostly notice is when turning left. Turning right is smooth as butter.

 

No reason to be sorry!
And although dealerships deserve that quip, it's NOT normal, but is all too common.

That check valve is a $6 piece of cheap plastic. You could have a poorly functioning new one. A fella here recently took his off and could blow through it both ways, which is not supposed to be possible. But by blowing through it the wrong way it clicked into place and became one-way again.

You can also install 2 of them back to back for redundancy. Less likely for 2 of them to fail simultaneously. They are easy to reach and verify that they are working properly.

 

No reason to be sorry!
And although dealerships deserve that quip, it's NOT normal, but is all too common.

That check valve is a $6 piece of cheap plastic. You could have a poorly functioning new one. A fella here recently took his off and could blow through it both ways, which is not supposed to be possible. But by blowing through it the wrong way it clicked into place and became one-way again.

You can also install 2 of them back to back for redundancy. Less likely for 2 of them to fail simultaneously. They are easy to reach and verify that they are working properly.

Could there also be a leak in the actual line from actuator up to the valve? I’m going to buy a valve to keep on hand but also inspect the lines. I’m sure it is somewhat exposed, so prone to the elements. I’m in wonderful Canadia..figure the seasonly road offerings might have knicked something? Or the tech just didn’t connect it properly?

 

Of course there could be. There could be a leak in the vacuum reservoir. The whole IWE vacuum harness is a single assembly that Ford sells. Depending on the age of the truck, you might just replace the whole thing if you can't isolate it.

 

It’s a 2019 but at this point, I’ll suggest that to the dealer. I had to get Ford Canada Corporate involved and switch dealers. Dealt with this since February 2021 haha

 

Ouch.
Honestly, if it were me and I had Lariat-up, I'd yank the vacuum and avoid the whole dealership frustration. I've vowed to if mine gave me intermittent trouble.

 

Ouch.
Honestly, if it were me and I had Lariat-up, I'd yank the vacuum and avoid the whole dealership frustration. I've vowed to if mine gave me intermittent trouble.

Will it have an impact on ride quality (..sorry for the ignorance once again)?

 

The only thing you are doing by removing the vacuum is you are engaging the IWE. The IWE is just a vacuum operated hub lock. So you are permanently locking the wheel to the axle. (regardless of whether the axle is connected to the transmission via the transfer case)

AWD vehicles have their hubs connected to their drive axles permanently. And on your truck if you drove it in 4A your IWE's stay engaged full time even though the truck is not always sending torque to the front wheels. (4A is like part-time AWD. You paid for the luxury on that Lariat. Have some fun enjoying an F150 that has modern sophisticated traction management. That's what it's for!)

Again, you will probably notice a small drop in fuel efficiency because you slightly increased your 2WD rolling resistance.

 

The only thing you are doing by removing the vacuum is you are engaging the IWE. The IWE is just a vacuum operated hub lock. So you are permanently locking the wheel to the axle. (regardless of whether the axle is connected to the transmission via the transfer case)

AWD vehicles have their hubs connected to their drive axles permanently. And on your truck if you drove it in 4A your IWE's stay engaged full time even though the truck is not always sending torque to the front wheels. (4A is like part-time AWD. You paid for the luxury on that Lariat. Have some fun enjoying an F150 that has modern sophisticated traction management. That's what it's for!)

Again, you will probably notice a small drop in fuel efficiency because you slightly increased your 2WD rolling resistance.

So I’ve been running it in 4A. Noticed the grinding turning left subside a little bit but it’s still there. In 2WD it’s very apparent but turning right is smooth as butter. I guess I’ll just be only making rights..

Going straight at highway speeds, I can feel the rotational grinding in the gas but braking is smooth.

 

A tuned 2018 3.5EB with somewhere around 425-440RWHP. For many many thousands of miles.

But I'm not a boost-launcher. In fact I'm not really even a 0-60 guy. I'm more a 15-80mph guy. Try to be smooth when rolling into WOT.

The Powerboost has just short of 600ftlbs of torque and Ford puts the truck into 4A when you intend to feed it coal. There's nothing Ford says that even resembles that they caution using 4A. I'm not exactly sure why folks feel queasy about it.

 

Unsure what the system is capable of and don’t want to blow anything up. I’m not intentionally hard on my vehicles but they definitely don’t see any easy day some days. I’ve seen things that can handle the abuse and some that can’t wasn’t going to push until I know for sure what it’s capable of.

 

The t case is pretty stout and I think even the newer ones use 8.8 fronts, which is also a pretty proven axle.

 

As a side note, I've discovered my driver's side CV axle is spinning with the wheel in 2wd. So, I get to figure out if I've got a leaky vacuum hose or another bad (less than 2k) iwe. This iwe was installed by a reputable shop when they dislodged the bad CV axle.

 

I believe if the transfer case was a weak spot we would have plenty of threads regarding it. Afterall there are plenty of folks tuned and boost launching in 4Hi on prepared surfaces and sticky tires.

So 4A, with its clutch forgiveness, along with just normal driving on street should be well below the max engineered threshold. And it IS absolutely intended for street use.

 

Right hub seems like it’s not unlocking fully…. That’s my guess.

 

Disconnect the vacuum before you make it alot worse.