2015 f150 4x4 3.5 EcoBoost, lariat. 6inch lift

Truck has a humming noise at any speed and just always constant. Doesn't change if I turn left or right. If I put it in 4a, 4l or 4h the noise isn't constant anymore. The humming only happens for a second when I hit the gas or take my foot off the gas.

Replaced IWE on the firewall. And the solenoid below it. No change.

Got the truck up off the ground and started listening. I can't get the humming noise to happen in 2wd or 4wd off the ground. I did notice a sort of clunk or click when just touching the gas. Sounds as if there is play in the front diff or transfer case. So thought maybe it could be the front drive shaft as the boot closest to the transfer case is all torn apart. So I took it off, and where the front drive shaft connects to the front diff. It has play and has a sort of click noise. It goes about a 1/4 turn then clicks and starts spinning the front tires. Before I went ahead and replaced the front driveshaft, I removed it and drove it around. Driving around with out the front driveshaft was no noise in 2wd or 4wd. So i thought that had to be it and replaced it. Damn it, still no change now.


Any tests I can do to figure out the problem or rule things out. I am stuck and don't want to spend a ton of money.

P.s before doing anything I have done. Brought to a shop, and they wanted to replace both hub assemblies for 2400 bucks. That's why I am doing the work myself. And pretty sure it wasn't the hubs..

Can't seem to upload my video. Here is a link on YouTube to the play in the front diff. Normal or?
https://youtu.be/QKincCT1ZQw

 

Need some clarification. There is no IWE on the firewall. They are the at the wheels and is the actual part that locks the wheels to the half shafts. Did you mean that you replace the solenoid and the check valve?

Have you done a visual inspection of all the lines? Pay close attention to where the rubber lines from the IWEs (on each side) connect to the plastic lines up on the frame. If you have a way to check vacuum, I'd do that also.

However, it does sound like you may have a bad IWE or possibly both if you already replaced the solenoid and check valve and find no leaks in the vacuum lines.

One other possibility could be the front diff. I'd suspect the IWEs first.

 

That seems like a lot of slop IMO. You'll always have a little, but that's beyond little.
$2400 to replace the hubs? Sounds high.
BTW, the IWEs are on the end of the halfshafts going into the hubs, not on the firewall. The only things on the firewall is the vacuum reservoir and solenoid.

 

Beat ya to it John.

 

Sorry I meant the check valve. New to learning fords and what not .

I did disengage the line on the check valve just now and the sound goes away driving. Not sure if that helps more with diagnosis..

 

With the lines disconnected, the front IWEs are engaged. That means the half shafts, front diff and possibly the shaft to the TC are spinning.

Do a visual inspection like I suggested. If you don't see any thing then do this with all lines connected again.

1. Drivers side, pull the rubber line off of the IWE.
2. Plug both the hose and the connector it connects to on the IWE.
3. Go for a spin.
4. Do you still get the noise? Yes, then the passenger side is probably bad or you didn't seal the lines tight enough.
5. Reconnect that IWE to the hose.

Now, repeat for the passenger side. If you get a noise there, then the drivers side could be bad.

If you get noise both times, I'd recheck the lines more carefully because that could mean both IWEs are bad.

 

So I disconnected each line individually and drove to see if there was noise. No noise for both sides, except every so often you would hear it for a second. It happened for each side. No problems or anything I can see under there. I did forget to mention that about 2000 kms ago they did the front pinion seal.

 

Is that about the time the noise started?

 

I can't remember if the noise started right away after. But it definitely did come after.

 

It might not hurt to go back to the place you had that work done and ask them about it. Maybe take a look around where they did the work to see if you can see anything. Probably not but, worth a shot. Also, it might not also hurt to check the fluid level of the front diff. I believe, with the truck on level ground, if you take the top (not the bottom) plug out, the fluid level should be even with the bottom of the plug.