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Ok, got a question. My '20 F-150 XLT 4x4 just started making a howling noise when in 2wd, sounds like the front end. It goes away when I switch into 4wd high though. Aren't the front hubs supposed to free wheel in 2wd? I jacked front up and axles and driveshaft turn when I rotate wheels. Any ideas? I'll check with dealer when they can check it.

 

My 18 f150 started what may be the same thing last winter. Mine does it any time it rolling , 2wd or 4wd. I put it on stands with all four off the ground and it's quiet in 2wd but I hear it 4wd. My dealer said tires but it makes the noise with the tires off the ground! I have an appointment with another dealer so hopefully I'll get a better answer. Howl is probably the best way to describe it.

 

Your IWEs are probably trying to engage due to a vacuum leak from a failed line, solenoid or check valve.

 

The dealer that looked at it said they didn't find any problem with engage and disengage. They kept saying tire noise even after I told them it made the noise with the tires off the ground. I'll see what the other dealer tells me this week.

 

I dropped mine at the dealer yesterday, waiting for word.

 

I've had the same problem. First time the system acted up they found the problem, second time they couldn't duplicate it since it made the noise intermittently. The IWE solenoid on the firewall is cheap so I just bought one out of my own pocket and replaced it and the noise hasn't come back in over 2000 miles.

Maybe take them out with you and show them the noise and how it stops when your go in 4wd.
Another thing you can do to help them see that the noise isn't the tires is unplug the wiring from the solenoid which deactivates the system and locks the front end in and then go for a long drive that way, if you have the transfer case with the auto position that keeps to IWEs locked in full time also.

 

Usually they are "free wheeeling". With engine off, no, IWEs locked due to no vacuum, and solenoid has vented off vacuum.
Upon engine start, truck has to be driven about 1/2 mile before solenoid is energized allowing vacuum to IWEs, this happens at EVERY key cycle. Ford says it's a warmup cycle for front diff.
Howl, not a grind or ratcheting sound? Wheel bearing? Have you had a level done ?

 

Need info on your truck, year and trim level would be good to know before I try to help you out.

 

Yes, howl only, not wheel bearings. No level done. It's at dealer now and they're trying to diagnose. Thanks for the explanation. I did notice at start of each drive cycle it was quiet until about a 1/2 mile then howl starts.

 

2018 STX 4WD extended cab 5.0 . Mine makes the noise all the time . When I had all 4 wheels off the ground on stands, it only makes the noise in 4WD

 

I mentioned wheel bearing, because at the end of the warmup period, the IWEs release, and loading on the wheel bearing could change. It's evidently a rotational issue, and the only thing that should be turning is the spindle/wheel bearing. Please let us know what the dealer says, it'll help to educate all.

 

I needed to know if you had the TOD TC. You don't, but that particular TC turns the front diff all the time, regardless if 2H, or 4H, due to the clutch in the TC. For lack of a better term, it "leaks" some power forward. There has been problems with some front diffs.

So, in 2H, on stands, no noise. On stands in 4H it does. When on the ground, in 2H, do you get the howl?

 

Ok, will do, (truck only has 12,500 miles and bearings felt fine when wheels rotated). From your description of operation sounds like one of the hubs isn't engaging since it starts after approx. 1/2 mile from cold start. But will see what dealer finds & repost. Thanks for the help.

 

A ;lot of good discussion here. I hope the original poster gets answers on his truck. I just got home with mine and it's quiet once again. They found the left front wheel bearing bad. That's what I told the first dealer that told me tires.

 

I had a call from the dealer and Ford got back to them with some more tests to run which they're doing. I'll post with what I find out.