Hey Ford Techs....2016 Expedition issue

[Jim Oaks]

my 2016 Ford Expedition XLT 4x4 just turned 70,000 miles on my way back from visiting family in Ohio. I noticed that there is a hum in the front end. There's a little vibration that makes me think of a bad bearing, or the front 4x4 hub is engaged.

Even though the truck has 70,000 miles, I'm kind of surprised that it could have a bad wheel hub. I'm wondering if the front 4x4 hub still uses vacuum to keep it disconnected. On my trip, I hit a large chunk of rubber with the right front. I'm wondering if I could have damaged something that's causing the 4x4 hub to engage.

I haven't jacked the front end up yet to try and figure out what the problem could be. I started wondering if the 4x4 hub could be engaged, and figured I'd try to get some input before I jack it up and start looking around.

 

[alwaysFlOoReD]

Does the hum change or disappear when turning? That would suggest the hub to me.

 

[85_Ranger4x4]

Dads 05 150 would buzz when the 4WD hubs were dragging. Sounds terrible.

 

[adsm08]

To my knowledge they are still using the IWE vacuum hub setup. Looking at pictures of the CV shafts supports this idea.

First two things to do are check and see if it changes as the wheel turns, like Floored said. If it comes and goes with slight turns of the wheel you have a bearing.

The next is to open up the hood, and back on the firewall is a vacuum control solenoid on the passenger side. Unplug it. That will lock the hubs in totally and if one is dragging it will eliminate the noise it makes.

They drag because one side looses the vacuum seal somewhere, usually a hose splits, or a seal inside the unit fails, and that side locks. The other side only gets partial vacuum and so it kinda jumps in and out, making it drag and rattle.

If that makes the noise go away look for disconnected or broken vacuum lines to the hub unit.

One other thing that is often overlooked by those who are inexperienced with these setups is that your wheel bearing has a pilot bearing in it for the CV shaft. THAT bearing can fail and cause a huge range of noises from a barely audible squeak to a growl just as if the main bearing was bad. I have taken over a lot of NVH jobs from junior techs who were stumped because they thought it was a wheel bearing, but couldn't find any signs of one being bad, but weren't checking that pilot and it was the problem.

 

[bobbywalter]

seen boot clamps squeek. figured it out after it broke... on a blazer.


are you sure its not a tire? when was the last rotation? before you left?

 

[Jim Oaks]

Tires were rotated at the last oil change around 5,000 miles. It's due.

 

[Jim Oaks]

I need to get back in to this before I give Ford their Ranger back.

I thought it sounded like the noise was coming from the left front. I had my daughter ride with me, and then we switched so I could ride in the passenger seat. We both thought it sounded like the left front.

I changed out the bearing assembly, only to drive it and still hear the noise.

What's weird to me is that if I jack the truck up and turn the front wheels, they're locked with the axle. But if I start the engine, the wheels turn freely. I don't hear any clicking / grinding sounds like it's trying to engage. But I get a sound like I have a worn out axle shaft, and if the hubs are working, the axle shouldn't even be turning if it's in 2WD.

I'm going to pull the vacuum lines and do the test where you check for vacuum, but it seems to me that I do since they disengage when the truck is running.

Any suggestions??

 

[adsm08]

The IWEs have to be disengaging properly. It's a single split system, so a leak in one side causes both to engage.

I take it rotating the tires didn't change anything.

 

[Jim Oaks]

No. I put on new all-terrains, so there's a little noise from them. I need to drive this thing. I haven't really driven it in a few months.

It it possible that it could loose vacuum when it's actually rolling down the highway?

 

[adsm08]

No. I put on new all-terrains, so there's a little noise from them. I need to drive this thing. I haven't really driven it in a few months.

It it possible that it could loose vacuum when it's actually rolling down the highway?

Oh yeah. Most of the time when the loose vacuum it is under load.

If you suspect the IWEs are loosing vacuum unplug the control solenoid on the firewall and see if that makes the noise stop.

 

[Jim Oaks]

If I unplug the vacuum line, won't it lock the hubs in?

What are the normal causes for it leaking under load? Is it typically the line or solenoid, or could it be in the hub actuator?

 

[adsm08]

If I unplug the vacuum line, won't it lock the hubs in?

What are the normal causes for it leaking under load? Is it typically the line or solenoid, or could it be in the hub actuator?

Unplug the electrical connector at the switch, not the vacuum line itself, that will cause a leak. It will lock the hubs, but the rattle is from only partial vacuum causing them to be only partially engaged/disengaged, so cutting it off altogether will get it out of that in-between state.

IME the most common cause of vacuum loss is failed seals in the hub itself, but yours is pretty low mileage for that. I'd say line damaged is more likely.


You can also use a hand pump to see if the hub system hold vacuum.

 

[Jim Oaks]

I don't get a rattle. I get a hum at highway speed that sounds like the truck is in 4WD. I don't hear any of the noises associated with the hubs trying to engage (clicking, rattle, etc)

 

[adsm08]

I dunno. The problem now is the same as when you first posted this, it is very hard to do noises if I can't hear them.

 

[Snoranger]

We've had a few issues with the IWEs on the Sheriffs Expeditions and Raptor. Almost ever time it's been due to a vacuum line issue. They are either disconnected from them doing something stupid, cracked up at the end by the top of the strut tower (most common issue), or a bad wheel bearing.