Stumped by 4WD problem
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Stumped by 4WD problem
I've been having a problem with my 2016 Expedition. When I drive, it sounds like the 4WD is engaged. If you've ever driven at highway speed in 4HI, you know that you can sometimes hear sort of a hum coming from the front end at highway speed. If I go fast enough, I actually feel a little vibration.
I don't want this to get confused with the IWE hubs being partially engaged. I don't get any clicking, grinding, or rattling noises.
So I did a test:
I jacked up the truck, spun the front wheels with the engine off, and they were engaged with the axle shaft making it spin.
Then I started the truck, spun the wheels again, and they spun freely.
The system seems to be working normally, but I swear the axle shafts are turning when I drive it down the road.
So I did what might sound like a stupid test:
I wrapped some blue painters tape around the front axle shaft, and attached it to the swaybar link. If the shafts turn, I'll know it because it will break the tape. I also drew a line on the shaft with a permanent marker for a visual reference.
I then drove around the block getting up to about 25 MPH, pulled back in the driveway, checked the tape, and it was broke.
Thinking that the 4WD hubs were working, I then bypassed the vacuum solenoid so that the hubs were always getting vacuum. When I unplugged the hose, a lot of air escaped.
With the engine off, I jacked up the truck and spun the wheels again. They spun freely from the axle shaft because I still had the vacuum hosesstuck together. This tells me that the 4WD hubs are working, and that the lines are holding vacuum.
I then reconnected the solenoid, and checked the hubs again.
Engine off - hubs engage the shafts
Engine running - hubs disengage the shafts
Engine running and 4WD set to 4HI - hubs are engaged with the shafts.
WTH? Why are the shafts engaging with the hubs when I'm driving?
Looking at this from a different angle, is there a way that the transfer case can be engaging as I drive, and spinning the front axle shafts? It's in 2WD, but it has the 4A, 4H and 4L settings.
I don't want this to get confused with the IWE hubs being partially engaged. I don't get any clicking, grinding, or rattling noises.
So I did a test:
I jacked up the truck, spun the front wheels with the engine off, and they were engaged with the axle shaft making it spin.
Then I started the truck, spun the wheels again, and they spun freely.
The system seems to be working normally, but I swear the axle shafts are turning when I drive it down the road.
So I did what might sound like a stupid test:
I wrapped some blue painters tape around the front axle shaft, and attached it to the swaybar link. If the shafts turn, I'll know it because it will break the tape. I also drew a line on the shaft with a permanent marker for a visual reference.
[img]
I backed the truck down the driveway, pulled back up, checked the tape, and it was still intact.I then drove around the block getting up to about 25 MPH, pulled back in the driveway, checked the tape, and it was broke.
Thinking that the 4WD hubs were working, I then bypassed the vacuum solenoid so that the hubs were always getting vacuum. When I unplugged the hose, a lot of air escaped.
I then reconnected the solenoid, and checked the hubs again.
Engine off - hubs engage the shafts
Engine running - hubs disengage the shafts
Engine running and 4WD set to 4HI - hubs are engaged with the shafts.
WTH? Why are the shafts engaging with the hubs when I'm driving?
Looking at this from a different angle, is there a way that the transfer case can be engaging as I drive, and spinning the front axle shafts? It's in 2WD, but it has the 4A, 4H and 4L settings.