Recently purchased a 2015 4x4 Lariat with 3.5L Ecoboost with 97.5k miles after totalling my 2017 XLT 4x4 by hitting a deer. I never had any issues with my first but have run into a couple with my current.

I had a metal scrapping sound at highway speed that thanks to everyone I was able to eliminate that noise by switching out the check valve. Now after crossing the 99k mile marker I’ve heard a humming type of noise sporadically when below 20 mph. Sometimes it’s straight line sometimes turning when I get the hum. I will try to attach video here.

This past weekend I went through vacuum test on IWE actuators, lines and reservoir and all check out well. My question is, with it being so sporadic could that affect the IWE test results? Should I switch out the solenoid or is it something else?

 

I would once again check for iwe issue. Simply unplug the solenoid for a few days, see if sound goes away by leaving them engaged. Then you can decide if you need to chase iwe or possible wheel bearing.

 

This seems to be a mystery issue for several of us. I've been chasing mine for a year at least. Did the easy IWE stuff (vac check, solenoid, check valve) to no avail. Turning left seems to silence it, but both front wheel bearings feel great...no noise or play and silky smooth rotation when off the ground. Mine happens primarily when off throttle, at very low speeds as you've noted, and I can feel it in the steering wheel and pedals. Putting it in 4A does NOT eliminate the noise, but does seem to change it from off-load to under load. Wish I had more help for you...