Aaron407
Member
I noticed on the weekend that our 2015 Navigator (same engine/drivetrain as an Expedition but a heftier price tag) had a subtle but more noticeable humming noise specifically from the front driver side wheel area when driving at highway speeds in 4A. The sound goes away completely after switching to 2WD, sounds almost like light engine braking, and is not really noticeable under about 55 MPH. I've noticed other people mentioning noise related to IWE still partially locked when switching to 2A, but I haven't found info on noise only when in 4A. Would it be worth changing out the 4WD solenoid and check valve to rule them out since they're reasonably cheap? Any ideas of what else it could be? It sounds like it's coming specifically from the one corner, so I'm leaning away from transfer case issues, but I'm not sure.