2009 Lincoln MKX starts to "howl" at times. Very annoying. Has 45,000 miles. Little service history. Howling goes away when brakes are applied but often comes right back. We have deeply depressed the Emergency Brake pedal and then popped it back. That can also deaden the "howl." Seems to happen only on longer outings of 50 miles or more. Sometimes the harmonic howling can be overwhelming. Dealer thinks that we are crazy since it doesn't act up when we bring it in. Any suggestions would be awesome. Thanks. tdwyer@tjfans.com

This AWD has transfer case. Is it one of these "permanently sealed" jobs? otherwise would suspect this creature what distributes the drive forces~

Does it feel as though it is coming from the center or from one or more of the wheels?

I have never experienced this happening at night. It does continue with foot off of the acceleator. It does seem to be coming from the center versus one side or one wheel. I do not suspect the Steering. It definitely is related to the Brakes.

have you had your brakes serviced recently...what I'm getting at is that in machining the rotors/drums they probably inadvertently put a screw threads on there the pads or shoes to be forced to one side or the other creating a thup thup thup whenever the brakes are applied...if you haven't had brake service recently this couldn't be it...just a thought...have seen it before~

No. Brakes have never been touched.

Thank you all for your help. I will get the Brakes looked at.

I would check fan clutch or temperature sensor. Sounds like fan on constantly-gives that howling sound.