My 2000 Lincoln Towncar started making a very loud vibrating noise that sounds like a car riding over the highway shoulder on a rumble strip. it doesn't do it all the time, but it's doing it with a greater frequency from when I first started hearing it years ago. I've had the car now for over 4yrs.

SOURCE: REPLACE HEADLIGHT ASSEMBLY IN 2000 LINCOLN TOWNCAR

Open the hood and make sure the car and the lights are off.
Remove the plastic protective cover.There are 3 knobs,turn halfway and pull.Put aside and out of the way.
Remove the three pins that are holding the light assembly in place.These are flat rods with a little bend at the end.
Twist and un-plug the lights,now you can remove the whole lens.
The light bulbs can also be removed and replaced from this point.
Make sure all the bulbs are working before you put it back together.

SOURCE: 99 Lincoln Navigator

There are a couple of parts you can try and if they have not coded on the cars computer, a dealer may be able to look at service bulletins. There is a differential speed sensor and an antilock brake sensor. You can have locking clutch paks and may require a special additive. An old fashion U-joint can vibrate under load.

The good news is with a Vin# the dealer can pull up the entire service history if the car was serviced under warranty or in a Ford dealer anywhere. They just do not want you to know the past owner.

SOURCE: clicking noise under dash

It likely has a bad temp control actuator for the blend door.

SOURCE: 96 lincoln town car- loud humming noise

I had experienced the same problem with my 93 TC. I'll try to make it short. Replace the Idle Control Valve. Cost me $50 at AutoZone. It has a electronic plunger that has a rubber o ring on the end of it. It separates two air chambers inside the valve. When the rubber gets old and the plunger is suppose to cut off the air coming in from one chamber to the other, the air gets sucked between the chambers across the old rubber causing the humming noise. That is also why the engines revs up and down and wont idle right. It is located between the firewall and the back of the motor just to the left (drivers side) of the throttle control assembly. When you look up on the internet on how to replace it, it will tell you to remove all the housing surrounding the wiper blade control arms and assembly so that you can access it. If you take your time, just remove some of the hoses and wires connected around it and you can access it without removing all that ****. Only has two screws to it that point up and can be reached with a ratchet and extension. Car runs great now and finally got rid of that noise.

SOURCE: I am feeling a rumbling,

Probably just a rear wheel bearing

Testimonial: "Thanks. I changed my tires recently from Michelins to Vogues and that's when the trouble began. I thought the new tires were not balanced properly. "