1997 Mercury Mountaineer

On your front DRIVERS SIDE AND PASSENGERS SIDE check your "Stabilizer Bar" "link" bolts .

IT COULD BE LOOSE, CRACKED, SPLIT OR MISSING ALL TOGETHER. WHICH IS CAUSING THE LOUD NOISE.
OR
IT COULD POSSIBLY BE A WHEEL BEARING OR A TIE ROD END.

I hope this helps you out.
Good Luck;
Rick

Here is a diagram to help locate the stabilizer bar.

The stabilizer bar "First Picture" #(1) is a long bar that runs across the front end suspension from near the drivers side tire just above the CV joint to near the passengers side tire just above the CV joint.

The stabilizer bar "link" (Second Picture) #1 is a long looking bolt attached to the top of the stabilizer bar by a spacer-bushing and large nut (Second Picture) #2.

The "link bolt" runs through the hole in the end of the stabilizer bar (indicated by an pointing arrow) "First Picture" secured by a spacer-bushing and large nut on top of the stabilizer bar (First Picture) #1.

Protruding downward from the stabilizer bar the "link" gets bolted with a spacer-bushing and large nut to the undercarriage. See"Third Picture"
BOTH TOP AND BOTTOM LINK BOLT "NUTS" REQUIRE 15 - 21 Lb/Ft torque.