There is a noise in the rear suspension on my 1994 Mercury Villager that the dealer has been unable to trace for over four years now. The noise occurs when backing out of a driveway, going over a bump or a curb, and sometimes even when braking. The noise sounds like an old spring return for a door. It creaks and groans.
They have replaced the rear shocks three times and the brake shoes and drums three times. Each time they replace the shocks the noise goes away for a day or two and then gradually returns.
I can produce the noise to some degree by moving the rear suspension a certain way. Then using my stethoscope, I tracked it down to the rear of the leaf spring. So, what gives? Where is the noise coming from? I'm about to solve the problem by driving it off a cliff (tough to find in Florida).
You and your stethoscope were definitely in the right area. We found an updated Mercury technical service bulletin referring to a "crunching/grunting" noise in the rear suspension of 1993-'96 Villagers, which seems to coincide with your "creaking/groaning" phenomena.
The bulletin number is 97-1-11, and will give the part numbers needed to replace both leaf spring rear shackle and bushing assemblies. It seems that a defect in the factory units allows the bushings to float in the shackle assembly as opposed to stretching back and fourth with the movement of the rear suspension. This slippage is the cause of the noise. The temporary disappearance of the noise after the shock replacement was probably just an aftereffect from putting the vehicle up on the lift where the suspension was stretched to one extreme.