This means you have excessive pressure on one side of your power steering assembly. Your steering box may be worn out. Also, check your tie-rods for excessive play.
Worn steering parts. Can be many things. Have your steering components inspected.
loose nuts
Worn steering components
Could be worn ball joints, worn steering linkages, worn/out of adjustment steering box and or worn/out of adjustment wheel bearings.
You can tell that the rack in opinion steering is bad when there is excessive play in the steering will. You might also feel a shimmy in the steering wheel.
how do you fix play in a 1997 mercury mountainer steering wheel
You can raise the vehicle front or rear and move the wheel back and forth and up and down, so as to feel for play. Excessive play in the wheel indicates loose components, whether a wheel bearing or tie rod or ball joint. If there is excessive play moving the wheel left and right, then could be a tie rod. If there is excessive play up and down, then could be a ball joint. If there is excessive play all around, then could be the wheel bearing.
Not knowing the year or make of the vehicle in question, the answers I give are only generalizations. There may be excessive play in the steering gear box which requires a new gearbox to be installed. There may be need to replace the tie rod ends and relay/control arms. Check the pittman arm for excessive play. Check for loose wheel bearings, a complete inspection of the front end components would be advised.
A steering system of the parallelogram type is normally fitted with a steering box assembly. You should check for excessive movement in the steering box itself. This can be done by having the vehicle on the ground, and feeling the "free play" in the steering wheel with the road wheels in the straight ahead position. While watching the wheels to see how much you can move the steering wheel, before the road wheels start to move. Check this amount of movement and report any excessive movement to your supervisor.
If the steering wheel shimmy's at 55 -ish, then the front tires need balancing. Otherwise front end shake could mean something loose or worn in the front like a bad tie rod, ball joint, wheel bearing, strut/shock or cv shaft. You can jack the front end and check for play by grabbing the wheels with tires on shimmying the wheel left and right(tie rod). Up and down(ball joint) or excessive play could be the wheel bearing. Any excessive play indicates loose components.
If the steering wheel is loose while driving the steering rack may be going bad. A bad steering rack leads to a lot of play on the actual wheel.