Common symptoms necessitating replacing the steering rack are cold morning stiffness or lack of assist, noise, or leakage from the rack. It is no longer economical to rebuild the racks with the price of factory rebuilt racks. Old racks tens to wear their housing, rendering them useless except to a professional rebuilder who can sleeve the housing. New rebuilt racks contain this hardened sleeve and last much longer than the original racks. Maval, the brand we use, offers a lifetime warranty.
To replace the rack, first remove the cover and floor duct under the left dash. Total removal is not required, just undo the left most screw and fold them down so you can access the 13 mm pinch bolt on the steering column shaft where the universal joint (knuckle) comes in. Loosen and remove the lowest bolt here.
Raise the car and remove the front tires. Break loose the 22 mm lock nuts holding the tie rods adjustment, then remove the 19 mm nuts holding the tie rod ends to the spindles. If the tie rod end turns and the nuts won't come off, you can apply downward pressure on the tie rod end to hold it to get the nut off. Air tools are nice, zip, zip. Once you get the nuts off, turn the spindle so the tie rod end extends outward ( turn wheel to right to remove left tie rod end etc.). Hit the SPINDLE at the place for the tie rod end with a hammer and the tie rod will pop out. Be careful not to hit and damage the threads on the tie rod end. Leaving the nut on the end of the rod will help protect the threads until you pop it loose from the spindle. Using a splitting fork usually damages the tie rods boot allowing dirt in and grease out. A screw press works well if you have one, but the hammer is the easiest and cheapest way to remove them.
Reach in through the hole that the tie rod comes through on the left side of the car with a 13 mm and a long extension. A swivel makes things easier. Turn the steering shaft so that you can access the 13 mm bolt/nut in the column knuckle through the hole. Put a wrench on the nut and the socket on the bolt and remove them. Slide the knuckle upwards off the rack. WD-40 makes it move easier, a flat screwdriver may be needed to spread it open. Inspect the jopint for stiffness. Make sure it is free in both directions and has no play. If the joint is stiff, look here. If it has play, replace it.
For the lines, I bought a Craftsman 16/18 flare nut wrench and cut it exactly in half. The fittings on the lines are 16/18. Put the wrench on the line and use something to pry on the wrench to loosen the lines.
Have a container nearby to catch the old fluid as it flows out. There is usually a worm clamp going around the whole rack securing one of the lines to the rack and several tie wraps also. Remove the clamp by completely unscrewing it and cut the tie wraps. Don't forget to replace these as they are necessary to keep the lines out of harms way of the exhaust and belts.
Remove the 2 19 mm bolts and nuts holding the rack to the frame. I put a wrench on the nut from the tie rod end holes in the body and use a socket on the bottom bolt. Once you have the rack free, slide it slightly to the right and line up the shaft the steering column attaches to with the inner driver boot at a point where the boot is smaller. You may find it necessary to remove the speedo cable from the tranny to get clearance. It just unscrews and slides out. If you remove it, watch for its seal falling out (it usually stays put). When you put it back, make sure the inside square cable inserts into the drive gear.
Now turn the rack so the shaft points down, being careful not to tear the inner driver boot. Play with it until you get it past, no forcing is required, it will clear when you get it to the correct position. Then push the rack as far to the right as you can. You'll have to lift on the rack bushing on the right to get it through the tie rod hole in the body.
Then turn the shaft and extend it all the way to the right, the left side should drop down and out. Then just slide the whole rack to the left to get it out.
Remove the tie rod ends and apply anti seize to their threads to prevent them from locking on the new rack. Count the turns till they come off and when you put them on the new rack, just run them in the same amount of turns. This will get you close to the same alignment. Apply some anti seize to the splines on the new rack's shaft. Put the rack in the same way you took the old one out.
When you get ready to put the column back on the shaft, note that the shaft only fits one place. I find it easier to roughly center the rack (turn its shaft so that it would be steering straight ahead) and then turn the shaft until the notch in it for the pinch bolt faces the hole in the left side of the body where you removed the pinch bolt from. Then you can look and reach in this hole to put the column knuckle back on. Just center the slot in the knuckle on the notch and pull it home. You can now turn the shaft so that you can look through the bolt hole for the pinch bolt and adjust the knuckle up or down so that the bolt can pass through. Don't forget to retighten the pinch bolt inside the car and while you are there, apply some anti seize to the column where it passes through the rubber boot to eliminate squeaks.
While the rack is out, you need to flush the system. Just route the lines to a suitable container and fill the reservoir with power steering fluid. Have several quarts (I use 6 to flush) open and within reach of the reservoir and have someone start the car. Keep pouring fluid into the reservoir and don't allow the pump to run dry. If the pump gets ahead of you, have your assistant turn off the engine and catch back up.
Flush until the fluid runs out clean or you use 6 quarts. Then replace the o rings on the lines where they will attach to the rack. Take care on reassembly not to lose the o rings, you might want to wait till you are actually putting in each line before putting on the new o rings.
On 16Vs you might consider removing and cleaning the plastic reservoir. Early ones, with a white reservoir and black nipples for the hoses, tend to leak at the seams between the white and black parts. Cleaning the seam to remove all grease and grit and applying a bead of RTV silicon and allowing it to dry overnight usually stops these leaks. The hose clamps on the reservoir commonly loosen and seep fluid. There is also a hose clamp on the pump return that needs occasional tightening. Be careful of the reservoir, they get brittle and cost more than they should, should you break off one of its nipples. On 8v's, check the clamp on the small return line on the back of the pump.
After you get it all back together and the tires on, you will need to set the toe and center the steering wheel. Turn the wheels so that they appear to be as straight ahead as possible. Take a tape measure and measure from a point on the front of one front tire to the same point on the other front tire. I use the center thread groove. Then do the same thing from the same reference point on the rear of the front tires.
Adjust the tie rod ends evenly( that is turn one as much as the other to keep the rack somewhat centered) until you get 1/16" difference between the two measurements with the measurement from the rear of the tires being the greatest. Turn the shafts coming into the tie rod ends to adjust. Be sure to loosen the clamps holding the rack boots to the tie rod end shafts before turning the shafts and make sure the boots don't twist when you turn the rods or they will tear. When you get the measurements right, lock down the 22 mm nuts to secure the tie rods. If you feel insecure with your adjustment or notice tire wear after a short time, or the car pulls to one side or the other, have the car properly aligned at a shop.
After filling the reservoir with fluid, start the car and then recheck the level. Then turn the steering wheel all the way from side to side and recheck the level and check for any leaks from the repair.
Go on a test drive and find where the car steers straight, regardless of whether or not the wheel is straight. Then note where the wheel is.
Drive back home and park the car with the wheel in the position it was in when the car drove straight. Pull out the center piece on non SRS cars and loosen but do not remove the 22 mm nut securing the wheel to the shaft. Pull the wheel off by grasping either side of it and rocking it up. The nut will keep you from bashing your face with the wheel when it decides to pop loose. Then remove the nut, loosely place the wheel back on and turn it to the place where the car drove straight. Then remove the wheel and don't turn the shaft. Put the wheel back on so that it is straight and tighten the nut and replace the cover.
On SRS cars, the procedure is the same except you need to remove the airbag to get at the nut. The air bag is held on with 2 either 27 or 30 torx screws that come into it from the back. Turn the wheel so that you can get at them one at a time. Locate and remove these, they won't come all the way out of the wheel, just out of the bag. Then , with the key off, lift up on the airbag and unplug its connector. the connector just pulls straight out of the airbag. As long as you leave the key off, you will not set a SRS code or set off the airbag. Turning the key on while the airbag is unplugged will set a code and necessitate a trip to the dealer to get it turned off. When you lift off the wheel, be sure of two things. One that the turn signal switch is in the neutral position. Two, that the horn contact wiring rests in its hole/slot in the wheel when you put it back on. You have to turn it to line up with the wheel or you will break it by forcing the wheel back on.