So after months of watching my driveway covered with PS fluid, I decided to rebuild the steering rack on my 2000 1.8t Passat. Although I was losing a ton of fluid, I never let the pump go dry. If yours did go dry several times, you might want to consider replacing the pump at this time as well. You're doing this at your own risk and I am not responsible for any damage. I followed this thread on how to remove the rack:
so I won't go over that. EXCEPT I would not drain the fluid the way SausageRocket described in his thread. Again, I don't think it's ever good idea to run the pump dry. Actually, I did not drain my fluid at all, I only detached the hose from the rack at the pump, but if I would do it again, I would skip that step. If your rack was as bad as mine, you already have the fluid all over anyway. Besides, there is no pressure in the rack unless you're turning the wheels or the engine is running.
Also, before you remove the rack, you need to mark the relationship of the control valve shaft and the housing while the wheels are pointing forward (rack centered). This is very important because if you don't, your steering wheel will be way off. I skipped that step and at the end ended up removing the steering wheel and readjusting because it was about 30 degrees off. Not the hardest thing to do, but really unnecessary and you can avoid it just by making those marks. You can make those marks also when you get the rack out, but you got to make sure the rack is centered.
Before you start you'll need to get a rebuild kit. I got mine from RockAuto. They have Edelmann and Gates kits for both Koyo and ZF racks. There are other places that sell kits as well (O'Reilly, etc.....) and I couldn not find any info if one is better than another. I got the Gates kit, around $50 shipped, although one of the clamps they sent for the driver side boot was too big. Also there was a snap ring that didn't fit (you can safely reuse the old one unless you destroy it while removing). Minor things, but worth considering. I'd recommend getting new rack boots as well, as they are usually not included in these kits, lots of brake cleaner and lint free cloths, and some locktite thread sealant. Also, you'll need some "Molybdenum disulphide lithium based grease", although if you can find that for this application, let me know. The closet thing I found was this.
These two links helped me a lot, although those racks are a bit different than mine,but check them out:
Power Steering Rack Rebuild
So after you got your rack out, remove the pressure tubes:
Mark the relationship of the spring cap to the housing and remove it:
Remove the spring and the guide. If the guide is not coming out, it's ok, you can get it out later after you remove the rack:
Remove the screw from the centering hole:
Remove the rack housing cap:
and the lock nut while counter holding the other side with a wrench:
Remove the snap ring:
and gently tap the valve out:
On the other side turn the end stopper until you see the end of the wire:
Pull the end out and keep turning the stopper until the wire's out and remove the stopper:
Pull the rack out:
Now you have everything apart and you can start replacing the seals and rings.
The valve has one oil seal and four teflon rings. I used a blade to cut through the rings, but make sure you do not make any scratches or dings. Whatever you do, do it carefully because a slightest scratch will cause the valve to not function properly:
Then you have to put new teflon rings. They need to stretch first, and there is a special tool to do it (you can see what it looks like in the pdf link I posted). This is how I did it. Make sure you do not break or damage them. They will be loose afterwards, but that is ok for now:
To compress them, I wrapped them tightly with electrical tape and used a hose clamp and left them like that for a couple of hours:
Similar procedure with the rack. Replace the o ring and install a new teflon ring. Wrap it tightly with electrical tape and give it some time to compress:
Then remove the oil seal from the rack bushing. I clamped it down and with a screwdriver removed the seal. Mae sure you're not scratching the surface:
This is where you should be placing your screwdriver:
Replace all four o-rings:
and the one on the spring cap:
Now you have to remove two seals inside the rack housing. This is the hardest part and you really have to be careful not to make ANY scratches where the seals are. Here is one:
Wrap a screwdriver a tape so you don't damage the housing. I bent the tip of the screwdriver a bit so I could reach the seal easier. You'll be tapping on the spacer:
The other seal is in the middle of the housing, you can barely see it. I used a larger wood dowel to knock it out and it did take a while to get them out:
After you get all that out, clean the housing and make sure it's dry. I used a lint free microfiber cloth and brake cleaner. When everything is clean and dry, coat the new seals and spacers with PS fluid (the kit did not provide new spacers, but the old ones looked great so I reused them). When pounding them back into their places, make sure you push them far enough. I measured the length of the cavity before putting the seals and then after. If the difference is exactly the thickness of the seal and the spacer, you're good, If not, keep pounding, till they are COMPLETELY in. And do this gently, you do not want to destroy the seals. Find a socket that fits and also wrap it with the tape, so you don't scratch the surface inside the housing. The seal that is in the middle of the housing (for the rack), took a while to get completely seated. Be precise with this, don't assume it's close enough, because that's just not good enough, it will fail. Also, if you do not pound the valve seal all the way in the housing, the valve will not fit and you won't be able to install the snap ring.
After you got the housing seals in, you can install the rack. Cover the teeth with the tape and gently push it through, making sure you don't scratch the housing. Then install the rack bushing (make sure which way it goes in). Use the end stopper to push it in, just as much as it's needed to secure the stopper with a new wire that should be in your kit:
Grease the gear and the rack with molybdenum disulphide lithium based grease and install the valve, making sure those marks you made in the beginning on the housing and the valve shaft are aligned. Pound it in and secure the clip. Grease the bearings at the lock nut, tighten the nut (check the attached pdf for the specs), install the cap (coat threads with Locktite), rack guide (grease it first), spring, and the spring cap (coat threads with locktite sealer and align your marks).
Install tie rod ends and boots and your rack should look like this:
One thing left is the hex screw in the centering hole. You need to make your own screw to keep the rack centered while installing, which should look something like this:
Afterwards make sure you replace it with the original screw. DO NOT FORGET THIS!!! Otherwise you'll destroy your rack.
I hope this will help guiding you. I might have left out a step or two, but don't hesitate to ask me to clarify things.