Just did this because my radiator opened up this morning on my 99.5 Jetta TDI so I took the day to replace it as well as the thermostat. I didn't find any helpful DIYs online so I just made a quick write up to help people. Here are the steps I generally went through (sorry I don't have pictures of the process): Start with at least the front of the car lifted a good amount, at least so the wheels are several inches off the ground. 1) Remove the bumper cover and headlights. Google how to do it if you don't already know. 2) Remove the skid plate and side splash guards if you have them. 3) Drain the radiator by unscrewing the drain plug on the bottom driver's side rear of the radiator. Remember to unscrew the reservoir to allow a full drain. 4) Remove both the top and bottom hoses from the radiator. DO NOT MESS WITH THE HOSES THEMSELVES, as they are attached to plastic fittings which have to come off anyway. This is accomplished by using a flat head screw driver to pull the wire loop up from each fitting, and then pulling DIRECTLY away from the fitting. Do not twist or otherwise torque the fitting during removal... it will not help and you might snap it (it's made of plastic). 5) Unplug the auxiliary fan plugs and the coolant temp plug. The aux fan plugs are kind of tricky; there is a button on one side of each that unlatches the plug. Find it and unlatch it before any yanking occurs. 6) Now that you have everything drained and ready for removal, it's time to remove the rear fan shroud. Unclip the hoses at the bottom of the shroud, and then remove the four torx screws at each corner of the shroud. They are not very accessible, just a warning. Once you've removed the screws, yank and tug the shroud out from the bottom. This may take some swearing, so just swear more and it'll come right out! Haha really though, just take your time and ease it out. 7) NOW you can remove the radiator... right after you remove 8 screws. There are two sets of screws that you will have to remove from the front of the car. One set has black torx heads and is the actual radiator. The other set (forming a smaller pattern within the first square) has silver torx heads and attaches the radiator to the A/C condensor. Remove all of them. From here, everything should be free to move. Remove the rubber/plastic radiator supports from each corner of the radiator, and wiggle the thing out. Again, the radiator should come out the bottom of the car. 8) Transfer over the coolant temp sensor. This (so I read) requires a 30 mm deep socket, but it's a low enough torque that 1 1/8" socket will also do the trick with no problems. Also keep track of the direction of the rubber/plastic radiator support thingies, as their direction matters during reassembly. 9) Installation is generally the reverse of removal. The only tip I'd give is to screw in the radiator before screwing in the attachment screws to the a/c condensor. This will make alignment much, much easier. 10) For filling, I just referred to the many DIYs for flushing your radiator. No use to recreate the wheel, so just Google it. And that's it (or at least what I remember)! For my first time it took me about 5 hours from start to finish including the thermostat/flange replacement. I'm not an expert and I wasn't exactly rushing, so you can probably achieve or beat this time even going at a comfortable pace. Enjoy!