2002 Jetta GLX Wagon 12V VR6 5-speed 152K miles
We've owned it since brand new in Aug 2002. For the last year or so its been 'losing' a bit of coolant over time. It had gotten pretty bad the last month or two as I had to check it every night and I was adding about 2 lites of 50/50 per week. In early November I finally got under the car to see if I could see where it was leaking from. It was easier to see where it wasnt. Basically I could see that it was leaking from the bottom of the radiator and from somewhere around the thermostat housing. I decided to replace the radiator, thermostat housing, thermostat, and thermostat elbow as well as all o-ring seals/gaskets used at these components. I also noted that there are several steel coolant 'pipes' (or tubes) that were very rusty on the outside and I decided to replace those as well. I re-used most hoses as they were OK. I used genuine VW parts and ordered everything I needed from 1stVWparts. They were very helpful in helping me figure out the parts I needed. I had done some work on this car in the past (brakes, coilpack, PS pump, etc) but never had worked on the cooling system. I didnt even have a repair manual, just what I could find online (mostly here at the Vortex). This is not intended to be a complete DIY but I hope this is a helpful guide to others.
First thing is to get the car securely on jackstands and disconnect the battery
Disconnect the external hood latch release and remove the grille
Remove the bumper cover. You need to remove the front marker lights housings. Be VERY careful, I broke one when I disconnected the bulb socket from the housing as the plastic gets very brittle over time (in the end this was the only casualty). You dont need to remove the tires to get to the fasteners in the wheel wells just turn the wheels full left to do the right side and vice versa. Also remove the drivers side lower splash shield (not shown). Its held with one screw and two 'reverse starfish' type spring clips that you pry down off their retaining studs.
Remove the styrofoam bumper cushion from the bumper (it pulls straight off), the headlight assemblies, and bumper from the radiator support. Ive seen DIYs where the bumper is not removed but it makes handing the radiator support/radiator much easier as its much lighter without the bumper. Also remove the end of the hood release cable from the hood latch
Disconnect the two fan connectors and the fan switch connector on the radiator (shown
Drain the radiator into suitable containers. We were adding so much coolant the last few months that everything that came out was clean and able to be reused. About 1-1/3 gallons came out