Thanks to : VgRt6 (Gary) for help working out the minutiae of this procedure.
This DIY describes how to replace the thermostat housing and coolant distribution pipe (AKA crack pipe) on the MKIV VR6 motor. This covers most of the weak spots in the coolant distribution system. If you have a leak in one spot, consider replacing as much as you can afford. At the very least, replace all o-rings and the thermostat. Next most important, replace the sensors, housing, and pipe. If you have not done so already, you might as well replace the water pump. Check hoses for condition and replace as necessary. If you do not replace the plastic parts, at least check them very carefully for stress cracks and repair with JB Weld or other high-density epoxy product as necessary.
Spark Plug Wire Puller
5mm Hex socket or similar. It should be short (no long t-shaped wrenches)
10 and 13 mm sockets
Various socket extensions
Flathead screwdrivers (thin and wide)
Phillips head screwdriver
Channel-locks or similar wrench for hose clips (short handles good)
Thermostat Housing Seal
ECU Temp sensor
2 sensor O-Rings
Crack Pipe (a2t2 billet pipe or stock)
Screw-style hose clamps (5 at 2 inch max dia, 1 at 1 inch max dia)
Alot of paper towels
RTV Silicone Sealant (optional)
Threadlocker or Anti-Sieze (optional)
Get the lock carrier assembly to the service position using this DIY:
Lock Carrier to Service Position
Precautions and Obvious Stuff:
Wear gloves and skin covering clothing at all times, and consider eye protection. Change your clothing if it becomes soaked in coolant. Coolant can soak through skin if left for long enough. G12 is extremely poisonous stuff. It contains Ethylene Glycol, Diethylene Glycol, and Sodium Hydroxide, just to name the most dangerous ingredients. It has a sweet taste and smell, and is attractive to children and animals for this reason. Even a small amount can cause irreversible damage to your liver and kidneys. Ethylene Glycol in the bloodstream catalyzes into several harmful intermediaries, mostly acids, ending in things like Oxalic Acid that can lead to crystals in your urine. The early stages of poisoning feel similar to ethyl alcohol intoxication. I strongly recommend you abstain from alcohol consumption while working with coolant for this reason. If you even suspect that you have been poisoned: take a shower, get yourself out of the garage, and call your doctor. Early intervention could save your life and has a high success rate. Death from glycol poisoning is SLOW and PAINFUL. You have been warned!
Modified by darisd at 4:42 AM 1-13-2006