These steps should work on all 2000-2005, 3400 or 3800
Flushing the radiator
1.Park your car on a level surface. Wait for the radiator to cool down, then put on a pair of safety glasses and rubber gloves. You don't want used antifreeze to come into contact with your eyes or skin.
2.Place a drain pan beneath the drain valve on the radiator. Any deep pan will work, whether it is an oil pan, a kitchen pan, or even a dishpan.
3.Open the drain valve on the radiator and drain the used antifreeze coolant into the pan. While draining, open the hood of the car and remove the radiator cap by first pushing it down and then twisting it off.
4.Allow the radiator to drain fully, then close the drain valve. Pour the used radiator fluid into a funnel that drains into a regular two-liter bottle. Fill the bottle with fluid and cover it tightly. This and all the other drained radiator fluids must be taken to an automotive
shop or hardware store for recycling.
5.Fill the radiator with water from a hose, then drain it again into the pan. Inspect the water for rust, sediment, dirt or debris. The drained water must be clear before you continue; continue to fill and drain until only clear water drains out.
6.Mix up an approximate 50/50 solution of new antifreeze and water in a five-gallon bucket. Use a half gallon of antifreeze to start, and mix in the same amount of water. Place the funnel in the radiator and pour the mix into the funnel. Completely fill the radiator with the mixture. Note: If you do not completely remove the Dex-cool you must put Dex-Cool back in. Do Not Mix Dex-Cool with any other anitfreeze.
7.Start the engine and allow the radiator fluid to flow throughout the system, bleed the air out at this time. Run it for approximately 15 minutes, then shut it down and allow the engine to cool off. When the engine is cool, remove the radiator cover and top off both the radiator and the coolant overflow tank with the 50/50 mix.
Bleeding the air
With the engine running and the heater on high.
Open the bleeder valves on top of the thermostat housing, you might have one over on the heater by-pass pipe next to the passenger side motor mount, but I've seen a few cars without them so maybe you don't have one.....be very gentle, they're made of brass and twist off very easily.
Always bleed it with the car running. If normal bleeding is not getting the air out, use this method:
Raise front end about 8-10" off the ground so that the radiator and reservoir are higher than the heater core(remember, air rises to the top), fill reservoir and run engine for about 10 minutes with heater on high. Turn off engine, allow to cool for a couple of minutes and check reservoir. If below the full mark, repeat process. Do this until the reservoir stays at full mark(usually 2-3 times).
Here is a video I found, its low quality but.......