Dodge Caravan Coolant Change Procedures

In a perfect world, one would be able to do a complete fluid flush and replacement by simply draining the [ engine coolant ]ngine and radiator at the same time, and refilling them with fluid; but it's not a perfect world. You will need to take this job in three stages; draining the radiator, diluting the engine coolant and draining perhaps the most overlooked system on any car, the heater core which, including the core lines, can contain more than half the amount of fluid contained in the radiator itself.

Drain the radiator while the coolant is cold; simply open the brass petcock valve at the bottom left or right corner and drain the fluid into a sealable 5-gallon container. You can expedite the process by opening the coolant cap, which allows air to enter the radiator core. With all the fluid emptied, refill the radiator with distilled water, leave the cap open, and run the engine until it reaches operating temperature. The goal here is to get the thermostat open, diluting what coolant remains in the engine.

At this point you're working with an open cooling system boiling to the brim with hot death-juice; eye and hand protection is mandatory, and keep anyone you have any affection for well away from the action.

With the engine coolant diluted and sitting in the radiator, repeat the drain/refill procedure. Restart the engine and bring it all back up to temperature again.

The Caravan's (and every other car's) heater works like a radiator in reverse. Hot engine coolant flows through the heater core, through which the HVAC fan pushes air. Air picks heat up from the engine coolant, which must be flushed with the rest of the system. While some might advise removing the heater core drain-back line, the fact is that running the heater during the second flush will accomplish the same task with less mess and aggravation.

If you're using a store-bought caustic radiator flush solution, this is the time to introduce it. With the engine at operating temperature and the heater running, the caustic solution will work its way through the entire cooling system to rid it of any built up minerals or rust. Allow the engine to run for at least 10 minutes after you introduce the cleaning agent.

Repeat the drain and refill procedure two more times to rid the system of cleaning solution and dissolved minerals, which will manifest as a milky haze in your previously clear coolant. Once the coolant runs clean and clear, drain four gallons of water from the radiator and replace it with fresh antifreeze. When all's said and done, you'll wind up with at least 10 gallons of highly toxic radiator water, which should be disposed of at your local fluid recycling center.