How To Flush A Car's Coolant System

Posted on: 1 April 2015

Your car's coolant system keeps the engine cool and working in both hot and cold temperatures, and if not properly maintained, will result in the poor performance of your vehicle. How often the coolant system needs to be flushed will depend on the make and model of your vehicle, so check the owner's manual for specific guidelines. Thankfully, flushing your car's coolant system is a fairly simple process, and can be done in a short time with the right tools and knowledge.

Before You Begin

You'll need a large bucket, about 2 gallons (or 8 liters), a funnel, an adjustable wrench, and empty bottles with lids that you can use to store the old coolant. You may also need a star or flat headed screwdriver, depending on your car.

You should also park the car on a flat surface, and ensure that the parking brake is on while you're working on your car to prevent accidents from happening.

Flushing the Coolant System

  • Locate the drain valve at the bottom of the radiator. It should be near the front bumper of the car, but will depend on your car. Check the owner's manual if you're unsure.
  • Place the bucket underneath the valve, and then use the screwdriver or socket wrench (again, depending on the model of your car) to open the drain valve. Wait for all the liquid to drain out of the valve, and then close it again.
  • Use the funnel to pour the coolant into the empty bottles, and ensure that their lids are tightly screwed on.
  • Open the hood and find the radiator pressure cap. It is usually clearly labeled, and sticks out of the top of the radiator. Fill the reservoir with water.
  • Run the engine for ten minutes, keeping an eye on the temperature gauge to ensure that the engine does not get too hot. Once ten minutes are up, or the temperature gets too high, turn the car off and allow the engine to cool.
  • When the engine is cool (which can take about a half hour), drain the water out of the radiator into the bucket. By running the engine with just water in the coolant system, you help clean out any gunk or built up debris in the system, improving your engine's efficiency.
  • Close the drain plug after all the water has been drained out and fill the radiator with coolant. Check your owner's manual to see what proportion, if any, of coolant to water that your vehicle requires. Once the radiator is full, replace the pressure cap and close the hood.
  • You can now drive normally, but be sure to keep an eye on the temperature gauge to ensure that your coolant system is working properly. Also, check the coolant levels after a few days of driving normally to ensure that the system is still topped up, and add more coolant if necessary.
  • Be sure to dispose of the old coolant properly, as it is toxic to animals.
  • Talk to experts like Automotive Specialties for more information.