How To Flush A Radiator To Keep It In Good Condition

The summer driving season is soon to begin. If you are planning to drive to distant places on vacation, you should make sure your car is in tip-top shape to avoid having car trouble on the road. Making sure your car is prepared for long trips gets more important as the car gets older. One problem that can arise is the car overheating, because the radiator cooling system is filled with rust and sludge. Here is how you can remove the rust and sludge to reduce the chance that your car will overheat while driving far away from home.

You Will Need the Following Auto Parts:

  • New Coolant Fluid
  • Jack
  • Jack Stands
  • Five Gallon Pail
  • Hose
  • Water

Let the Coolant Cool Down

Do not work on the radiator if the coolant is still hot. You'll want to let the car cool down for at least a couple of hours after you've been driving. Hot coolant is under pressure, and if you remove the radiator cap while the coolant is hot, you can suffer serious burns if it gushes out of the radiator and onto your body.

Draining the Radiator

If your car is low to the ground, you should jack up the front end to give you room to reach under the radiator to open the drain valve, and to fit a container to catch the coolant as it drains. Make sure you place jack stands under the car to hold the car up so the car won't drop if the jack fails.

Place a collection container under the drain valve – a five gallon plastic pail works well – and open the drain valve underneath the radiator. The drain valve has a wing-nut on it, and is typically the only nut on the underside of the radiator (sometimes the wing-nut is covered by a plastic cap that you need to remove before you can loosen the wing-nut and open the valve). Let the coolant, sludge, and rust drain into the five gallon pail.

You'll have to flush the system with water to remove any remaining coolant, sludge, and rust. Take a garden hose and put it into the top of the radiator. Run water through the system until it runs clear through the drain valve. You may have to use two five gallon pails if it takes a lot of water to completely flush out the radiator.

Once the radiator is flushed, close the drain valve, and refill the radiator with new coolant.

The old coolant is considered a hazardous material and should not be poured out onto the ground. Instead, take the old coolant to an auto shop and have them properly dispose of it for you – some shops might charge a couple of dollars for this.