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Radiator Coolant Flush

Antifreeze and coolant are two commonly confused concepts. Ethylene glycol in antifreeze is only one part of today's car coolant delivery systems. Water is what takes care of most of the cooling in your engine. A coolant mixture is basically water and propylene glycol antifreeze.


The coolant in your radiator isn't just playing it cool. Coolant protects against freezing. This is why it is commonly referred to as antifreeze. Coolant also protects against corrosion and helps lubricate your water pump. 

There are many antifreeze additives to help with corrosion protection and lubrication. Always check the coolant additive warranty before use. Follow the antifreeze manufacturer's instructions for temperature ranges and mixture ratios to match your climate. 

Some types of engine coolants need to be replaced yearly to avoid any engine damage which can be costly to your cooling system. Thoroughly flush the radiator system for maximum efficiency when it's time to replace coolant. Using radiator flush kits can be of some help but always at an added cost. 

Locate the engine coolant sensor, coolant expansion tank and coolant heater on your car. This will allow you to perform periodic visual inspection before any radiator flush and fill services. 

You know you have a problem with the coolant temperature sensor when your temperature gauge rises or drops erratically or if your radiator fan won't shut off. 

During a visual inspection, look for warning signs that should not be ignored, such as:

  • Low coolant light
  • Leaking hoses or pipes
  • Smell of antifreeze in the car
  • Noisy coolant pump
  • Corroded or leaking radiator
  • Coolant in exhaust
  • Antifreeze leaking into oil

Also, test your radiator cap to make sure it is working properly. 

Remember: Prevent spills by using catch pans and trays during antifreeze disposal. Beware of antifreeze poisoning for humans, animals and the environment. Proper antifreeze recycling where available, is good practice. Never remove a hot radiator cap.



Parts you'll need:

  • Funnel
  • Catch containers
  • Utility knife
  • Basic hand tools (wrenches, sockets, pliers, etc.)
  • Antifreeze tester
  • Antifreeze coolant
  • Radiator flush
  • Radiator flush kit


Safety comes first

Every vehicle is different. When it comes to maintenance and repairs, always follow the vehicle's owner's manual. 

Safety should be your number one priority. Don't smoke, drink alcoholic beverages, or wear a necktie while working on the car. Watch out for hot objects, sharp instruments, hazardous materials and other potential safety hazards in and around your workspace. 

Don't work with a Philips when the job calls for flat. Substituting tools can compromise your safety or a vehicle's performance. 

Finally, when the fun turns to frustration, or if the job requires specialized knowledge beyond your capabilities, please do not attempt it yourself. Talk to a professional mechanic or installer. The last thing we want is someone getting hurt.


Before you begin

Everything you need for this job can be found at Parts-King. Ask your the King for assistance. It's better to have extra spare parts ready for anything that might need to be replaced. The last thing you want to do is go shopping when you have the car up on the jack. 

When taking parts apart, be organized. Keep similar parts together in a safe place where they won't get lost and layout parts in a way that will allow you to put them back in the same order. 


How to flush coolant from a radiator

  1. Find the right catch container for your vehicle. Be prepared for at least two gallons of coolant. The vehicle should be cool and properly secured. Apply the parking brake or use wheel chocks.
  2. Carefully remove the radiator cap. Open the drain petcock on the bottom of your radiator*. Move the catch container as coolant flows to prevent spillage. Drain and clean reservoir overflow according to manufacturer's instructions.

  3. If your coolant is dark or brown in colour, you or the previous owner waited much too long and your system will require a chemical flush. If your coolant is still green, orange or yellow you can skip step 4.

  4. Close the petcock and pour in the radiator flush chemical. Add water according to the manufacturer's instructions. Start and run the engine until warm, then repeat step 2.

  5. With the radiator and overflow empty, install the flush kit's "T" fitting according to the manufacturer's instructions. Connect the hose. Drain the attachment. Back flush with the hose until the water runs clear. Drain the radiator. Close the petcock.

  6. Follow the coolant mixing instructions and fill radiator to one inch below the filler neck. Look for the filler line. Start and run the vehicle without the radiator cap, and top off as the engine warms up. Reinstall the radiator cap.

  7. Fill reservoir to proper line.

    *You might have to remove the lower radiator hose. Check your vehicle repair manual.