How to Clean a Radiator
How to Clean a Radiator


A radiator is an important part of your car engine's cooling system, allowing water or coolant to circulate through small tubes that are cooled by incoming air. This liquid cycles around the hot engine, cooling off the metal parts by moving the heat into the radiator to be cooled before circulating again. Buildup from the heated metal and the evaporating water can clog the radiator over time, while radiator fins can accumulate dirt and road grime, as well as bugs, pebbles and other objects from the road.

Many manufacturers suggest that you clean the outside of your car radiator at least once a year. You should also give your radiator a complete flush once every five years to improve the functionality of your vehicle's cooling system.

To avoid damaging your radiator and potentially your engine, your choice of cleaning product is important. Avoid using vinegar, because the acetic acid makes metal susceptible to rust. Additionally, bleach should never be used, because sodium hypochlorite (bleach) will corrode metals such as steel and aluminum. This can result in damage to the vehicle's intake manifold, block, or engine head as well as degrading rubberized gaskets and seals.

A safer option to harsh chemicals and solvents, Simple Green Pro HD Heavy-Duty Cleaner is non-corrosive and safer for cleaning aluminum, stainless steel and other metals. The professional-grade, engine-compatible formula breaks down tough grease, oil, road grime and other automotive fluids, making it ideal for cleaning your radiator.

Directions for Cleaning a Radiator:

Radiator Fins

Check your vehicle Owner's Manual before cleaning radiator. Always follow manufacturer's complete instructions for cleaning and maintenance. Make sure radiator is cool to the touch before cleaning.

  1. Dilute cleaner. In a large container, mix 1 part Simple Green Pro HD Heavy-Duty Cleaner to 3 parts water. Add the solution to a dilution bottle with a spray nozzle.
  2. Apply Simple Green Pro HD solution. Spray the radiator with the Simple Green solution.
  3. Remove foreign objects. Use a soft bristled brush to gently remove any little rocks, bugs or other items caught in the radiator fins. If the fins are bent, use a flathead screwdriver to gently bend them back into place.
  4. Rinse. Using a low pressure hose or bucket of clean water, gently rinse the radiator from the back side. If water doesn't run clear after rinsing, repeat steps 1-3.
  5. Dry. Allow to air dry.


Check your vehicle Owner's Manual before flushing radiator. Make sure radiator is cool to the touch before opening radiator cap.

  1. Dilute cleaner. In a large container, mix 1 part Simple Green Pro HD Heavy-Duty Cleaner to 15 parts water, enough to fill your radiator. Most 4-cylinder vehicles have a capacity around one gallon.
  2. Drain radiator. Place a drainage pan or other container beneath the drain cock opening on your radiator. Remove the fill cap from the top of the radiator. Use gloves or pliers to open the drain cock on the bottom of your car's radiator and drain it. Dispose of the fluid properly. Replace the drain plug.
  3. Add cleaner. Pour the cleaner slowly into the fill hole on the top of the radiator. Close radiator cap. Let the mixture remain in the radiator for 5 minutes.
  4. Start engine. Turn on the vehicle and run the engine for 5-15 minutes to allow cleaner to cycle through the engine. The motor needs to warm up to operating temperature to allow the thermostat to open, and let coolant flow from the radiator to and through the motor and back.
  5. Drain cleaning solution. Turn off the engine. Open the drain cock and allow the cleaning mixture to drain. Then replace the drain cock. Dispose of the used cleaner properly.
  6. Rinse. Fill radiator with water (if possible, use distilled, non-mineralized water). Turn on engine and allow it to idle for five minutes. Then turn off the engine, open the drain cock again and allow the water to drain. Repeat process until there is no foaming. Then replace the drain cock.
  7. Add coolant. Add the recommended amount of coolant to the radiator.


Baker Farrow
Cleaning Trade
Collins Industrial
Harvey Distributors
Independent Oils
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