Tools and Materials

Tools

Materials

Radiator Flush/Cleaner
Distilled Water
Coolant and Antifreeze
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Note

Product costs, availability and item numbers may vary online or by market.

What’s a Radiator Flush or Coolant Flush?

A radiator flush or coolant flush is a maintenance step for a car or truck. The process of flushing a vehicle radiator includes:

Removing existing radiator fluid
Cleaning sediment, corrosion and debris from the cooling system
Adding fresh coolant and antifreeze to the cooling system

We’ll show you details on how to handle each part of a radiator flush below.

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Key Tools and Supplies for a Radiator Flush

Make sure you have the tools and materials you'll need ready and within easy reach. While flushing the radiator in your car may not require all of these items, they can make the work and cleanup easier.

Screwdrivers
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Combination Wrenches
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Coolant Flush System
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Funnel
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Drain Pan
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Safety Gear
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Mechanics Tool Set
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Coolant and Antifreeze
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Tip

While a radiator flush doesn’t require a fully stocked auto mechanic tool box, a full set of mechanics tools will include the wrenches and screwdrivers you need, as well as other tools, such as ratchets and sockets, that you’ll need for other vehicle maintenance and repairs. You’ll also find that an auto mechanic tool set is useful for other do-it-yourself projects.

Why Do You Need a Radiator Flush?

A vehicle engine generates a high level of heat that can damage the engine components. The radiator, cooling fan, thermostat, water pump, heater core and a series of hoses form a cooling system that circulates coolant throughout the engine compartment. The coolant collects engine heat and releases it through small metal fins or flanges on the radiator.

This system keeps the engine at a good operating temperature. Without a properly operating radiator and cooling system, the heat will cause wear and could result in expensive damage to the engine. Over time, corrosion, deposits and sediment can build up in a vehicle’s radiator and cooling system, keeping the system from working efficiently and correctly. Flushing the radiator cleans out the cooling system and lets the system perform its best.

Coolant vs. Antifreeze

What is antifreeze, and is it the same as coolant? You might use the terms coolant and antifreeze interchangeably, but these liquids serve two different functions. Radiator fluid usually contains both since you typically need to mix water with antifreeze to create engine coolant.

Coolant helps prevent overheating.
Antifreeze helps keep the water in the cooling system from freezing and causing damage. Antifreeze will often provide corrosion protection as well.

You can find antifreeze ready to mix with water and you can also find premixed solutions of antifreeze and water. Check your vehicle manual for the product and mix that’s correct for your car.

How to Flush a Radiator Step by Step

The steps below give you a general procedure for flushing a radiator on a standard gasoline-powered car. Always check your vehicle manual and any manufacturer maintenance information for procedures specific to your vehicle. Follow the use and safety instructions for any radiator cleaning product and new radiator fluid. If you’re not comfortable performing engine maintenance, leave the work to a professional.

Tip

Wear safety goggles and work gloves when working on a radiator You’ll need chemical-resistant gloves when working with radiator cleaner and radiator fluids.

Instructions

Make sure the car is in a safe, level location, with the engine off and the parking brake engaged. The engine will need to run during the radiator cleaning process, so park in an open area with plenty of ventilation.

If your car has an automatic transmission, put it in Park.
If your car has a manual transmission, put it in first gear.

Caution

If you’re working on a car with a manual transmission and have to park on a slope with the front of the car facing down the slope, put the transmission in Reverse.

A radiator cap and radiator overflow tank on a car engine.

Not familiar with your car’s engine? While the engine is cooling you can locate the radiator — a narrow metal component running across the front of the engine compartment. You may be able to see the radiator cooling fins — rows of small, thin metal projections — just inside the vehicle grille.

There will usually be a metal cap on top of the radiator and you should notice a plastic coolant overflow tank to one side of the radiator. On some cars the radiator may be covered and the metal cap may be located on the overflow tank. If you’re unsure of the radiator location, check your manual.

Take a look at the underside of the radiator and look for a drain plug or drain valve. If you don’t see either, look for a large rubber hose connected to the radiator by an adjustable hose clamp.

Once the radiator and fluid have properly cooled, you need to drain the existing coolant/antifreeze mix from the radiator. Wear chemical-resistant gloves and safety goggles to protect yourself from splashes.

If your radiator has a drain valve or plug, place a drain pan under the drain hole and carefully remove the plug or open the valve.
If there’s no drain hole, position the pan under the hose clamp you located above. Use a screwdriver or wrench to loosen the clamp securing the hose to the radiator. Carefully pull the hose away from the radiator.

Allow the radiator fluid to drain into the pan.

Tip

You may want to put a drop cloth under the radiator before draining it to keep any splashes, drips or spills off of your garage floor or driveway.

Caution

Keep pets and children away from the radiator fluid — it has a sweet smell that can be appealing. Take the used fluid to an appropriate recycling or collection center. Check your city or county information for the location of approved sites and disposal requirements.

A person turning the ignition key in a car to start the engine.

Start the engine and turn the heater on high. Let the car run for 10 to 15 minutes. The engine needs to reach a normal operating temperature so the cooling system will circulate the cleaning solution. The solution will loosen corrosion, debris and sediment buildup, allowing it to drain out. It’ll also help flush out any remaining radiator fluid.

Turn off the engine, open the hood and again allow the engine to cool completely — about 1 to 2 hours.

A person pouring a yellowish green coolant and antifreeze mix into a car radiator.

Your vehicle manual should have specifications for the type and amount of coolant and antifreeze your vehicle needs. You can find ready-to-use antifreeze/coolant mixes as well as antifreeze that you pour into the radiator along with water to create the mixture, but only use the products your manual specifies. Open the radiator cap and add the fluid according to the instructions on the bottle.

The radiator overfill tank should have a line indicating the proper fill level for the fluid. Once you’ve added the right amount, replace the radiator cap.

Good to Know

In addition to a fill line, the overfill tank will typically have a line indicating when the radiator fluid level is too low. See your manual for information on maintaining the right level of radiator fluid in your vehicle.

Turn the engine on and allow it to run for a few minutes to circulate the new fluid through the system. Check the radiator — especially the drainage point or hose connection — for leaks. If all looks good, turn off the engine and close the hood.

If the drainage point or hose is leaking, make sure the valve, plug or hose is secure. If the leak continues or if you notice radiator fluid leaking from another location, contact a professional mechanic.

Caution

Clean up any spills or drips of radiator cleaner or radiator fluid.

How Often Do You Need to Flush a Radiator?

The service schedule in your vehicle manual should indicate how often you should flush the radiator. Timing varies by vehicle, but in general you can expect to need a radiator flush and new coolant every 30,000 to 50,000 miles or every 2 to 5 years.

Outside of the recommended timeframe, you may need a radiator flush if:

The temperature gauge on your car consistently shows a high temperature.
You notice a sweet, syrupy smell coming from the engine.
You hear a bubbling sound when the engine starts.
You notice the fluid level in the overflow tank is too low.
The vehicle heater isn’t working correctly.

Keep in mind, while these factors can indicate the need for flushing the radiator and replacing the radiator fluid, they may indicate other serious problems that require a professional mechanic. Have your vehicle checked by a professional if you experience these issues.

Related Tags:

Tools

How to Flush a Radiator

Tools and Materials

Tools

Materials

What’s a Radiator Flush or Coolant Flush?

Key Tools and Supplies for a Radiator Flush

Screwdrivers

Combination Wrenches

Coolant Flush System

Funnel

Drain Pan

Safety Gear

Mechanics Tool Set

Coolant and Antifreeze

Why Do You Need a Radiator Flush?

Coolant vs. Antifreeze

How to Flush a Radiator Step by Step

Instructions

How Often Do You Need to Flush a Radiator?

Related Tags: