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How to Change a Car Radiator

Dan Ferrell writes about DIY car maintenance and repair. He has certifications in Automation and Control Technology and Technical Writing.

Change or fix your car radiator at the first sign of damage.

Change or fix your car radiator at the first sign of damage.

How to Replace a Radiator in a Car

Replacing a car radiator requires a few things:

  • A few simple tools
  • Draining the coolant from the system
  • Gaining access to the radiator
  • Removing the radiator
  • Installing the new radiator
  • Filling the system with fresh coolant
  • Purging the system

This project falls within the skills of the average car owner and will definitely help you stretch your car maintenance budget. Within this guide, you'll find a systematic approach to this task that works on most vehicle models.

However, whether you already have some experience or not, it's a good idea to have the vehicle service manual for your particular car's make and model on hand. The manual will help you deal with components you may need to remove to gain access to the radiator in your particular car, and then purge the system after refilling it with coolant.

If you don't have the repair manual, buy one like this Haynes manual from Amazon. The manual is an excellent investment. It'll help you with future maintenance, troubleshooting and common repair projects; so you can save time and money throughout the year. Haynes manuals come with step-by-step procedures, photos and illustrations for many projects you can do yourself at home.

So, let's get started with that radiator.


Tools You'll Need

I. Draining Coolant From the Radiator

II. Removing the Radiator

III. Refilling and Purging the Cooling System

IV. Extending Your Radiator Service Life

You can use a special funnel to add coolant to the system to prevent air pockets in the system.

You can use a special funnel to add coolant to the system to prevent air pockets in the system.

Tools You'll Need:

Wrench set

Shop rags

Ratchet, extensions and socket set

Slip-joint pliers

Floor jack, jack stands and 2-wooden blocks, if needed

Drain pan - for 2 gallons or more


Line wrench (aka flare nut wrench)

Two small plastic sheets and two rubber bands, if needed

New antifreeze — or premixed coolant, if needed

I. Draining Coolant From the Radiator

For this project, choose a level area with enough room around your vehicle. With some car models, you have to lift the front to gain access to the radiator's drain plug or valve (petcock).

  1. First, make sure the engine is cool. Trying to remove the radiator cap on a hot engine may cause severe skin burns.
  2. Disconnect the negative battery cable from the battery and secure the cable to prevent it from accidentally touching the battery post while you work on your car. Wrap the terminal in a shop rag, if necessary.
  3. Remove the cooling fan shroud, if your vehicle has one, using a ratchet or wrench.
  4. Disconnect the coolant reservoir hose attached to the radiator neck. Usually, you need to slide a hose wire clamp at the radiator end towards the reservoir using a pair of pliers. Then carefully pry off the hose from the fitting.
  5. Check if you can reach the radiator drain plug located at the bottom and to one side of the radiator. If not, you may have to lift the front of your vehicle with a floor jack and safely secure it with a jack stand on each side. Chock the rear wheels and set the parking brake. Also, some vehicles have a lower shield that needs to be removed to gain access to the bottom of the radiator.
  6. Place a large drain pan on the floor aligned with the radiator drain plug.
  7. Open the radiator drain plug, and loosen the radiator cap. Let the coolant drain out of the radiator completely.

    NOTE: If the drain plug doesn't work or has become rusted or the radiator doesn't have a drain plug, disconnect the lower radiator hose instead. Check the procedure to disconnect the hose in the following section.

  8. After the coolant has finished draining from the radiator, reinstall the drain plug.
  9. Remove the drain pan, and cover the pan to prevent contamination, if you plan to reuse the same coolant. Otherwise, put the coolant in a closed container for later recycling and store it in a safe place.
Replace old, damaged or worn out parts when installing the new or rebuilt radiator.

Replace old, damaged or worn out parts when installing the new or rebuilt radiator.

II. Removing the Radiator

If you need to remove several components to gain access to the radiator, you may want to refer to your vehicle repair manual so you know how to remove and reinstall them.

  1. Remove the air cleaner duct, if necessary, to gain access to the radiator and electrical fan. You may need a screwdriver for this.
  2. Unplug the cooling fan electrical connector.
  3. Unscrew the fan mounting bolts and lift the fan out of the engine compartment.

    NOTE: On some vehicle models, though, you actually need to remove the radiator and the fan(s) as an assembly because of the reduced space in the engine compartment.

  4. Disconnect the upper and lower radiator hoses from the radiator. You can use a pair of slip-joint pliers to slide off the spring clips that secure the hoses to the radiator fittings or a screwdriver, depending on the type of clamp used on the hose.
  5. Then, use the pliers to break the hose grip on the radiator fitting by twisting the hose just a few degrees back and forth, while pulling the hose off the spout.
  6. On some models with automatic transmissions, you need to disconnect the cooler lines from the radiator. You'll see two thin metal lines that connect to the side or bottom of the radiator. Place a drain pan under the lines to collect oil from the lines and radiator, and use only a line wrench to unscrew the single nut securing each line to the radiator. This way you avoid damaging the nut and the need to replace the whole line.
  7. Once disconnected, cap the oil lines to prevent contamination of the system. Use a clean piece of plastic sheet and a rubber band to secure the sheet to each line end.
  8. Now, depending on your particular model, you may need to tilt the radiator forward to disconnect the air conditioner condenser from the radiator. Use a line wrench to disconnect this line as well. But do not remove the condenser from the engine bay.
  9. Unplug any sensors attached to the radiator.
  10. Double-check for any other lines, electrical connectors, or devices you may need to disconnect or remove that may prevent you from removing the radiator.
  11. Detach the radiator by unscrewing the radiator top brackets, side mounting screws, hold-downs or any other mounting clips holding the radiator in place.
  12. Carefully lift the radiator out of the engine compartment.
  13. Remove any debris from the radiator mounting area.
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Read More from AxleAddict

Some radiators can be repaired by a specialty shop, depending on the type of damage and radiator construction material. However, if you've decided to replace the radiator, match up the old radiator to the new one, and transfer any necessary parts from the old unit to the new one. Just keep in mind that some new radiator replacements have a lower thickness because of an improved efficiency design, but height and width remain the same. If you have the correct replacement, install the new or rebuilt radiator following the previous procedure in reverse order. Just be careful when lowering the unit in place to prevent bending any cooling fins.

The next video may give you some visual clues about replacing the radiator as well.

III. Refilling and Purging the Cooling System

After installing the radiator, it's time to refill it with coolant. You may want to replace the coolant as well, if it's already close to two years old or five, depending on the particular antifreeze you use for your vehicle. Consult your car owner's manual or repair manual to make sure you are using the correct antifreeze type for your system, and mix it with distilled water only. If the coolant you drained previously is relatively new, make sure it's clean. If necessary, use muslin to strain the coolant to remove as many foreign particles as possible.

After refilling the system with coolant, check for leaks and purge the air from the system to prevent the formation of air pockets that can overheat the engine. Air pockets lead to hot spots that can damage head gaskets, cylinder walls or the cooling system itself. This is necessary on many newer car models where the radiator neck sits at the same or lower level than the rest of the cooling system.

Many modern vehicles use a bleed valve to purge the air from the cooling system. You may find the valve on the thermostat housing attached to the engine and the upper radiator hose, if not, consult your vehicle service manual.

If you want to bleed the air through the bleed valve, consult your owner's manual or repair manual for the proper procedure for your model.

On some modern vehicle models, the radiator doesn't have a cap. But they have a coolant recovery tank that functions as a coolant reservoir as well. Fill the system with coolant through the recovery tank up to the "Cold Full" mark. Then, start the engine and add coolant as needed. Any air in the system will be purged through the recovery tank.

A Simple Method to Bleed Air From the Cooling System:

Whether your vehicle comes equipped with a bleeder, purge valve or none, you still can use one of two alternative methods to prevent air from settling in the cooling system.

Jacking up the car to purge the cooling system:

  1. After having refilled the system with coolant, jack up the front of the vehicle to raise the radiator neck above the rest of the cooling system or cylinder head.
  2. Safely support the vehicle on jack stands.
  3. Remove the radiator cap and then install it back by turning the cap to its first lock position.
  4. Connect the negative battery cable to the battery, and turn the heater to the highest setting.
  5. Start the engine and allow the thermostat to open. You'll know the thermostat has opened when the temperature rises on the upper radiator hose. This will cause the coolant to circulate and the air to escape through the radiator cap.
  6. Allow the air to escape through the radiator cap and then shut off the engine.
  7. Add more fresh coolant through the radiator neck to top it off, and wait a few minutes to allow the thermostat to close. The coolant temperature will drop below 190° F (88° C).
  8. Squeeze the upper radiator hose to expel any trapped air.
  9. Lower the front of the car and check the coolant level and add more if necessary to bring it to the correct level.
  10. Tighten the radiator cap.
  11. Check the coolant level throughout the week to make sure there are no leaks, and the coolant level is correct.

Using a special funnel to purge air from the system:

Another highly recommended way to prevent introducing air while refilling the system is to use a special funnel like this a spill-free funnel kit, which you can find on Amazon. When using the funnel, you don't need to raise your vehicle or use the bleed valve to purge the air from the system. The funnel will purge the air for you.

Purge the air from the cooling system after refilling the cooling system.

Purge the air from the cooling system after refilling the cooling system.

IV. Extending Your Radiator Service Life

Replacing the radiator yourself can save you hundreds of dollars in labor costs. And doing the job yourself may not be as hard as you may think. When replacing the radiator: First, keep track of the sequence of the steps you're using to remove the radiator so that you can follow those steps in reverse order during the installation procedure. Second, connect everything back correctly. And finally, purge the air from the cooling system, if necessary, to prevent engine overheating. Once you have the new radiator installed, replace the coolant at your recommended manufacturer intervals to help prolong your new radiator's service life. And keep this guide handy to help you next time you need to remove or replace a car radiator.

This article is accurate and true to the best of the author’s knowledge. Content is for informational or entertainment purposes only and does not substitute for personal counsel or professional advice in business, financial, legal, or technical matters.

© 2016 Dan Ferrell

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