DIY

How to Replace a Faulty Radiator

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You’ve done all the checks needed and you’ve determined that your cooling system troubles stem from a faulty radiator – now what? You have several options depending on how severe your problem is. Let’s look at how to maintain the radiator, flush it, repair cracks and replace it.

How Do You Maintain a Radiator?

Every car has a maintenance schedule offered by the manufacturer. To care for your system, you want to replace the coolant typically between 25,000 to 40,000 miles. This prevents issues with coolant delivery.

As soon as you notice any trouble with the engine temperature, you want to have the radiator inspected. It’s possible to repair the tank, flush old coolant, replace leaking hoses or swap out the entire radiator.

To prevent issues with coolant delivery, it’s best to replace the coolant between 25,000 to 40,000 miles.

How Do You Flush a Radiator?

If you think a clog is the problem, you can attempt a radiator flush.

Step 1: Your engine must be cool. Don’t attempt to open the petcock or radiator with a warmed engine. Before performing any work, tap on the radiator to ensure it’s cool.
Step 2: Put your vehicle on jack stands so you can access the bottom of the radiator. Place your container underneath.
Step 3: Open the petcock to drain all of the coolant.
Step 4: Once it is drained, close the petcock. Now, fill the reservoir with water. Run the engine for a few minutes.
Step 5: Run the engine for a few minutes so the water circulates. The engine shouldn’t get too warm.
Step 6: You need to drain the radiator a second time.
Step 7: You want to repeat this flush a couple of times.
Step 8: Once all of the bad coolant is flushed from the engine; you can fill the system with fresh coolant.

How Do You Seal a Leaky Radiator?

If you find a leak, there are ways to seal it. Try these steps to see if any work for you.

Step 1: Begin by replacing a leaky radiator cap. This is probably the easiest fix you might need.
Step 2: Apply a commercial sealant. This isn’t a permanent fix but merely helps you stop the leak or slow it down long enough to get repairs. Make sure the engine is cool before you pour it in the radiator. Make sure the coolant is topped off.
Step 3: Use epoxy for small cracks. If you see the crack, you might be able to use some epoxy. Make sure you clean the area first. Then, cover the entire crack with epoxy and let it dry overnight before running the car.

Apply a commercial sealant if you find a radiator leak. This isn’t a permanent solution but helps you stop the leak or slow it down long enough to get repairs done.

Cost to Replace a Radiator

The worst case scenario means you need to replace the radiator. This isn’t a job that everyone can tackle. It requires some expertise and a good amount of tools. Most radiators cost between $200 and $600. If you need someone to replace it, you will need to factor in labor costs as well.

Tools Needed for Radiator Repair

Tips for Replacing a Radiator

Before you begin, there are a few things to keep in mind.

Don’t attempt to work on your radiator while the engine is hot. Wear protective gear anytime you work on the cooling system.

Steps to Replace a Radiator

If you plan to replace the radiator yourself, these are the steps you will want to follow.

Prepare the Vehicle

Step 1: Raise your vehicle and provide proper support. Use jack stands in the front and wheel chocks in the rear. Don’t forget to apply the parking brake.
Step 2: Drain all of the coolant out of the radiator into an approved container. Remove the car’s lower radiator hose or open the petcock valve.
Step 3: Remove the reservoir hose. You can loosen the hose clamp with a screwdriver or pliers, depending on the design. Then, twist the hose and pull it away from your radiator.
Step 4: Use your pliers or screwdriver to disconnect the upper radiator hose.
Step 5: Take off the lower radiator hose. Use your screwdrivers or pliers and then pull it away from the connection.
Step 6: Push in the tab and pull back to disconnect the cooling fan electrical connector.
Step 7: Take off the cooling fan mounting bolts with a socket, ratchet and extension.
Step 8: Take off your cooling fan.
Step 9: Use your flare nut wrench to remove the transmission cooler lines from the radiator.
Step 10: Remove the mounting bolts on the radiator. Use your socket and ratchet or wrench.

Replacing the Radiator

Step 1: Take out the radiator.
Step 2: Mount your new radiator in the same position.
Step 3: Install the radiator mounting bolts. Tighten them down.
Step 4: Use a flare nut wrench to connect the transmission cooler lines to the radiator.
Step 5: Mount the cooling fan and install the bolts.
Step 6: Install the cooling fan connector.
Step 7: Connect the lower radiator hose and tighten.
Step 8: Connect the upper radiator hose and tighten.

Bleed the air out of the system through the bleeder valve, by using a cooling system vacuum fill tool or by running the engine while the radiator cap is off.

Step 9: Attach the radiator reservoir hose and tighten.
Step 10: Fill your radiator with fresh coolant according to manufacturer specs. Make sure the drain petcock is closed before filling.
Step 11: Bleed the air out of the system through the bleeder valve, by using a cooling system vacuum fill tool or by running the engine while the radiator cap is off. Each car has a different procedure, so make sure you check your repair manual for complete instructions.
Step 12: Lower your vehicle.
Step 13: Make sure you always recycle your coolant at a local shop.

Fix Your Radiator Right

Whether you think you can simply replace a cap or you have to install a new radiator, it’s important that you get the job done right. A faulty radiator leads to many other problems and you don’t want the expense.

Time after time, customers came to me at the dealership wondering why they had to replace multiple cooling system parts. In almost every instance, it was due to neglect. When you ignore the first warning signs, you put your entire system at risk. If that’s what you choose to do, then be prepared for the consequences that follow.

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Author

Brian Jones

ASE Certified Master Tech and Parts Specialist

Brian Jones spent more than 20 years working as an ASE Certified Master Tech and Parts Specialist at multiple dealerships. Currently, he lives with his wife and children in a suburb of Dallas, TX. He spends his time dreaming about pickup trucks, muscle cars, Jeeps and anything related to motorsports. He works with numerous dealerships around the country as a consultant. In his spare time, Brian likes to visit new places and hopes to travel the world.

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