If your car is suffering from overheating issues, a radiator flush might do your car good. On average, you’ll need about $150 to do a radiator flush. The cost will vary depending on labor rates and your car’s make and model. We’ll give you the ultimate guide to radiator flush cost, what it is, how it can help you, and of course, whether or not you need it. Let’s begin.
How Does Your Car’s Radiator Work?
Before we start, we always like to explain how the car component in question works. This will give you a better understanding of how they work, why it needs repairing, and how they need to be repaired. In this case, we’ll learn about how a car’s cooling system works, which at its heart lies the radiator. As you probably already know, your car has a few liters of coolant that run through the engine to cool it down during operation. This is necessary since the engine gets very hot – it’s basically running on controlled explosions.
The coolant will rest in a reservoir and the radiator, and then it circulates via a water pump throughout your engine. It will then make its way back to the radiator, where it will flow through thin metal fins. These fins will allow heat to dissipate from the coolant, cooling them down before they circulate through the engine once again. Additionally, there’s usually a fan that blows air across the radiator to help dissipate the heat.
There are other components as well, such as the thermostat which is a valve that regulates the flow of the coolant. Then there’s the radiator pressure cap, which regulates coolant flow into the reservoir. When the engine is running, the coolant will get hot and pressure within the system will increase. When this pressure increases, the coolant will flow into the reservoir tank, avoiding leaks. Needless to say, when one of these components fails, you will experience overheating problems. Whether it’s because the coolant flow is disrupted, or because a coolant leak is present.
Here’s a quick video on how your car’s cooling system works:
Why Do You Need a Radiator Flush?
So, now you know how it works, why exactly do you need a radiator flush? That’s because rust and deposits will build up inside your radiator and the cooling system over time. When this happens, it could create blockages and disrupt the flow of coolant in your car’s cooling system. Eventually, this will lead to overheating problems since the coolant isn’t flowing efficiently. This is where a radiator flush can help your car.
A radiator flush will clean the insides of your car’s cooling system. Removing debris, corrosion, and clearing blockages from the cooling system.
Radiator Flush Process
The radiator flush process will require your mechanic to drain the car’s cooling system. They will need to do this after the engine and coolant have cooled down. This is because a hot cooling system is pressurized and it will be dangerous to drain the cooling system while it’s hot, so your mechanic will have to wait for about an hour or so for the system to cool down.
Once the engine has cooled down and the cooling system has been drained, then your mechanic can begin the flush process. They will insert a mixture of water, detergent, and coolant into the radiator. Then they will let the engine run so that this mixture can circulate through the cooling system. In this process, the mixture will clean the cooling system of any debris, rust, and other blockages it may have.
Once done, your mechanic will drain the cooling system once again. Afterward, they’ll refill your radiator with new coolants, make sure there aren’t any leaks, and your car is good to go.
When to Do a Radiator Flush
Most new cars won’t require a radiator flush anytime soon. This is because their cooling system is still brand new, and it doesn’t require any cleaning. It’s once your car reaches around 100,000 miles where you’ll need to start considering a radiator flush. It can help to keep your cooling system clean and in good shape. However, speaking from experience, be careful where or how you choose to do a radiator flush. I’ll explain why in a bit.
Of course, if you experience overheating problems, you may want to consider a radiator flush. However, I personally will check first if there are faults with any of the cooling system’s components. The thermostat, the water pump, and the radiator hoses are some of the parts that will fail over time.
Bottom line: if you see overheating issues, troubleshoot first and see what the problem is. If all other components are fine, then you probably need a radiator flush.
Quick Note About Radiator Flush from Personal Experience
I recently had a radiator flush in my 2011 Mitsubishi Pajero Sport with 110,000 miles on the clock. The flush was recommended by the auto repair shop even though the car had no overheating issues. But since the car was quite old, I agreed to the recommendation. After a week I found out that the car was leaking coolant and having overheating issues. The first leak came from one of the radiator hoses, and the second one came from the water pump. Which led to an expensive pump replacement.
As far as I can tell, the problem stems from a poorly done radiator flush. The flush managed to get rid of blockages, but the rust and deposit buildup within the system wasn’t properly drained, and a lot of them remained in the system. Additionally, a lot of the rust and deposits were now “loose” and coolant can easily erode them, and then they will circulate in the system. This leads to damage and leaks from various components, including the hoses and the water pump.
The problem was rectified by using only water for my cooling system, rather than a mixture of water and coolant. Water doesn’t erode the rust in the system as easily as coolant does. While water has a lower boiling point, this is mostly fine since I don’t live in a cold area and I don’t require the antifreeze properties of an engine coolant. Since then, the car has been working just fine.
This is not to discourage you from doing a radiator flush, but rather, make sure you choose a good auto repair shop to do the job. If you’re doing it yourself, be sure to follow the guides and not miss any steps to avoid expensive repairs.
Troubleshooting Overheating Issues
Now, if you’re experiencing overheating issues with your car, it’s best to diagnose the root of the problem first before you do a radiator flush. There’s no point paying for a radiator flush when there’s actually a different problem with your cooling system. Here’s how to troubleshoot an overheating engine:
1. Check Coolant Level and Leaksp
The first thing to do when you have an overheating problem is to check the coolant level. Locate the coolant reservoir and check the coolant level. The reservoir will have a maximum and minimum marker, if it’s below the minimum level, then top up with coolant and water if the coolant isn’t a premix. Afterward, let your engine run and drive it around if you want to. If the engine overheats again and the coolant level drops rapidly, then you have a leak in your cooling system.
In this case, park your car and inspect the underside and your car’s engine bay. Try to locate where the leak is coming from, and replace or repair the leaking part. One of the hoses may be loose and will need to be tightened. If there’s a crack in one of the hoses or a leak from the water pump then you will need to replace them to stop the leak.
If the coolant level is normal and there are no leaks, other components may be at fault.
2. Check the Radiator Cap
The radiator cap seals the cooling system and makes sure that the system is pressurized. It also controls the flow of coolant into the reservoir tank. Radiator caps are designed to last a lifetime, but they may fail if subjected to heavy rust. If the cap is faulty, you may see bubbles inside your radiator. This is because the cap isn’t sealing the system properly which causes air to enter the system, forming bubbles in the coolant. When this happens, the pressure inside the cooling system will decrease and causes the coolant to be less efficient in cooling the engine.
If you see bubbles in the coolant and suspect you have a faulty radiator cap, replace it with a new one. They should be no more than $50 for most cars. However, you will need to get rid of those air pockets as well. This is where a radiator flush will come in handy, but you can also do this by simply removing the radiator cap and let your car run without the cap for 15-20 minutes.
Afterward, refill the coolant if necessary, and then install the new radiator cap. See if the overheating problem persists. If the bubbles still appear, you may have a head gasket leak. This problem will usually be accompanied by other symptoms like blue or thick white smoke coming from the exhaust, misfiring problems, and rapid engine oil drain.
If you think the radiator cap is fine, let’s move on to other components.
3. Check the Radiator Fan
Most cars will have a fan sitting either behind or in front of the radiator. These fans will usually turn on immediately when you turn on the engine and will ramp up when it detects the car is overheating. If the fan isn’t turning on, this can affect the radiator’s ability to dissipate heat from the coolant, which then affects the engine temperature.
There are two types of radiator fan: manual and electric. A manual fan is powered by the serpentine belt. Check if the belt is still installed properly or if it’s loose. If the belt is not in place, then the fan won’t run and you will need to reinstall it. If the belt is loose, then the fan won’t spin as fast as it should. In this case, you will need to tighten the serpentine belt. Keep in mind that once a serpentine belt is loose, you will probably need to replace it soon.
If your car has an electric fan, then you will need to disconnect the electrical connection to test it. Use a voltmeter to test if there’s power going to the wires. If the voltmeter reads around 12volt, the power connection is fine, which means you will need to test the fan. To do this, expose the two metal pins inside the fan’s connector. Take two wires and connect one to the positive battery terminal and into one of the pins. Then take the other wire and connect it to the negative battery terminal and into the other pin. If the fan doesn’t spin, then you will need to replace it.
4. Check the Water Pump
The water pump is what’s responsible for pumping coolant from the radiator into your engine. If this fails, then the coolant won’t flow and won’t cool the engine. Like the radiator fan, there are two types of water pump: mechanical and electric. The mechanical water pump is powered by the serpentine belt. Check if the belt is loose or has come off, in this case, you will need to either reinstall it or replace it altogether.
The electric power pump is a bit more difficult to diagnose. The problem is that there are no OBD codes for a faulty electric water pump, which means you can’t scan the car’s OBD to verify the problem. Additionally, the water pump’s location is usually harder to reach than the radiator fan, meaning it will be difficult to diagnose it the same way you did with the radiator fan. The worst part? You never know when these electric water pumps could fail. I had an experience with a five-year-old Mercedes C-Class where the water pump just failed randomly for no apparent reason.
The easiest way to diagnose this would be to see if the coolant is flowing when you turn on the engine. Open the radiator cap and let the engine run, see if the coolant is flowing or staying in place. You can also place a rag on the top of the top radiator hose, and then press your hands against it. See if you can feel coolant flowing through the hose. Don’t do this with your bare hands as it can get very hot.
If the coolant isn’t flowing, then the water pump may be at fault. However, the thermostat may also be at fault. Which you will need to check:
5. Check the Thermostat
The thermostat controls the flow of coolant from and into the engine. During the start of the operation, it will close the main valve so that the engine to get into operating temperature. At that point, the main valve will then open to let coolant circulate into the radiator, keeping the coolant at an optimum temperature. If this main valve is stuck closed, then the coolant can’t flow into the radiator, leading to an overheating coolant and engine.
Diagnosing a thermostat can be tricky and requires removing it from the system. However, if your car has a mechanical water pump or you’re sure it’s working, see if the coolant is flowing. Let your engine get to operating temperature and touch the top radiator hose. A cold hose means that the coolant isn’t flowing. If you’re sure the pump is working, this means the thermostat is stuck closed and isn’t letting coolant flow into the radiator.
If you’re still not sure, then you can remove the thermostat and check it with a boiling pot of water. Here’s how:
6. Replace the Temperature Sensor
Finally, if you’ve checked all the components above and they’re fine but you’re still having overheating problems, then it’s possible that you have a faulty temperature sensor. This sensor usually sits somewhere near the thermostat. It detects the temperature of the coolant and then feeds that information into the temperature gauge. A faulty temperature sensor might display incorrect temperature on the gauge or may not work at all.
They rarely fail, but most components in a car are not fail-proof, and this sensor can fail. If you can’t seem to find the root of the overheating problem, try replacing the temperature sensor. They should cost around $150 – $200 for most cars including labor.
Radiator Flush Cost
Now you know how your car’s cooling system works, why a radiator flush may be needed, and how to troubleshoot an overheating car. So, how much does a radiator flush cost? On average, the radiator flush cost is about $150. This already includes the four gallons or so of coolant to refill the cooling system, the cleaning solution, and the labor cost. Keep in mind that the radiator flush cost may be more if the repair shop charges higher labor rates.
Again, radiator flush isn’t necessary when your car is still under 100,000 miles. After that, you may need to do it from time to time to keep the system clean. Most experts will recommend doing it every 10,000 miles. Or, your mechanic may also recommend this as part of a routine service. Just keep in mind to choose a good auto repair shop to make sure they can do the job properly. A badly done radiator flush may actually do more harm than good, as I’ve learned the hard way.
The radiator flush cost is relatively inexpensive, and the highest estimate is just a little over $200. Still, you can reduce the radiator flush cost by doing it yourself. It’s a relatively easy job to do, here’s how:
Reducing Radiator Flush Cost: DIY
You can do a quick flush if you don’t have a lot of time, or a more thorough flush if you feel like it. We’ll discuss the process for the latter but they’re essentially the same process. Here’s what you will need:
What You Will Need to Do a Radiator Flush
- About 2 gallons of radiator flush.
- 3-4 gallons of coolant. Check with your owner’s manual to see what type of coolant you should use and how many gallons you will need.
- 4-6 gallons of distilled water.
- Buckets, pans, and empty gallons or containers to contain the old coolant.
Once you have those, you can begin the process:
How to Flush a Radiator
- Add a gallon of the radiator flush fluid into the reservoir tank and let your engine run. You can drive it for a couple of days if you want.
- Drain the cooling system. You should get rid of any coolant that is both in the radiator and in the reservoir tank. Some cars may have a drain plug, but others will require you to disconnect the bottom radiator hose. To drain the reservoir tank, disconnect the hose that connects to the radiator and use a pump to get the coolant out.
- Clean the reservoir tank with high-pressure water. This step is optional but recommended.
- This next step will require some effort but is optional. Remove the thermostat from the cooling system, as this will provide a clear flow for the flush fluid to recirculate.
- Once the system is drained, reconnect all the hoses and start filling the system with about 2.5 gallons of water diluted with the radiator flush fluid. The dilution is usually 3 parts water, and 1 part flush fluid. Fill both the reservoir tank and the radiator.
- Turn the engine on, and let it run for about 10 minutes.
- Once done, drain the system once again. Repeat steps 5 and 6 a couple of times necessary.
- Refill with the system with the appropriate type and amount of coolant. Your car is good to go and your cooling system is now clean!
Here’s a guide from ChrisFix on how to do a full cooling system flush:
If you feel like the full flush takes too much effort, here’s another guide from ChrisFix on how to do a quick flush:
Radiator Flush Cost: In Conclusion
A radiator flush isn’t necessary for a new car. But once your car reaches that 100,000-mile mark, you may want to consider it. A properly done radiator flush can help to keep your cooling system healthy. The radiator flush cost is relatively inexpensive at just around $150 for most cars. Of course, your radiator flush cost can be cheaper if you do it yourself. This way, you only have to pay for the flush fluid and new coolant and don’t have to pay for labor.