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Car Overheating After Blue Devil – Why And How To Fix It

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Car Overheating After Blue Devil

Are you experiencing car overheating after using Blue Devil? This is a common problem that many car owners have faced. Blue Devil is a popular sealant that is used to fix leaks in the head gasket, engine block, and other parts of the engine. 

But why is your car overheating after Blue Devil? First of all, this overheating indicates that the sealer has blocked small water pathways in the engine, clogging the radiator, or jamming the thermostat. It’s also possible that the gasket sealer did not have the desired effect, leading to the persistence of overheating.

In this article, we’ll take a look at what causes the problem. Keep reading to find out how best to fix this problem and get back on the road safely. 

Reasons Why Your Car Is Overheating After Blue Devil

To keep your engine from overheating, use Blue Devil, or BD as it will be referred to throughout this article. While Blue Devil may temporarily fix leaks, it can also cause additional problems when the sealant is not properly mixed or applied.  

Reasons Why Your Car Is Overheating After Blue Devil

However, if there are existing issues with your cooling system or if your automobile still overheats after using this product, there are several potential causes to consider.

Blocked Water Jackets

One issue that may occur is that the Blue Devil has the potential to block the water jackets in the cast iron engine blocks. And this would prevent coolant from running through the engine and will ultimately lead to the vehicle overheating. This is one of the major problems arising after the BD application.

Clogged Radiator

The use of Blue Devil may result in internal blockages within the radiator. This clogs its core tubes and hinders coolant flow, thereby decreasing its cooling performance. 

Blue Devil is a thick liquid that can clog small passageways and cause a build-up of pressure in the cooling system. Hence, this can cause the engine to overheat, and you may notice steam coming from under the hood.

Clogged Radiator

The Leak Is Too Big To Be Sealed

Blue Devil is designed to seal small leaks, and if the leak is larger than the product can handle, it will not be able to fix the problem.

Product Not Used Correctly

BD is meant to be added to the coolant system. But if it’s put into the oil or transmission fluid, it can cause damage to those systems and lead to overheating. 

Car Overheating After Blue Devil

Additionally, using the product in an engine that is already damaged or has clogged passages can compound the problem. The product is intended to seal leaks, it cannot clear clogs.

Defective Thermostat

A bad thermostat will cause your car to get too hot even after you’ve used the BD. Many car owners have had bad experiences with this chemical sealant blocking, running, or sticking their thermostats. 

It can emanate from small chunks of sand and concrete in and around the thermostat and lower hose. A malfunctioning thermostat that regulates coolant flow can restrict it, resulting in overheating if not addressed. 

Defective Thermostat

When it breaks, it can’t always keep track of the temperature of the coolant, and the coolant can’t flow. 

Impaired Radiator Cap

If your radiator cap doesn’t work right, your engine cooling system won’t have enough pressure to keep your car from overheating. 

Enmeshed Air In The System

If coolant flow is restricted due to trapped air in the system, the engine will overheat even when you’ve applied Blue Devil.

Possible Fix For An Overheated Car After Blue Devil Application

After the gasket sealant, a thorough diagnosis of your vehicle will reveal the precise reason for the overheating. We’ve already covered some of the most likely suspects in the preceding section, so you know where to start looking.

However, it is recommended that you have a professional mechanic check your car for the reason of the overheating and make the necessary repairs. So, if you can, the most likely way to solve this problem is DIY. Now follow the steps below to fix yourself. 

Possible Fix For An Overheated Car After Blue Devil Application

Step 1. Begin by performing a FULL radiator flush or cleansing to remove all of the “junk” that is causing problems in your engine. With as much distilled water as you can, flush it out. The system as a whole must be clean!

Step 2. You might also want to take the heater hose off where it goes in and out and flush it out. This is helpfulⁿ, as the heater core may also have been clogged.

Step 3. Follow the right way to fix the head gasket, which is to get a new one. No additive will help fix the head gasket for good, so you will have to replace the gaskets.

Step 4. Replace your radiator. The BD may have clogged your radiator cores with its chemicals. You may also need to repair a clogged radiator.

Step 5. Also, change your thermostat. It could be stuck or open after using the sealer product, causing the gauge to show temperatures that aren’t right.

Step 6. Get a new pump for water. Once the BlueDevil disaster has started, the next thing to go will be your water pump, so you’ll also want to get a new one in time.

Step 7. A tune-up would also be required for this repair. We propose replacing your engine’s spark plugs and wiring.

Step 8. Inspect the serpentine belts and the timing as well. If you haven’t taken care of them in a while, you should also do that now. You don’t want to think about putting so much money into the engine only to lose the timing belt!

Possible Fix For An Overheated Car After Blue Devil Application
If your car is overheating after using a product like Blue Devil, you may be interested in our articles on car overheating when the AC is off and car overheating when the AC is on and idling. These articles provide valuable information and solutions to common car overheating issues. Whether you’re dealing with overheating when the AC is off or experiencing issues with overheating when the AC is on and idling, our team at Car Problem Solved is here to help.


Many questions have been asked by some people regarding the Blue Devil sealant. Let’s provide answers to a few of them. 

Q: Can Blue Devil Damage Your Car?

No, this product will not cause any damage to your car. The ingredients used to manufacture it are very friendly and good for your car’s maintenance.

Q: Why is my car overheating after using Blue Devil?

Because it blocked the water jacket, also, the thermostat got stuck closed and the cooling apparatus for the engine got plugged up as well. 

Q: Will Blue Devil stop my car from overheating?

Of course, the Blue Devil helps to curb car overheating problems because it helps to raise the coolant’s capacity to transmit heat. 


I hope we’ve helped you to understand why your car overheats after applying the BD. To recap, if you have overheating issues after adding Blue Devil, the product has likely clogged your radiator or engine coolant passages. Hence it can be fixed by flushing the coolant system and other solutions discussed in this article.  

It’s also important to keep in mind that using a sealant like Blue Devil is not a substitute for proper maintenance and repair of your vehicle. If you’re experiencing leaks or other issues with your engine, it’s best to have a qualified mechanic diagnose and fix the problem.

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