I have had this problem on multiple occasions and if it is your first occurrence that this has happened to you. I am sure you had the same question and reaction that I had, and that is. Why is my car coolant boiling?
There are multiple reasons that your car’s coolant has started to boil. Your radiator could be clogged; your engine fans have not engaged, your coolant to water ratio is imbalanced, a blown head gasket, trapped air, or a faulty radiator cap.
Let’s look further into this and see if we can narrow down your search to find the problem at hand.
What is making my car coolant boil?
Your vehicle’s coolant has now started to boil due to it getting way too hot. I know this is a scary feeling, especially if you have never seen it before. But remember that your engine is substantially hot and needs to be cooled
down to continue working correctly.
Your engine overheating is an excellent example of why you should have a 50/50 coolant to water ratio with your coolant. Due to the temperature, the motor gets to; you need all the help you can get to keep your car running correctly.
Your car’s coolant is starting to boil because it has now become stagnant in your engine and has no place to go. So the coolant continues gaining temperature as it stays in the same location. This is due to either your system not having the correct coolant mix ratio, the antifreeze is not moving, the coolant is not moving fast enough, or you have a blown head gasket.
If the thermostat or radiator is faulty or clogged, then your engine’s coolant will not be moving. If the water pump is blown, then the engine coolant will not be moving fast enough. Then if the radiator fans are not working correctly, they cannot assist the radiator in cooling the coolant down before it gets sent right back into the hot engine.
By doing this, the antifreeze will continue to gain temperature and heat until it is actively boiling. A radiator cap is more vital to your cooling system than many people realize. The radiator cap has a pressure valve built into it.
When the pressure builds up in your radiator, and the coolant is expanding so rapidly, it has nowhere to go. The radiator cap’s pressure valve will open, and this gives this coolant a path to the coolant overflow bottle. In the situation that you have a faulty radiator cap, the pressure valve will not open.
With the pressure valve not open, the pressure will continue to grow as the coolant continues to sit and gain temperature until it boils. If you do have any trapped air in your cooling system due to a previous cooling system repair, then you will need to burp your cooling system.
Bleeding this air is quickly done by opening your coolant reservoir lid and starting your vehicle. Once your car gets to operating temperature, then turn your air on in your car to full blast and make sure it is on the highest heat setting. Doing this will start cycling the coolant through your heater core and pushing any built-up gases out of the system.
Leave your vehicle running until all of the bubbles have exhausted out of the coolant reservoir. When it is steady with no bubbles, then your system has been bled of air.
Last but never least, the dreaded head gasket. Replacing a head gasket is one of the most common causes of coolant “boiling.” That is because the head gasket is either worn or damaged from the car being overheated. You can damage the head gasket if you cause the vehicle to overheat without repairing the cause of the overheating problem.
In the case that the head gasket is damaged, it will let pressure from the cylinder into the cooling system. These gases slip by the head gasket allowing this pressure to escape the cylinder. It will seem the coolant is boiling, but it is escaping gases that are causing bubbling.
If you are looking for a way to find out if it is the head gasket or not open your engine oil fill cap. After you open the engine oil fill cap, look under the lid and look to see if there is any white and frothy oil sitting under there. White and bubbly oil is an excellent indication that there is water in your oil.
What should I do if my coolant is boiling?
In the situation that your engine’s coolant begins to boil, you need to find a safe place to pull over and stop the vehicle. You do not know what is causing the coolant to boil at this moment.
So the first thing you need to do is to check the temperature of your engine. To do this, you need to look at your temperature gauge on the driver gauge cluster. If your engine temperature is in the red area, you will need to turn your car off immediately.
If your vehicle is not overheating, but the coolant is still boiling, you will need to open the lid to the coolant reservoir. Please take notice that I said the coolant reservoir and not the radiator. You never want to open your radiator cap unless your vehicle is cool and has not been running.
This will prevent any pressure and heat buildup in the system, which saves you a big headache. By opening the lid of the coolant reservoir, you are giving the air pocket in your system a way to be ” burped” out of the system.
Is it bad for my car to have the coolant boiling?
Yes, it is terrible for your car to have the coolant boiling. Without knowing why the coolant is boiling, you will not know if the problem is the engine overheating or you have a blown head gasket.
Remember to look at your engine temperature gauge when the engine coolant is boiling, and this will tell you the vital information you need to diagnose your car’s problem.
How can I fix the coolant from boiling?
First, you need to find out why it is boil in, to begin. Once you find out which part is at fault, then you can replace this part to correct the problem. Make sure to follow the other sections to diagnose the part at fault.
The average cost for a head gasket is $500 – $850. The cost of the repair is why many people sell their vehicles if it needs a head gasket replaced and their car is not worth much, to begin. I cannot count how many cars I have
seen though that diagnosed for a head gasket, and it was something else in the system.
My brother thought he had a blown head gasket as well one time as he called me to freak out about the price. Remember, when it comes to a high proceed evaluation from a mechanic shop to get a second opinion.
Everyone is not perfect, and sometimes, a misdiagnosis can happen. So before you give yourself a health problem for worrying too much about the issue, get a second opinion. In the case, someone says it is a head gasket think about the common symptoms of a blown head gasket.
Does your vehicle have the coolant boiling inside the coolant reservoir? Is your cars exhaust white? The last time you were driving your car, was your vehicle running rough?
Take off the engine oil fill cap on your engine and turn it upside down, what color is the oil inside the lid? If the oil is not whitish, and you have none of the other problems I just stated, then you do not have a blown head gasket. So it is now the time to diagnose what the problem is.
How can I prevent the coolant from boiling in the future?
The best way to prevent your vehicles coolant from boiling in the future is by keeping up today with your maintenance intervals.
Maintenance of your car is vital in the operation of your vehicle. So if you stay up to date with your car, then you will be able to take care of the small problems early enough to prevent more significant issues.
Thank you for reading my article, and I hope you enjoyed it and it helped you with your problem. Make sure you subscribe to my YouTube channel for more DIY Auto repair and flipping cars for profit videos! Thank you again, and I hope you enjoy my next piece!
