Does White Smoke Always Means a Blown Head Gasket? (Answered!)


Many car owners are wondering if white smoke from the tailpipe always means a blown head gasket? Do not confuse the white smoke that you usually see when you first start the car in the morning. That is condensate and that’s totally normal. We are talking about excessive white smoke from the tailpipe.

I reached out to a couple of local mechanics to see what their thoughts are on this matter. What I found out was very interesting…

Does White Smoke Always Means a Blown Head Gasket?

Does White Smoke Always Means a Blown Head Gasket

Does white smoke always mean blown head gasket? Yes. Excessive white smoke coming from the tailpipe always means that your cylinder head gasket is blown. The cylinder head gasket is located between the cylinder block and cylinder head and has the purpose to seal the engine’s combustion chamber and preventing coolant or oil from leaking anywhere else. A blown head gasket will allow for coolant to enter the combustion chamber and burn with the air and fuel, resulting in white smoke from the tailpipe.

In normal conditions, the coolant travels through specially designed passages around the cylinder head and cylinder block. With the help of the cylinder head gasket, the coolant only circulates around the combustion chamber, and never goes in it.

However, if the head gasket is blown, it allows for the coolant to escape and leak into the combustion chamber and then get burned off with the fuel mixture. This will result in white smoke from the tailpipe. Depending on how bad the head gasket is blown, you might see a little bit of constant white smoke from the tailpipe, or excessive white smoke.

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In some rare cases, when an engine is overheated badly, the cylinder head can develop a crack and allow for coolant to leak into the combustion chamber from there and get burned off with the fuel mixture. However, in most cases, it is a blown head gasket that causes the coolant leak.

So, if your vehicle is losing coolant, but there are no obvious signs of leaking and you see excessive white smoke exiting the tailpipe, make sure to check the head gasket. Instead of dismantling your engine to visually inspect the head gasket, there is another way.

Can You Test For a Blown Head Gasket?

Can you test for a blown head gasket? Yes. You can test for a blown head gasket by using a combustion leak tester. This tester kit allows you to perform a chemical experiment on the coolant which tells you if that coolant has combustion chamber gases in it. If it does, that means that the coolant has been into the combustion chamber, meaning, your head gasket is blown and it is allowing coolant to enter the combustion chamber.

If your vehicle isn’t running right, your engine might have a blown head gasket. But how do you know if your head gasket is really blown? Now, the head gasket fits between the head and the block of the engine. So, you can’t see if it’s leaking because it’s inside the engine. That’s why you need a combustion leak tester kit. It will tell you whether or not you have a blown head gasket.

I got this combustion leak tester from amazon.com. It is pretty simple to use. The kit comes equipped with a test tube and a test liquid. The first thing that you need to do is open the radiator cap. Then, get a turkey baster and remove at least one cup of coolant. You don’t want the testing tube to rest on the coolant directly because it can give you some false results.

Then, place the bottom half of the tester tube and stick it in the radiator. Pour some of the tester fluid. There should be a line that tells you how much liquid to pour. Place the middle part of the tester tube and again pour some liquid into it.

Put the top part of the combustion leak tester tube and start your vehicle. Come back to the tester kit and press the bulb a couple of times to start sucking air in. The liquid will then check if combustion gases are getting into the cooling system. If there are any, the liquid will change colors from blue to yellow. That is a clear indicator that the head gasket is blown.

Can You Have a Blown Head Gasket Without Overheating?

Does White Smoke Always Means a Blown Head Gasket

Can you have a blown head gasket without overheating? Yes. It is possible to have a blown head gasket without overheating. This can happen in the winter months when it’s cold outside and you only drive your car for short trips under 10 miles before it has the chance to reach the optimal engine temperature. However, the engine would be burning the coolant due to the blown head gasket, and eventually, your vehicle would lose all of the coolant.

This actually happened to my 2007 Hyundai Santa Fe. It was December and it was pretty cold outside. I only used this car to go to work and back which was around 3 miles each way. So, the engine didn’t have the chance to reach the optimal working temperature and then overheat. Instead, it kept burning all of the coolant little by little, until May. It got pretty hot one day in May and while I was driving to work, the engine just overheat.

What happened was because I was driving the vehicle for only short trips, it lost all of the coolant over time and it didn’t overheat because it was cold outside. On the very first hot day, the engine reached the working temperature sooner and it overheated because it had zero coolant in it.

However, if you drive your vehicle for longer trips and your head gasket is blown, regardless of the temperature outside, the engine will overheat once it loses all of the coolant. Depending on how bad the head gasket is blown, it can take anywhere from a thirty-minute drive to a three-hour drive for all of the coolant to leak. If you notice on time that the temperature needle is going up, you can prevent your engine from overheating and possibly thousands in repairs.

Can You Have a Blown Head Gasket Without Losing Coolant?

Does White Smoke Always Means a Blown Head Gasket

Can you have a blown head gasket without losing coolant? No. You can’t have a blown head gasket without losing coolant. The head gasket seals the combustion chamber and makes sure that coolant and oil flow only around the combustion chamber and not in it. A blown head gasket will allow for coolant to get inside the combustion chamber and get burned. This results in your vehicle losing coolant. However, depending on how badly the head gasket is cracked, the leaking could be very little or severe.

The head gasket is located between the block and the head of the engine. Its job is to make a pressure-tight seal between the different systems that are at play in your engine. For starters, the head gaskets make sure that the compression from the combustion chambers doesn’t leak out. Then, there are oil passages as well as coolant passages. These passages ensure that both oil and coolant are traveling around the combustion chamber and not in it.

However, a blown head gasket can no longer hold compression. Also, a blown head gasket can’t keep oil from coolant, so you can end up having oil in your coolant, coolant in your oil, or coolant in your combustion chamber. That is why it is impossible to have a blown head gasket without losing coolant. It can only result in a minor leak that you won’t notice, but there will definitely be a leak.

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Hi there. I am a certified Automotive Service Excellence (ASE) mechanic since 2018 and a car detailer for 10 years.

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