A blown head gasket is rarely a clean break; instead, it looks like a physical breach, tear, or missing section on the gasket, often causing severe symptoms in your engine’s fluids and performance.
Bad head gasket symptoms
While it's possible to drive with a blown head gasket it certainly isn't recommended. Once the seal is blown, pressure in the combustion chamber is lost and you'll feel a significant loss of power. If your blown head gasket is causing coolant to leak, your engine is far more likely to overheat.
The easiest, most definitive way to check for a blown head gasket at home is by using a combustion leak detector (or block tester). This $30–$45 kit draws air from your radiator to check for exhaust gases, turning the blue test fluid yellow if the gasket is leaking.
Because a blown head gasket shares symptoms with other common engine problems, it is easily misdiagnosed. Overheating, white exhaust smoke, and milky oil can also be caused by a cracked engine block or cylinder head, a leaking intake manifold gasket, a failing heater core, or external coolant leaks.
A professional can perform a compression test or a chemical test to identify exhaust gases in the coolant to confirm a blown head gasket.
What are the symptoms of intake manifold leak?
Compression leak between cylinders: Rough idling, misfires, and a loss of power may indicate that the head gasket has failed between cylinders. This causes a loss of compression as compression leaks from one cylinder to the next and can cause exhaust gasses to flow back into the intake.
A blown head gasket is one of the most labor-intensive and expensive automotive repairs you can face. The gasket itself is relatively cheap, but the cost comes from the extensive labor required to access it and the specialized machine work often needed.
A temporary head gasket fix typically involves pouring a chemical "stop-leak" sealant into your radiator to bridge small cracks or blown sections. While these additives can buy you time (sometimes months or thousands of miles), they are not a substitute for a mechanical replacement.
You should not drive a car with a blown head gasket, as it can cause catastrophic engine failure. If you absolutely must, you can only drive a few miles to reach a safe location or a repair shop, provided you constantly monitor the temperature gauge and the coolant level.
Depending on the type of damage, a head gasket sealer can help fix a blown head gasket. If it's resulted in a small leak, it may permanently take care of the problem.
A hissing, ticking, or rhythmic "puff, puff" sound when accelerating usually means high-pressure combustion gases are escaping a damaged head gasket. The sound gets louder and faster with more engine load. Pull over safely to prevent catastrophic engine damage, and check for these signs:
You will feel a significant loss of power as the pressure in the combustion chamber will have been lost. Your engine may also overheat if the blown head gasket is causing coolant to leak, which can cause further cracking and irreparable damage to the engine.
A blown head gasket is often called the "kiss of death" for a car engine, but its major symptoms can easily be misdiagnosed. The most common lookalikes are failures in other cooling, exhaust, or engine sealing components.
How to Tell If You Have a Blown Head Gasket
When a head gasket fails, it usually causes engine oil and coolant to mix. As a result, the coolant often takes on a thick, foamy, and milky appearance, closely resembling a chocolate milkshake.
A blown head gasket is almost always caused by engine overheating. Because the gasket seals the engine block and cylinder head, extreme heat causes the metal to warp, crushing the gasket and breaking the seal.
To test for a blown head gasket at home, use a combustion leak test kit (often called a "block tester"). It costs about $25 to $45 and checks for exhaust gases in your cooling system. You can also inspect your oil, check the exhaust, or look for constant bubbles in the coolant reservoir.
When a head gasket blows, engine oil and coolant mix, which fundamentally alters the oil's appearance. It takes on a distinctive milky, frothy, or creamy texture and color, closely resembling a chocolate milkshake, caramel sauce, or mayonnaise.
The spray test can be done simply with some water. Spray water over the suspected vacuum leak area. If you hear it get sucked into the engine, you have a vacuum leak. This test is most effective in identifying larger leaks caused by cracks in the lines that may be difficult to see during a visual inspection.
Symptoms of Failure: When an intake manifold gasket fails, it often leads to symptoms like poor idling, rough running, or a coolant leak. Conversely, a failing head gasket can cause more severe issues, such as overheating, white smoke from the exhaust, or engine misfires.