Head gaskets are metal plates sandwiched between the engine block and cylinder heads in traditional car engines. They are used to create a complete seal between the two parts to prevent leakage in or out of the combustion chamber, which also helps provide maximum compression for the most power and efficiency possible. If the part malfunctions or breaks, it can create other problems and damage the engine.
What damages a gasket?
Head gaskets can be damaged by a variety of different factors, but an overheated engine is the most common cause. The rise in temperatures creates thermal expansion between the cylinder heads and the engine block, which puts pressure on the gasket and can crack it. This is known as a blown head gasket. The material of a gasket may not be strong enough to handle the constant heating and cooling, meaning it will fail sooner than a more sustainable part. Ignition misfires and other engine issues can place added strain on a gasket and cause unnecessary damage. An incorrectly installed gasket is also prone to failing.
What happens when the gasket breaks?
A damaged head gasket will result in a loss of compression. This can lead to a drop in performance and fuel efficiency and you may notice the engine is running roughly. A blown gasket also means the seal between the engine block and cylinder head is broken and you may experience a coolant leak. Check the coolant level and inspect the oil for signs of coolant in the oil reservoir. Bear in mind a mixture of these fluids is not necessarily indicative of a gasket issue, as coolant and oil can be mixed through other outlets. If you notice white smoke with a sweet odor coming from your exhaust pipe, this is also a clear indicator the head gasket is blown.
How do you know for sure if the gasket is the problem?
If you suspect the head gasket is blown and have noted the aforementioned warning signs, you can check the engine's compression using a pressure gauge. Compare the readings with the expected compression ratio for your particular make and model. This information can be found in the owner's manual.
When performing this test, be sure the engine is warm for ideal readings. You should also measure the compression a few times for each cylinder to ensure the gauge is providing accurate readings. You should get the same readout every time. When you test a cylinder, you will need to remove the spark plug from that particular one, but leave the rest in.
Can a blown gasket be repaired?
When you catch a leaky gasket early, you may be able to seal the leak with a special sealing material found at auto parts stores. However, this is temporary and will only delay the need to replace the head gasket. Once it is completely blown, you have no choice but to replace the part to get your car working again.
Whether the head gasket is leaking a little bit or has blown completely, it is important to address the issue as soon as possible. Ignoring this issue will only result in more extensive damage to the engine. Coolant leaks will cause it to overheat, and if the coolant mixes with the oil, it can cause other mechanical problems. Addressing the problem right away will save you money and aggravation.