CARS.COM — Your car’s head gasket is an important part of the engine. It seals the cylinder head to the engine block. The cylinder head houses the engine valves while the engine block contains the crankshaft and pistons. Over time, head gaskets can start to leak. These leaks vary in terms of severity, and while a minor leak may simply increase oil or coolant consumption, a more severe leak or blown head gasket can cause complete loss of compression. It can also cause your cooling system to fail and make your car’s engine overheat.
Related: Head Gasket: What You Need to Know
While head gasket replacement is not classified as routine maintenance, there are instances in which the gasket may require replacement. If you think you may need to replace your head gasket, it’s best to talk to a mechanic.
Signs You Have a Blown Head Gasket
There are several signs that could indicate that your head gasket is blown. These warning signs may point you in the right direction, but you will need to have a mechanic at an auto repair shop run your car through a compression test to accurately check the condition and integrity of the head gasket and determine whether you need to replace it.
Coolant consumption: The cylinder head of a modern car has dozens of coolant passages. These passages are a vital part of the cooling system because they allow coolant — or antifreeze — to flow through and remove excess heat. When in good condition, the head gasket seals the passages to prevent coolant from escaping into the engine’s combustion chambers. If the head gasket is damaged, however, it may let coolant leak into the cylinder. If this happens, your engine will start consuming coolant.
Take a look at your exhaust pipe while your car is running. If there is water dripping from the exhaust or excess steam, it could indicate that a blown head gasket. Pay attention to your vehicle’s gauges while driving, too. If your car is running too hot, a blown head gasket could be causing problems with your cooling system and preventing your antifreeze from doing its job.
Oil consumption: If your car has bluish-white exhaust and idles roughly, it may be consuming too much oil. Modern cylinder heads have just as many oil passages as coolant passages. These passages are cast into the cylinder head to transport oil to and from the valve train. The head gasket keeps the passages sealed as oil travels between the cylinder head and the engine block. If your car is burning too much oil, you may have a leak in the head gasket that is preventing it from properly sealing the passages.
Mixing of oil and coolant: A blown head gasket can allow coolant and oil to mix. When coolant from the cooling system mixes into the oil in the engine block, it is detrimental to the oil’s lubricating properties. It can cause significant damage to the engine bearings, cylinders, pistons and other engine components. Check your dipstick. If the oil is brown or bubbly or has any traces of water or other inconsistencies, it could be a sign of major head gasket problems. Stop driving your vehicle, and have the engine inspected right away.
How to Replace a Head Gasket
Head gasket failure is a serious problem that needs to be addressed right away. Unfortunately, head gasket replacement is a major engine repair, and in most cases, it is best to give your mechanic a call when you need to have this type of time-consuming work done. The most difficult part of the project is accessing the gasket; to do so, you have to remove a large set of engine components. The exact process varies from one vehicle to another, so take a look at your owner’s manual or a service manual before even attempting to get started. Even if you’ve done a head gasket replacement in a Honda Civic, the process may be completely different for a Ford F-150 or a Toyota Camry. Make sure you know exactly what you are getting into before you start tearing your engine apart.
Once you’ve accessed the gasket, you’ll need to use a wrench to remove the head bolts from the cylinder. Next, you need to remove the old gasket using a pry bar. Gently clean the surface of the heads underneath where the old gasket was located. This ensures a strong seal for the new gasket.
Before you replace the gasket with a new one, visually inspect your heads. Look for signs of damage, wear and tear, and other problems. If everything looks like it should, securely place the new gasket on the head to ensure a tight seal. If there is a gap, you may need to use a head gasket sealer. Before replacing the head bolts, double-check that there are no gaps between the head and the new head gasket. Check the torque specs to ensure that you tighten the cylinder head bolts to the correct tightness. After you replace the gasket and secure the head bolts, put the rest of the engine back together exactly how you took it apart. If done correctly, the replacement head gasket should have your vehicle running like new again.
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