| Your vehicle's head gasket (HG) is sandwiched | | | | There are a few ways in which a bad HG installation |
| between the cylinder head and engine block. The part | | | | can cause problems down the road. One of the most |
| serves multiple purposes. First, it prevents coolant | | | | prevalent issues involves the head bolts. These bolts |
| from seeping into each cylinder's bore. Second, it | | | | hold the gasket securely to the engine block. If |
| helps maintain pressure within the engine by sealing | | | | they're tightened down with the wrong torque, they |
| off the combustion chambers. The operation and | | | | will create seal problems. |
| performance of your car are heavily dependent on | | | | Another issue involves the surface of the block or |
| the HG's ability to keep the seal intact and free from | | | | cylinder head. If either surface is less than smooth, |
| leaks. | | | | the rubbing between them will accelerate the |
| When the head gasket fails, it must be replaced. | | | | gasket's deterioration and eventual failure. |
| Unfortunately, the job is expensive - the price can | | | | Occasionally, head gasket failure is due to the type |
| climb past $1,000. The part itself is relatively | | | | of sealer used upon it. If the HG is made from a |
| inexpensive; a high-quality head gasket typically costs | | | | composite (e.g. graphite), the wrong sealer can cause |
| less than $70. The reason replacing it is so costly is | | | | a chemical reaction. This reaction can degrade the |
| due to its location. The mechanic needs to remove | | | | gasket's integrity. |
| the engine head in order to get to it. | | | | Stress From Engine Problems |
| Below, you'll discover the main reasons the HG fails. | | | | As I mentioned earlier, there are factors that impact |
| Some you can avoid while others may be | | | | your vehicle's head gasket that you can influence. |
| inescapable. | | | | These involve problems with your engine. The most |
| Stress Between Disparate Metals | | | | common engine-related issue that leads to gasket |
| Your car's cylinder head and engine block are made | | | | failure is detonation (also known as spark knock). |
| from different metals. The heads are usually | | | | This occurs when the air-fuel mixture within a |
| comprised of aluminum. The block is made from cast | | | | cylinder's combustion chamber is poorly calibrated. It |
| iron. One of the reasons cylinder heads are made | | | | can happen due to a malfunctioning exhaust gas |
| from aluminum is because the metal is lighter than | | | | recirculation (EGR) valve, bad (i.e. cheap) fuel, and |
| iron. The problem is, aluminum has a higher thermal | | | | carbon buildup. These circumstances can cause the |
| expansion rate. When the temperature around your | | | | mixture inside the chamber to ignite erratically, which |
| engine rises (as it does during operation), the | | | | places stress on the gasket. |
| aluminum expands much more quickly than the block's | | | | Another engine-related problem is overheating |
| iron. | | | | (though this is a rarer cause of HG failure than spark |
| This places stress on the HG. The head and block rub | | | | knock). Your engine is already operating at high |
| against each other because they are expanding at | | | | temperatures. When it overheats, the temperature |
| different rates. Even though the gasket sitting | | | | rises dramatically. While the HG is designed to |
| between them is normally designed with steel or | | | | withstand heat, the significant rise can cause it to |
| copper, the constant rubbing over thousands of miles | | | | deteriorate. |
| gradually tears it apart. | | | | There's obviously very little you can do about the |
| Many of today's vehicles are equipped with HGs | | | | type of metals that comprise your car's engine block |
| made of graphite. This material is more capable of | | | | and cylinder head. And you're unlikely to have much |
| withstanding the stress caused by the varying | | | | say over the HG's installation. But you can influence |
| expansion rates of the cylinder head and engine | | | | the long-term health of your engine and thereby, help |
| block. But they can still break down over time. | | | | protect the integrity of your vehicle's head gasket. |
| Bad Installation | | | | |