The gasket and its importance
What is a gasket?
Defining a gasket is not limited to its outlook, the material a gasket is made of or the exact function it is meant to perform in every engine also contributes to how to define or describe it. This, therefore, means that the gasket has different definitions, and each applies to the engine type. Almost in every aspect of work done, there are intricacies, these intricacies are in many cases, essential to the functionality of such work.
The need for order and a specialty brings the meaning and function of the gasket into full view. Ordinarily, a gasket is a material or component that lies between two other components in order to ensure the smooth running of the two other components. We can deduce that a gasket is more or less a wall or bridge as the case may be.
The need for a gasket is, however, totally dependent on the type of engine into which it is built. Gaskets are flexible and mostly flat in appearance. Like ligaments in the body that connects the bones and joints, the gasket albeit very small is of limitless importance to the engine. In fact, the engine can not function without the gasket. In the making of a gasket, special attention must be made to the quality of every material used.
The choosing of the right material for each gasket is a tough job and one that must be done with precision. This is because the effectiveness of the gasket depends entirely on the yielding and deformation quality of such a gasket that must have been considered in the manufacturing process.
Another consideration for the production of a gasket is the conditions in which such gasket will be put to use. The effect of chemicals and gas on the materials should be adequately addressed.
The usage of gaskets is however very important to the working of car engines. Modern vehicles are commonly manufactured with an engine block and a cylinder head bolted on top, which makes a head gasket an important part of the engine A head gasket is a gasket that sits between the engine block and cylinder head in an internal combustion engine.
It is made to seal the cylinders to ensure maximum compression and avoid of coolant or engine oil leaking into the cylinders, therefore, it is the most critical sealing application in any engine, and, as part of the combustion chamber, it shares the same strength as other combustion chamber components. In the engine block are pistons that travel up and down in cylinder bores.
The pistons are connected to rods, which in turn are connected to a spinning crankshaft from which the vehicle takes its power. Bolted to the top of the engine is the cylinder head. Inside the cylinder head are valves that open and close to let air and fuel into the cylinders and expel the spent exhaust gas.
The head gasket is compressed between the engine block and the cylinder head. The head gasket seals in the internal combustion process and also keeps coolant and oil from mixing together as the two fluids travel from the engine block to the cylinder head. Head gaskets themselves are not very expensive. What ends up costing so much is getting to it. Head gasket repairs mean undertaking the major operation of removing an engine's head.
Types of Gaskets
As said earlier, there are different types of gaskets and these are categorized based on a number of options such as the material they are made of as well as the industry into which they fit perfectly. A few of these are discussed below.
1. Sheet gaskets: These types of gaskets are those punched out of flat surfaces. Often filed before being used, they are a very reliable gasket for sealing off different ends in an engine. These gaskets are mostly made from rubber. Although they can also be made from other materials. Sheet gaskets are cheap to get, and they last for a great while.
2. Spiral wound gaskets: For better durability, spiral wound gaskets offer more. The gasket is made by bringing together steel and filler. While the former provides much-needed strength, the latter works as a sealant for the gasket. This proves to be a successful mechanical appliance as it can be used for different industrial engines.
3. Pipe gasket: These gaskets made from different types of materials like rubber and asbestos are further subdivided into two types.
i. Full faced gasket: This type of gasket is perforated to allow the passage of bolts. The whole flange is covered by this type of sealant.
ii. IBC (Inner Bolt Circle): As the name suggests, the Inner Bolt Circle has gaskets that are placed in the space of the bolts as just a ring that both perform the normal function of a gasket as well as support the bolt. They are also regarded as raised face gasket.
4. Manway gaskets: These are multipurpose gaskets that are mostly used in closed vessels. They can be used in a wide range of engines and are very durable.
5. Asbestos gasket: This type of gasket is cheap, can withstand pressure and heat and chemical effects. The properties of asbestos help to make it worthwhile to be used in the making of gaskets. They are usually long and shredded into tiny bits. They, however, can cause health problems that mostly arise from inhaling them. Lung problems and cancer are also likely to occur from using and inhaling asbestos gaskets.
6. Non-asbestos gasket: These are more expensive than the asbestos gaskets, albeit more health friendly. The major material used for non-asbestos gaskets includes rubber and graphite.
Causes of gasket failure
Like every component of the engine, the failure of the gasket is not unexpected. It must be well understood that when the gasket fails, the whole engine will cease functioning. The failure of the gasket is, however, one that does not occur frequently, yet this frequency depends on how fitting the gasket is for the engine in which it is used. That said, a head gasket can fail for a number of reasons, none of them good. Few of these reasons are highlighted below:
Engine overheating: This is the most common cause of gasket failure. When the metal of the engine block and head expands beyond limits during overheating, it will directly affect the gasket. The expansion can pinch the head gasket to the point where it will fail or break. Every gasket is made to endure heat until a certain degree. The elastic limit or pressure limit of the gasket, when exceeded, will cause such a gasket to fail.
Pre-ignition and detonation: The next major causes of head gasket failure are engine pre-ignition or detonation. The crux of these two conditions is out-of-time combustion occurring in the cylinders. Internal combustion is supposed to happen with both valves closed and with the piston at the top of its power stroke. Out-of-time combustion puts extra strain on the valves, pistons and head gasket. Ironically, engine overheating could increase the likelihood of pre-ignition and detonation.
The sound of an engine pinging or knocking is the insidious sound of damage. Every operator of an engine regardless of the industry should be sensitive to the sound being emitted from the engine in order to salvage the failure of such an engine or to reduce the potential extent of the damage.
Replacing a head gasket
Head gasket replacement is not a job for the average do-it-yourselfer. While a head gasket expiring due to old age is rare, it usually means everything else is worn out to the point of replacement as well. Cracking the head off the engine and peering inside may reveal that everything else got fully cooked, too. The best way to prevent head gasket failure is to keep the cooling system in top working order and make sure the engine is in tune and running correctly. The failure of a cheap thermostat and coolant hose can cause much more money in fixing engine damage in a hurry.
How-to tips
These are a few general tips for changing a head gasket. For vehicle-specific head gasket replacement procedures, always consult a service manual.
Getting down to the head gasket can be a tough process. Always mark and index everything before removal. In this case, it was easier to remove the exhaust manifold, head and intake as a unit. A service manual is the first and most important tool in the toolbox.
Check the head and block for flatness. A machined straight edge across the surface and feeler gauge will reveal all. The service manual will provide specifications. Blocks or heads out of specification must be sent out to the mechanic and be repaired. The mechanic will also be able to check for cracks.
Prepare the surface. Never use anything that will remove metal. Be careful not to scratch the deck of the block or mounting surface of the head. While it may seem like a good idea to use a scrubber pad connected to a power tool, the surface irregularities created can cause sealing problems down the road.
Chase the head bolt or stud holes with a tap or thread chaser to remove any crud and prepare the threads. Use compressed air to blow out any stragglers. Correct head bolt torque is of the utmost importance. Any interference can throw off the torque readings. Pre-it the head gasket in the correct orientation. Never use sealant unless specifically required by the manufacturer. Head gaskets that require sealant will usually come so equipped. The service manual will outline sealant locations and requirements.
Correct bolt tightening sequence and torque is key to proper head gasket sealing. Use new bolts if required. Coat head bolt threads with some engine oil before installing.
