Driver Guide To A Car Engine Operation

Your engine is one of the most complex assemblies under the hood (second only to the transmission). It is filled with moving parts that work together seamlessly to propel your vehicle down the road. But few people are familiar with the process that makes this possible.

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Below, we’ll take you on a brief tour of your car’s engine. You’ll learn about the components that play key roles in its operation. We’ll describe what these parts do so you’ll understand how they contribute to the performance of the assembly. You’ll also begin to appreciate why certain problems surface as the components wear down over time.

Major Components Of Your Engine

The size and power of the assembly is dictated by the number of pistons. Small passenger vehicles may only have four. Sedans may have six, and larger automobiles and performance vehicles often have eight. Some trucks come with more. Each piston is contained within a cylinder. The top section of the cylinder is called the combustion chamber. The piston rises up and down according to a precisely-timed 4-stroke combustion cycle (described in more detail in the following section).

Each of the engine’s pistons are attached to a shared component called the crankshaft. As the pistons rise and fall within their respective cylinders, the crankshaft turns on its axis. It rotation moves your vehicle.

Atop each cylinder is found an intake valve and an exhaust. These open and close to help regulate the flow of fuel, air, and exhaust. The valves are connected to camshafts, which, in turn, are connected to rocker arms, lifters, and other parts. These comprise your car’s valvetrain.

Together, the pistons, crankshaft, and valvetrain control the timing of your engine’s 4-stroke combustion cycle. This cycle occurs inside each cylinder, and is the most important task for which your engine was designed.

The 4-Stroke Combustion Cycle

Recall that fuel enters the cylinders through the intake valves. Also, recall that the up-and-down movement of the pistons causes the crankshaft to rotate, which moves your car. What follows is a step-by-step description of this process. There are four distinct strokes: intake, compression, power, and exhaust.

The intake stroke occurs when a camshaft forces the intake valve open. As it opens, the piston descends within the cylinder. Air and fuel fill the chamber, after which the intake valve closes.

The compression stroke begins when the piston starts to rise from the bottom of the cylinder. With the intake valve sealed, the air-fuel mixture in the combustion chamber starts to compress. By the time the piston reaches the top of its path, the mixture will have been compressed to approximately 10 percent of its beginning volume.

During the power stroke, a spark plug at the top of the cylinder ignites the compressed air-fuel mixture. This produces a rapid expansion of gases. The vapors push the piston downward in the cylinder, causing the crankshaft to rotate.

The exhaust stroke is the last stroke in the cycle. At this point, the piston is at the bottom of the cylinder. The exhaust valve opens, and the piston begins its ascent again. This pushes the vapors in the combustion chamber out of the cylinder via the open valve. Once the gases have been expelled from the chamber, the exhaust valve closes, and the combustion cycle begins anew.

How To Extend Your Engine’s Life

The components mentioned thus far (pistons, valves, camshafts, crankshaft, etc.) will eventually wear out. Under normal driving conditions, a new engine can be expected to last 100,000 miles or more before it needs to be overhauled or replaced. You can prolong its life by keeping the oil level replenished, and changing the oil according to the service interval recommended by your owner’s manual.

Also, make sure to have the timing belt replaced every 60,000 miles. If it breaks while your engine is in operation, it can cause expensive damage to the valves and pistons.

Being familiar with your engine and how it operates is useful for troubleshooting sporadic issues. While repairing engine problems may be beyond your skill and experience, knowing what caused the problems in the first place can prove invaluable.

Things That Can Go Wrong With Your Vehicle’s Clutch

It may surprise you to know that your car has at least one clutch, even if your transmission is an automatic. In fact, your vehicle might have several of them. A clutch is a relatively simple component that connects two rotating shafts and allows them to spin at the same rate. It can also disconnect the two shafts, allowing them to spin at different rates.

For example, consider the tires on your car. They’re connected to the engine and rely upon it for propulsion. The engine is constantly spinning, even if you’re sitting at a red traffic light. Because your tires are not spinning constantly, a clutch is needed to reconnect the tires and engine when the traffic light turns green.

Unfortunately, clutches are like all auto parts: they can fail from normal wear and tear. Below, I’ll describe a few problems that you might eventually experience with your car’s clutch.

The Slip

When your vehicle’s clutch is engaged, it is supposed to slip in order to prevent jerking. This is the case whether you’re starting from a dead stop or changing gears. Normally, when you remove your foot from the clutch pedal, the component should establish a smooth connection between the engine and the transmission. If you notice excess slippage, there’s a problem. A little leads to a lot because the heat generated from the friction makes it even more difficult for the clutch to grip its position. So, it slips even more.

The Jerk

Technically, this problem is called “chatter.” It’s characterized by a lurching or jerking motion when you engage the clutch. The most common cause is oil on the linings. However, there are several factors that can contribute, including a warped flywheel, misaligned chassis, and even a damaged CV joint.

Grinding Or Growling

When the bearings are severely worn, vibrations inside the clutch actuator can produce squealing, grinding, or growling noises. Like chatter, a lot of factors might be involved. For example, the bearing retainer might be damaged, the release bearing may have failed, or the disc may have been installed poorly. Different causes lead to different noises. A squeal may be caused by a malfunctioning pilot bearing while a growl can be caused by a transmission bearing.

The Stubborn Link

If you press down on the clutch pedal, but the clutch refuses to disconnect, you’ll be unable to shift into gear. You’ll probably hear a loud grinding noise and your engine might stall. This can happen if the release cable breaks, if the hydraulic line has air in it, or the clutch disc has become warped or bent. It can also be caused by a leaking master clutch cylinder.

If your car’s clutch fails, you should have a mechanic replace it as opposed to doing the work yourself; the job is usually labor-intensive. Make sure the replacement that he installs meets OEM specs. Your clutch is one of those systems with which you do not want to take chances.

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