Engine Work & Repair

Car Engine Overview

Basic Engine Operation

The engine powers your vehicle by changing fuel into energy. In other words, it changes chemical energy into mechanical energy. The engine requires fuel and clean air flow, coolant and water, electricity for ignition and oil for lubrication.

The engine consists of hollow cylinders called combustion chambers and pistons that move up and down inside. This is where the basic operation starts. Fuel and air combust inside the chambers, which causes the piston to move. Cars usually have 4, 6, or 8 of these cylinders which can be arranged in various positions.

Parts of an Engine and What They Do

The engine has thousands of parts working together. This is why you should use an experienced auto mechanic with proper training. All of these parts come together in a feet of mechanical, chemical, electrical and (now) computer engineering. Customers should definitely keep this in mind when considering how much time mechanics take when they inspect your engine. Here we provided a list of engine parts to keep familiar with, so that you can be informed and understand your engine diagnosis:

1. The Engine Block (or Cylinder Block)

The engine block contains the structure of the cylinders and other passageways. It is also called a cylinder block because it contains the cylindrical holes where the pistons move up and down. This is also where the crankshaft spins, and in some engines holds the camshaft. In modern vehicles, the engine block is made from aluminum alloy for its capability to transmit heat to the cooling system. Common problems with the engine block include a coolant leakage, a worn cylinder, and a porous engine block caused by contaminated metal during its manufacture.

2. Combustion Chamber and Piston.

The combustion chamber is where the energy for your motor to run is created. Air, pressure, fuel and electricity come together to form an explosion that moves the piston up and down. The combustion chamber consists of the cylinder head at the top, the cylinder round the sides and the piston at the floor. The piston attaches to the crankshaft via the connecting rod. When is moves up and down, it spins the crankshaft. Grooves cast around the pistons are called piston rings. Compression rings at the top create a seal against the walls of the combustion chamber. Oil rings prevent oil from seeping into the combustion chamber. 

3. Cylinder Head, Fuel Injectors & Sparkplugs.

The cylinder head is the sealed cap of the combustion chamber. It also holds the intake and outtake valves, the sparkplugs and fuel injectors. The fuel injectors spray gasoline (or diesel) into the engine. There is one fuel injector per cylinder mounted on the cylinder head. The sparkplug converts electrical energy into chemical energy. After fuel is injected in the combustion chamber, the sparkplug ignites the air and fuel mixture to create an explosion. This explosion forces the pistons up and down, converting the chemical energy into mechanical energy.

4. Camshaft and Crankshaft

The crankshaft rotates according to the output of mechanical energy from the combustion engine. It rotates by the connecting rod of the piston. The Camshaft on the other hand is located above the engine. Its job is to open and close valves that fill the engine with the air and fuel mixture needed for combustion. It is powered by the crankshaft and timing belt. On problem that can occur with modern vehicles is the failure of the crankshaft position sensor. This sensor monitors the rotational speed and position of the crankshaft. If the sensors fail, the engine can misfire and vibrate. 

5. Timing System

With thousands of moving parts, the timing is essential for an engine to work properly and efficiently. First of all, the fuel/air mixture should fire right as the piston reaches the top dead center (TDC) during its rotation. In the most basic explanation, the crankshaft turns the timing belt, which in turn powers the camshaft which opens and closes fuel and air valves at a synchronized pace. With computer systems, newer cars use an electronic timing system which times the spark more precisely. The timing is monitored by sensors, too. So, if your engine is misfiring or failing, your car can give you warnings and sometimes shut down automatically in order to avoid further damage to the engine. 

6. Valvetrain and Valves

The valvetrain or valve train includes all of the parts of the engine that are needed to open and close the fuel and exhaust valves. The camshaft is the most important part of this assembly. Depending on the type of engine, the valvtrain can inlcude one or multiple camshafts. Some cars have one camshaft, some have multiple, and some have one camshaft for exhaust and one for fuel. Cam lobes are located on the camshaft, and open and close the intake and exhaust valves depending on the location of the piston. The cam follower is located on tope of the valve. The cam lobe pushed on the cam follower when it rotates. Then, the cam follower transitions the rotary motion to an up-and-down motion the opens and closes the valve. 

7. Rocker Arms

A rocker arm is a cooler way to say cam follower. These convert the rotational energy into linear energy. The engine timing relies, in part, on the size and shape of the rocker arms which determine how long the intake and exhaust valves stay open. 

8. Pushrods / Lifters

Pushrods and lifters are also part of the valvetrain. The lifter connects to the camshaft, and the pushrod to the lifter. When the camshaft rotates, the pushrod pushes up on the rocker arms, which teeter-totters the the rocker arm and pushes down the valves.

We hope this gives you more familiarity with engine work. If your engine is vibrating, misfiring or your check engine light is on, call us at 314-849-2900! Sant Automotive is happy to help! For more information, check out this video from our parter BG Products.