For many of us, the moment we really start to care about what exactly is happening under the hood of the car is also the moment when something has gone wrong. The dreaded “check engine” light can bring visions of expensive repairs or thoughts of having to replace Old Faithful. Oh, and smoke billowing out from that general area is not such a good sign. So what exactly happens inside an engine, and what does all the automotive jargon mean when stickers flaunt an “inline 6 engine?” Take a look.
Today’s vehicles use internal combustion engines (such as diesel engines or gas turbine engines), which are vastly different from external combustion engines – think steam boats and coal-burning trains. In gas turbine engines, pressurized gas which the engine produces spins the turbine, like in free jets. In nearly every car or truck is a four-stroke reciprocating internal combustion engine. What a mouthful! Let’s break that down.
In an internal combustion engine, the combustion (the gas burning process) happens within the working cylinders. The four-stroke cycle includes four steps: 1) Intake stroke- where the gas and air fill the cylinder 2) The compression stroke- pressure builds up 3) Combustion stroke- the spark plug ignites the gas, causing an explosion to drive down the piston, and finally 4) Exhaust stroke- as it sounds, this allows the exhaust to exit through the tailpipe. To keep the car moving, the steps continue to repeat.
Different engines, such as inline, V, or flat, refer to the layout of these cylinders. Inside each cylinder is a piston which moves up and down, and those are fun by the crankshaft, which rotates to allow for the up-down motion. A connecting rod, as it sounds, connects the pistons to the crankshaft. Valves control intake and exhaustion. Finally, the sump contains oil and surrounds the crankshaft.
With this basic knowledge, things seem a little less overwhelming when the mechanic is explaining what went wrong and what needs to be fixed on your classic car.