The Car Engine Workshop

Have you ever opened the bonnet of a car and wondered what was going on in there?

A car engine can look like a big confusing jumble of metal, tubes and wires!


Students have the chance to work it all out! Watch this page to track our discoveries...

Here's our engine:


The engine

The engine is the heart of the car.

Instead of pumping blood it pumps fuel and air.

Its main job is to convert air and fuel into a rotary

motion to drive the wheels of the car.

On the top is the air cleaner.

On the right is the cooling fan at the front of the car.

On the left is the flywheel and clutch plate assembly.


Back view: The flywheel and clutch plate end


Front view: The cooling fan and radiator (missing) end

ThfeFirst we took off the air filter

First we removed the air cleaner:


Next we unbolted the rocker arm cover to view the valve train underneath:


The valve train's only job is that of a traffic cop.

It let's air and fuel in and out of the engine at the

proper time.

It is made up of valves, rocker arm, pushrods,

lifters and the camshaft.

The Distributor

Here we can see 4 pairs of valves which means it is

a 4 cylinder engine.

There is quite a bit of oil in this area so the valves have

valve seals to stop the oil getting into the combustion

chamber in the cylinders underneath.

The Timing Chain


The timing belt links the camshaft to the crankshaft.

It opens and closes the valves in the correct way.

If the timing belt breaks or slips, the crankshaft keeps going

but the camshaft stops spinning and the valves stop moving.

The valves and pistons are so close together that if the valves

stopped moving and the crankshaft kept spinning, the valves

would crash into the piston.

This would result in a BIG problem!

The Distributor

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The distributor's job is to distribute electricity to each spark plug in sequence, one after the other.

Leads from the distributor snake around the engine from the brown distributor cap (left) to the spark plugs (middle).

The leads have been removed to show the spark plugs (right).


The distributor rotor spins inside the cap.

Each time it passes a contact it sends a burst of

electricity to one of the spark plugs.


Here are the 4 contacts in the cap a (you can see only 2).

Each contact is connected to a spark plug.

As the rotor spins it fires each spark plug in sequence.

See how it works here


The Clutch Plate


In a car a flywheel ( the toothed wheel you can see in the photo) is connected

to the engine. The clutch plate in front is connected to the transmission.

When your foot is off the clutch pedal the clutch plate is pressed

(by a very powerful spring) firmly up against the engine flywheel

so they both turn together.

When your foot presses down on the clutch the clutch plate moves away

from the flywheel. The clutch plate stops rotating.

You can now select a gear without damaging the gearbox.

The Clutch bits:

How a clutch works here


The Clutch housing from the front.

The diaphragm springs are in the centre.

The spring helps push the clutch plate

away from the pressure plate when

the clutch is pressed down.


The Pressure Plate

Here's the back of the clutch housing.

You can see the pressure plate.

This pushes against the clutch plate,

which pushes against the flywheel, which

locks the engine to the transmission and

makes them spin at the same speed.


The Clutch Plate and springs.

The brown sections around the edge

are friction pads to make a good

connection with the flywheel.

The springs act like shock absorbers

when the clutch is engaged.


The Alternator


The alternator works with the battery to generate power for the electrical components in the car,

like the interior and exterior lights, and the instrument panel.

Alternators are found near the front of the engine and are driven with belts from the crankshaft.

You can see the alternator and its belts behind the fan blades in the bottom left photo.

There is a drive belt on the front of the alternator from the crankshaft pulley to the alternator pulley.

You can see the grooved pulley that holds the belt (bottom right)

Older units, like this one, have fan blades for cooling on the rotor shaft behind the pulley.


The Camshaft

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The camshaft uses secially shaped lobes called cams that push against the valves to open them

as the camshaft rotates. You can see a cam close-up on the right, It has a pointed shape on one side

of the ring. The points on the cam are facing in different directions along the camshaft. This means that

the valves open and close in sequence at different times. Springs on the valves return them to their closed position.