- Alright, alright, alright, alright, now Bart.
Yeah?
What's cooler than being cool?
Ice Bart.
Oh yeah.
(electronic music)
Hey there cool kids,
today we're talking about something I know a lot about,
being cool. (children cheering)
If you're watching this,
you probably already know how to be cool,
but what about engines, huh?
How can an engine be cool?
Please tell me how to be cool
Shut up, nerd engine, you'll never be cool,
you wear glasses.
Now get out of here.
Ugh, I'm sorry you had to see that folks.
An internal combustion engine is a lot like my inner thighs,
it produces a lot of heat.
You gotta keep engines from overheating
and sometimes you gotta keep them from freezing.
Some people live in places where it freezes, weird.
In that case,
you'd need something to do the opposite of freeze,
some sort of antifreeze.
(man maniacally laughing)
Antifreeze is also referred to as coolant
when it's mixed with water
if you're like me, you may have thought that coolant
referred to an ant that has a bunch of tattoos.
Well, it doesn't.
Coolant is a liquid
that prevents your engine from overheating.
Wait a minute,
the same liquid can keep your engine from overheating
and keep your engine from freezing
and make you go blind if you drink it?
That sounds unpossible, but true.
You could just use water to cool your engine
and it'd do a decent job
but there are more than a few problems
with relying on water.
One, in extreme heat it boils over,
it overheats and damages the engine and two,
in extreme cold, it freezes,
expanding and breaking the engine.
Antifreeze is a chemical mostly consisting
of ethylene glycol
or sometimes the lower toxicity propylene glycol.
When mixed with water it serves to lower the freezing point
and raise the boiling point in the mixture.
It also includes some corrosion inhibitors
that are needed to prevent rust from forming
on the metal parts like water pumps and engine blocks.
When the antifreeze gets brow or rusty in color
that means the inhibitors are broken down
and the antifreeze,
now just like a pet dolphin that ran away,
needs to be replaced.
Antifreeze works because the
freezing and boiling points of liquid
are colligative properties,
meaning they depend on the concentrations of solutes
or dissolved substances in the solution.
A pure solution freezes because the lower temperatures
cause the molecules to slow down
allowing the natural attractive forces between them
to capture and bind them into rigid crystalline structures,
but adding a different kind of molecule to the mix
blocks those attractive forces
and prevents the crystalline structures from forming.
The more solutes that are added,
the lower the temperature needs to be
before the solution can properly freeze.
If you're confused, don't worry,
so am I, all the time, about everything.
Why am I being filmed?
See when water freezes,
it crystallizes and expands like your mom.
When water had something dissolved in it,
the molecules have to work more
to get near each other to crystallize.
That extra work to crystallize drops the freezing point.
That's why road salt works, it dissolves in water
or on contact with snow or ice,
and if it dissolves, it breaks up the crystals
and makes the crystals harder to form,
but salt, even when dissolved in water,
can still be hard enough that when they shoot around
in a closed system like your engine, they could do damage.
Ethylene glycol works great
'cause not only is it water soluble,
it's what we call miscible,
which means it can be mixed with any amount
and still mix evenly.
Antifreeze and water should have a mixture percentage
based on the lowest temperatures
typically seen in your climate.
In most regions, these are 50-50 water-antifreeze mixture
which will provide sufficient protection
from little below freezing to a high of 265 degrees.
In the coldest temperatures,
you could use a mix of 60 to 70% antifreeze.
The color of antifreeze is from a coloring dye.
Not just the chemical used but specific colors
often mean something differently in the chemical makeup.
The main antifreeze colors that you run across
are the tradition green and extended-life yellow
and extended-life pink or orange.
Antifreeze has got a specific color
and that's so if it's leaking, you know what it is.
Now to see how that antifreeze gets around,
let's go inside the engine.
- You wanna go inside of me? - What?
No, shut up nerd engine and get out of here
before I blow you up.
Sorry gang, I gotta take care of that engine
like I took care of Mr. Carburetor
when I found out he stole my kidney.
You think I wouldn't find out, huh?
- Calm down, Bart, we can talk about this.
(thudding) (metal clanking)
Oh, what are you, please, times are tough.
Please, oh.
(thudding)
I'm sorry.
(Carburetor crying)
I'm sorry.
- Coolant flows through a path
that takes it from the water pump
through the passages inside the engine block
where it collects more heat produced by the cylinders.
It then flows up to the cylinder head,
or heads in a V type engine,
where it collects more heat from the combustion chambers,
then it flows out past the thermostat,
if the thermostat's opened up to let it pass,
through the upper radiator hose and into the radiator.
Here the coolant flows through the thin flattened hoses
that make up the core of the radiator
and it's cooled by the air flow across those vents.
The coolant flows out of the radiator,
through the hose and back to the water pump,
by this time cooled off
and ready to go grab more heat from the engine.
A car's water pump's used to send fluid to the engine block.
It's a simple centrifugal pump driven by a belt
connected to the crankshaft of the engine,
and that uses centrifugal force
to send the fluid outside while it spins,
making it drawn in from the center continuously.
The inlet of the pump is located near the center
so the fluid returning from the radiator
hits these pump veins.
Pump veins fling the fluid to the outside of the pump
where it can enter the engine in there,
makes it way through all those passages
in the engine and the cylinders
where it returns to the cylinder head of the engine.
Thermostat's located where the fluid leaves the engine.
The plumbing around the thermostat
sends the fluid back to the pump directly
if the thermostat's closed.
If it's open, the fluid goes through the radiator first
and then back to the pump,
thermostat's regulating the amount of water
that goes through the radiator.
Nowadays a lot of these mechanisms
are controlled by computers
but the secret to the thermostat used to lie
in a small cylinder
located in the engine side of the device.
The cylinder is filled with a wax
that begins to melt at around 180 degrees Fahrenheit.
A rod connected to the valve presses into the wax
and when it melts, it expands a bunch,
pushing the rod out of the cylinder and opening the valve.
That's how turkey thermostats work.
Bing.
Life hack, if you wanna reuse them,
put a rubber band around them
and let it cool off in your fridge
and then you stick it in whatever turkeys you want.
How many turkeys are you cooking?
None, one a year, and you probably did it wrong.
The radiator essentially takes the heat from the coolant
and gives it to the air.
Most modern cars use aluminum radiators.
They're made by brazing thin aluminum fins
to flattened aluminum tubes.
The coolant flows from the inlet to the outlet
through all of these tubes mounted in parallel arrangement.
Fins conduct the heat,
transfer it to the air flowing through the radiator.
Sometimes these tubes got a fin inserted called a turbulator
which is what I'm gonna name my first kid.
The turbulator increases the turbulence of the fluid
flowing through the tubes.
If the fluid flowed evenly,
only the stuff actually touching the tube
would be cooled directly.
When you create that turbulence,
more fluid is getting cooled.
(children cheering) Crazy, you guys are so smart.
This means more heat's extracted
and all the fluid inside the tube is used effectively.
All this talk of fluid in tubes
reminds me of the lab where I was conceived.
Now, the radiator cap itself
actually increases the boiling point of your coolant
by about 45 degrees.
Works the same way a pressure cooker
prevents water from boiling.
The cap is actually a pressure release valve
and on cars it's usually set to about 15 PSI.
The boiling point of water increases
when the water is placed under pressure.
It's got no where to expand and turn into gas.
Water below sea level boils at higher temperature
'cause it's under more pressure from the atmosphere.
When the fluid in the cooling system heats up,
it expands, so the pressure builds.
The cap is the only place where this pressure can escape
so the setting of the spring on the cap determines
the maximum pressure in the cooling system.
When the pressure reaches that point,
it pushes the valve open,
allowing coolant to escape from the cooling system
and keeping the pressure where it should be.
The coolant flows through the overflow tube
into the bottom of the overflow tank.
This arrangement keeps air out of the system,
and when the radiator cools back down,
it creates a vacuum in the cooling system,
pulls open another spring in the loaded valve,
and that sucks water back in
from the bottom of the overflow tank
to replace the water that was expelled.
Used to be you just had a big old fan driven by the engine
cooling all of this off,
but nowadays the cooling fan is controlled externally
to maintain a constant engine temperature.
Some fans are controlled either with a thermostatic switch
by the engine computer
and they turn on when the temperatures of the coolant
gets above a set point,
and turn back off when the temperature drops below.
There's also a separate circuit for the heating system.
This circuit takes fluid from the cylinder head
and passes it through a heater core, then back to the pump.
Heater core, located in the dashboard of your car,
is really a little tiny radiator.
The heater fan blows the air through the heater core
into the passenger compartment of your car
and keeps you warm.
The heater core draws it's coolant from the cylinder head
and returns it to the pump, so it works regardless
if the thermostat's open or closed.
If your car is overheating, you can turn on the heater
and it can pull hot air from the engine compartment
and cool off your engine.
I'm sorry everybody, I can't do this anymore,
I got a confession to make.
It's something I've been hiding
for at least several minutes.
Well, here it goes. (dolphin chirps)
Liquid is not the only way to cool an engine
and I created a human dolphin hybrid in the lab.
Oh, it feels so good to get off my chest.
So yeah, there's liquid cooled engines
and air cooled engines.
Technically, all engines are air cooled
because even water cooled engines use air to cool the water.
Mind-blowing right.
Well, pick your jaws up off the floor and I'm gonna go on.
Air cooled engines have fins extending out
that pull heat away.
Cool air is forced over the fins typically by a fan.
Those air cooled Porsches and VW engines were boxer engines
because they can expose more surface area to the air
to cool 'em off.
The explosions in the chamber
aren't serving to warm up a huge solid engine block,
just their own chambers.
Also, they've got what amounts to essentially a fan
in the engine to pull air through,
and those crazy, distinctive holes in the back
and all around those old Porsches and Bugs and vans,
well they're there to let as much air as possible in
so that it can get around and through the engines.
So, if there's enough air flow, those dang ol' engines,
they're gonna last just about forever.
These days air cooled engines mostly show up in motorcycles,
all-terrain vehicles, riding lawn mowers and aircraft.
Personally I got an air cooled engine
in my all-terrain riding law mower helicopter cycle.
Join us n...
Who are you?
- It's me, Bart, nerd engine.
Turns out I was just overheating.
I put some coolant up inside me and boom,
my glasses fell off and now I'm cool.
- Boy, I'll say you are.
You're the coolest engine I've ever seen.
Say nerd engine.
- Yes, Bart.
- Do you maybe wanna go to prom with me?
- I thought you'd never ask.
- Woo-hoo-hoo!
Cooling an engine!
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