If there's one light on your car's instrument panel you should never, ever ignore,
it's this one:
the oil pressure warning light.
It usually looks like a little oiling can.
And if that light comes on while you're driving,
that means you should pull over and shut off the engine as soon as you can possibly do so safely
and then call a tow truck.
And I'm not kidding.
If that light comes on,
your engine may be mere minutes away from self-destruction.
And so continuing to drive is a very risky choice to make.
Now, if you're wondering why exactly the engine could destroy itself when that light comes on,
that's the point of this video.
Today we're going to explore the mechanical basics of the internal combustion engine,
with a particular focus on its lubrication system and why it's required to keep the engine alive.
There's a lot of stuff going on inside one of these contraptions, and by the time we're done here
there's a good chance you'll think it's a miracle we've managed to make these things as reliable as they usually are.
Now, if you're a gearhead or even just gearhead-adjacent,
there's probably not much you're going to learn here.
But if you don't really know that much about engines and how they work,
and really how they keep themselves working,
well I think you'll find this video to be quite informative.
Before we really dive in, though,
there's something you should know about the rest of the lights on your car's instrument cluster.
And that's something is the rest of them!
Because they all mean very important things and are designed to help you.
They're even color coded to convey their urgency and meaning.
Red lights are bad and need your attention now
because they indicate an unsafe condition where something is majorly wrong.
Yellow lights are warnings which can vary in severity
but probably don't need your immediate attention.
And other colors are usually reserved for simple information,
like the blue light that warns you your high beams are on
so please shut them off unless you're in the middle of the country — that's not for use with other cars around!
Or the white or green status indicators for the cruise control system.
If you want to know just what exactly all those lights mean,
your car will have an owner's manual somewhere
and there's going to be a handy little section which explains each and every one of them and why they might light up.
I'd highly encourage looking at that section of the manual
and committing those details to memory.
But anyway, this is a video about the engine and how it works.
So let's dig into it.
First, though, if you'll indulge me,
here's a brief overview of how electric cars work:
[two toots of the drill]
But bigger.
And now let's take a look at this Renault-Nissan MR-18DE,
the engine which powers the venerable Nissan Cube.
Let me just, uh, take it apart real quick.
Okay,
this is the engine block.
It's really nothing more than an intricately cast and machined hunk of metal,
but it's the heart of the engine and contains the cylinders.
In this case, there are four of them,
and they're all arranged in a straight line,
which makes this an inline four cylinder engine.
Probably the most common type of engine out there in cars.
Not all four cylinder engines are alike, of course;
these cylinders come in many different sizes, so some are more powerful than others,
and they're not always arranged in a line.
We'll talk more about that later, though.
Oh also sometimes there aren't cylinders at all!
But that's mainly a Mazda thing they only sometimes do
because rotary engines are equal parts cool and terrible.
But they're committed to them!
Sometimes - for special occasions.
Anyway, the cylinders are each a combustion chamber.
The idea is to fill these cylinders with a mixture of air and fuel,
and then ignite that mixture so it...
expands very rapidly.
I would say that mixture explodes,
but it's not technically an explosion.
What's really happening is that the carbon dioxide
and water vapor that are produced in the combustion process
have a much larger volume than the fuel and air did before it ignited,
and that rapid expansion of hot gases inside the combustion chamber
can be harnessed and turned into mechanical work.
And to do that we use pistons.
Each cylinder gets a piston just like this inserted from the bottom,
and these pistons are able to slide up and down inside the cylinders.
During a combustion event, as the mixture of hot gases inside the cylinder rapidly expands
these pistons are forced downward into the engine block.
And that's how we convert the chemical energy in the fuel into mechanical energy.
Now, the goal of this engine is to spin the wheels of a car.
So ultimately the engine produces rotational movement.
And since the pistons move up and down inside the cylinders,
we're going to need a mechanism to translate their up and down motion into a spinning motion.
If you noticed the weird stick thing with a ring on the end that each piston has,
well, this is the connecting rod and it's there to connect the pistons
to this thing.
This is the crankshaft, and it is the thing that spins.
The tachometer, the gauge which tells you engine RPM,
is telling you how quickly this literal thing is spinning inside the engine block.
Now we're going to look at this closely in a moment to see how the pistons make it spin.
But first I want to point out that the crankshaft sticks out from the block on both sides.
That is how we actually make this spinning crankshaft
do useful things for us.
Bolted to one side of it
is this large rusty wheel with teeth on its edges.
This is what's known as a flexplate.
The teeth on its circumference are there for the electric starter motor to engage with,
and turn the crankshaft inside the engine in order to start it from a stop.
But the rest of this connects the engine to the transmission
so that once the engine is running
the spinning crankshaft can spin the wheels of the car.
Technical note: if you were expecting me to call this a flywheel,
well, this is not a flywheel.
It's a flexplate.
What's the difference?
Well, flywheels are used with manual transmissions,
while flexplates are used with automatic transmissions.
In a car with an automatic, which is what this engine was taken from,
the flexplate gets fastened to the transmission's torque converter,
and the engine and transmission are permanently coupled together.
But flywheels are completely different.
They're used with manual transmissions
and are not really fastened to the transmission at all,
since in a stick shift the engine and transmission are mated with a clutch under the driver's control.
The clutch sort of presses up against the flywheel
when engaged to connect the transmission to the engine,
and it moves away from the flywheel when disengaged to separate them.
And because of this, flywheels have a smooth surface
on the outer side which the clutch pushes against.
It's also quite a lot thicker and heavier than a flexplate
to give the crankshaft more rotational momentum:
helpful when getting the car moving from a stop.
This Nissan Cube has a manual transmission,
so its engine has a flywheel attached to the crankshaft and not a flexplate,
but everything else is identical.
Now, while moving the car is the main thing the spinning crankshaft has to do,
it also has to do things like generate electricity to keep the car's battery charged.
And that needs to happen whether the wheels are moving or not.
Which is why the other end of the crankshaft also sticks out from the engine block.
But on this side, all we have attached to it is the small pulley.
This is the crank pulley
and it provides power for engine accessories such as the alternator,
air conditioning compressor and water pump via a drive belt.
The pulley simply bolts on to the end of the crankshaft here...
with this large bolt.
Oh, and like in many engines,
that pulley has some rubber like material in there
to allow it to function as a harmonic balancer.
But that's not important right now.
What is important right now
is how the uppy downy pistons actually make the spinny spinny crankshaft spin in the first place.
To explain, I want you to focus on these very shiny
and perfectly circular surfaces you can find on the crankshaft.
These are bearings,
just plain bearings.
which is a dad joke because they are literally called plain bearings.
[voiceover] Oooookay editor me popping in
with some notes on terminology.
I made the mistake when writing this script
of letting a technical definition supersede
the common language most people use.
These are indeed plain bearings,
but they belong to a subset of plain bearing known as journal bearings.
And the circular, shiny things we're looking at on the crankshaft
are usually referred to as the journals.
But here's the thing.
Journal is simply another word for shaft.
All these things are is a polished, circular shaft
which spins inside of a stationary circle,
which wraps around and holds on to the shaft.
Once put together, it's really just two concentric circles
where one spins and the other doesn't.
And both the spinning journal and its stationary
holder are a bearing surface,
which is what I wanted to highlight in this video.
The interface between those two bearing surfaces
is what really matters to the point here.
And from either one's individual perspective,
the other part is what's spinning.
And so that's why I ultimately chose to refer to these as bearings.
But I understand a lot of people will be very annoyed by that choice.
And so... sorry about that.
They consist of that smooth,
shiny part in the center of the crankshaft
and a thin bushing which surrounds it.
You can see half of the bushings here in the block.
[voiceover] Oh, hi. Me again.
See, this right here explains the problem.
This is literally the bearing.
This is the bearing surface.
But technically it is a bushing.
However, when people rebuild engines,
they're going to refer to these things
as the bearing because it's the bearing surface.
And hopefully that helps explain why I had such decision
paralysis around the terminology here.
Five of the bearings are all arranged in a straight line.
These are the main bearings
which hold the crankshaft in the block and keep it centered,
but the remaining four are wildly offset from the rest.
These eccentric bearings are what the pistons attach to.
The big round part at the bottom of the connecting rod
can be split in half by loosening these fasteners.
And then you can attach the piston and its bushings
to its respective bearing.
Now, I want to point out as I very loosely attach this,
that the mating surfaces here are both metal.
This is literally metal on metal contact,
and these components slide against each other as they spin around,
which feels problematic, doesn't it?
Keep that in mind as we continue.
If you're wondering why the crankshaft has these weird lobe things,
well, remember, this is the thing that spins.
And since the bearings that the pistons attach to are wildly offset from the center,
you need counterweights to keep it balanced.
And that's what these are.
This is roughly how fast the crankshaft spins when the engine is at idle!
And at redline, it can be spinning ten times as fast.
So you really want this thing
as perfectly balanced as you can possibly get it
to reduce vibration which could tear the engine apart.
And you can even see marks where small amounts of material were drilled
out of the counterweights after casting to make fine adjustments to balance.
But anyway, back to the pistons.
Once assembled, the pistons function
very much like your feet when pedaling a bicycle.
In fact, if you look at the crankshaft closely,
you'll see that on each end of it
is basically the exact same mechanism as the crank arm of a bike.
And here's what it looks like with all the pistons attached and the crankshaft turning.
There are several things wrong with this demonstration.
For instance, this is upside down.
But you'll notice that as the crankshaft rotates,
the four pistons move up and down into pairs.
When the outer two are at the bottom,
the inner two are at the top and Nissan Versa,
and they go round and round like a very strange Ferris wheel.
I mean, there is a lot of iron in there.
and here's what that looks like with the pistons and crankshaft inside the block
and the starter motor turning the crankshaft.
The block constrains the lateral movement of the pistons
which means the piston needs to be able to pivot back
and forth with respect to its connecting rod
as it flies around the crankshaft below.
That's why the connecting rod
is attached to the piston with what's called a wrist pin (or gudgeon pin if you're British).
That allows the top of the piston to sort of wiggle back and forth with respect to its connecting rod.
And that's how the piston can stay on a perfectly vertical track inside the block,
while its connecting rod is flailing all around below.
Here's a fun fact!
While editing this video,
I discovered that I accidentally deleted this section from the script.
So here's me putting it back!
When we are talking about an engine's size,
we're not actually talking about how large the cylinders in the block are.
At least not entirely.
We measure an engine's size by its displacement,
and that is defined by how much volume the pistons displace
as they move up and down inside the cylinders.
The pistons can only move down so far,
which only opens up so much space.
And in this engine, each piston moves
through a volume of 450cm³.
There are four of them, of course, and added together,
that means the pistons displace a total volume
of 1800cm³, or 1.8 liters.
And that is why this is a 1.8l engine.
However, we could increase this engine's displacement
without making the cylinders any bigger at all.
All we'd need to do is increase the stroke of the pistons
so that they travel farther down before they start heading back up, and boom, more displacement!
But that's much easier said than done, because to actually make that happen,
we'd need an entirely different and much larger crankshaft,
which will require redesigning the block.
And the power delivery characteristics of a piston engine can vary dramatically when the pistons have a longer stroke,
so it might not be desirable for all applications.
This is all very complicated,
but an engine's displacement presents a hard limit
to how much power it can theoretically produce,
and this is why, purportedly,
there is no replacement for displacement.
Then again, my daily driver has an engine displacement of null,
and yet it can still do 0 to 60 in well under five seconds.
So I'm not sure how true that is these days.
But anyway, let's move on.
And at this point, we've looked at nearly everything which lives inside the engine block.
But now you might have noticed a bit of a problem.
I said that the cylinders are combustion chambers
and expanding gases pushed the pistons down.
But, uh, right now
those gases don't have anything to push against.
This is just a weird series of cups
where the bottom can move up and down for some reason.
To actually turn all these into combustion chambers,
we need to seal it up.
And that's done with the cylinder head.
But also the piston rings.
Before we even talk about sealing the top of the chamber,
we also need a seal between the pistons themselves and the walls of the cylinders.
The pistons are actually slightly smaller
than the cylinders and can flop around in there a little bit.
So each one has not one, not two,
but two piston rings and a third oil control ring, which is a kind of piston ring,
but it doesn't have the same job.
The two piston rings near the top, known as compression rings, are simply metal rings with a bit of spring tension in them
which causes them to expand and fill the gap between the piston and the cylinder walls.
There are two of them because in order to put the ring on the piston,
it needs a gap, and that gap means the seal isn't so good.
So, well, we just throw a second one on there,
and ideally you'll position the gaps on opposite side -
Well, that one broke!
[through laughter] on opposite sides of the piston when putting the thing together.
So with the pistons now sufficiently sealed against the cylinders,
we have to seal the top of this thing so that we have an actual combustion chamber.
And that's what this guy is for.
This is the cylinder head
and it gets bolted to the top of the block and, with the help of the head gasket,
actually seals the cylinders up so they can become combustion chambers.
But this does far more than just that.
This is also what allows fresh air and fuel into the cylinders,
what expels exhaust from the cylinders,
and what ignites the air/fuel mixture.
Well, the spark plug is what does that for each cylinder.
But the spark plugs live in the cylinder head.
You can, see 'em poking out just there.
To actually let air and fuel into, as well as exhaust out of, the combustion chambers,
the cylinder head contains valves.
Like most modern engines there are four valves per cylinder, two each for intake and exhaust.
You really only need one of each,
but geometry makes it so you can have more total area
if you have two smaller valves rather than one big one,
and that allows the engine to breathe more easily.
From this side, the valves look like little circles,
but what they actually look like is golf tees.
And I'm totally serious.
They're basically just large golf tees.
I'd remove one to show you, but you see,
they're held shut with extremely powerful springs
and I do not have the guts to remove them for you.
So I bought these ones!
All that each of these little valves is really doing
is plugging a hole in the cylinder head.
On the sides of the cylinder head are the intake and exhaust ports.
These are where air and fuel goes into the engine on one side
and exhaust comes out of it on the other.
Look into those ports and you can see the backsides of the valves and the holes that they're plugging.
To keep that hole plugged up and the combustion chamber sealed,
a spring being held by this retaining mechanism
is constantly pulling up on the valve stem and keeping it firmly in its seat.
But if something pushes down hard enough to overcome the force of the spring,
the valves will poke out from where they sit
and suddenly the hole isn't plugged any longer.
There is now a pathway for air to make its way through this port and into the cylinder.
We now have all the ingredients to make a series of combustion chambers
that we can move gases into and out of under our control.
But what actually opens and closes the valves?
Well, these things,
but, more on them in a moment.
Now, we need to discuss the four stroke engine cycle.
Virtually every engine out there which isn't a very big diesel engine
or a very small weed whacker engine,
or in a very old car is a four stroke engine,
which means that when looking at a single cylinder,
the piston actually travels up and down
two complete times per combustion event.
First, it travels down during the intake stroke,
where the intake valve is open and fresh air and fuel is brought into the cylinder.
Then the valves will close and the piston travels back up
during the compression stroke, which squeezes that air and fuel into a tiny little space.
When the piston is at the top,
the spark plug fires
which ignites that mixture and forces the piston down during the power stroke,
which is the only stroke that actually produces motive power.
And finally, the piston moves back up again
with the exhaust valve open during the exhaust stroke,
where the piston will push the exhaust gases out of the cylinder.
And then that repeats.
That's intake, compression, power, and exhaust.
And for a helpful way to remember that,
which I'm sure many of you out there really want me to say...
suck, squeeze, bang, blow.
To make that sequence actually happen though,
the valves need to open and close in time with the movement of the pistons in the block.
And to make that happen, we use rotating camshafts like this.
These fellas are held captive with this bracket and spin above the valves.
When the pointy bit on each one of these cams, known as the lobe, lines up with the top of the valve,
it will press down on its respective valve and open it.
Here's what that looks like.
I want to point out yet again that this is metal on metal contact,
but you may notice in this footage that some kind of dark
liquid appears to be oozing out of various places
and getting all over the cams.
That's engine oil.
Where is it coming from?
The oil pump.
But hold on, we're not there yet.
First, I want to point out that the sequence in which the valves are opened
is programed by the physical shape of these things,
and that, along with the crankshaft design, dictates
the engine's firing order.
This engine doesn't fire the cylinders in sequence.
In fact, it skips around a bit with a firing order of 1 - 3 - 4 - 2
And if I slowly rotate the camshaft,
you'll see that the lobes stick out in that same order
because they have to open the valves in that order.
This engine could have been designed
with a simple 1 - 2 - 3 - 4 firing order,
but that would require a different crankshaft
where pistons one and three are at the top,
while two and four are at the bottom.
And when you do that with an inline four cylinder,
it tends to be even more of a vibrating mess than it already is.
Which is why the pistons are paired like this
and the firing order skips around a bit.
It's just a better balance.
But now we have a bit of a timing problem.
We need to make absolutely sure that those valves are opening
when they should be in relation to the pistons moving inside the engine block.
One way to do that would be to mechanically interlock the camshafts with the crankshaft,
which is exactly what this and any engine does,
but it's a little more complicated than you might imagine at first.
Recall this is a four stroke engine,
which means the pistons travel up and down twice for every time a valve opens.
But since the camshafts only make one rotation to open their valve,
that means we need the camshafts to be spinning at exactly half the rate of the crankshaft.
We need to do that so the crankshaft makes two rotations for every one rotation of the camshaft.
Luckily, that's easy to do with our old friend gears.
You may have noticed a couple of gears
on the end of the crankshaft away from the flex plate.
This smaller gear will drive the camshafts with the help of a chain.
That's this guy, the timing chain,
and it lives underneath this cover on the side of the engine.
Its job is to transmit motion from the crankshaft at the bottom
all the way up to the camshafts at the top.
Now the chain is going to keep them mechanically locked together,
but importantly, the crankshaft's gear has exactly half as many teeth
as the gears which drive the camshafts.
There are 23 teeth on the crankshaft gear
and 46 on both of these camshaft gears,
and that ratio will ensure it always takes exactly two rotations of the crankshaft
for the camshaft to make a single rotation.
And so long as this chain doesn't break,
they will remain perfectly locked together
such that the valves always open at the same time
in relation to the pistons inside the engine block.
Of course, we can actually fiddle with that while the engine is running,
and that's why this gear is so thick.
But we are not getting into that today!
At this point, I've covered all the mechanical basics of this engine.
And while this is a very common design,
it's by no means universal.
For one thing, lots of engines have more than
or even less than four cylinders.
Three cylinder engines have snuck their way into lots of cars these days, and many people haven't seemed to notice.
And of course, there's all those V6es and V8s
V engines are interesting
because they add a second bank of cylinders, but both banks of pistons share a single crankshaft.
This makes them only marginally larger than their inline counterparts,
while doubling the number of cylinders, and thus the power it can produce.
But more cylinders means a thirstier engine which costs more to operate,
which is why the old four banger is so dang common.
It's good enough.
but even within inline fours, there's a ton of variation.
This engine has separate camshafts for the intake valves and the exhaust valves,
and where these live is above the cylinder head.
And that makes this a dual overhead cam engine.
If you've ever seen DOHC on an engine cover
or like on the side of an old car as a badge,
that is literally referring to these two cams
and where they are in relation to the rest of the engine.
Some engines only use one camshaft,
but it will have more lobes on it, so it can actuate both the intake and the exhaust valves.
And that would be a single overhead cam engine,
SOHC.
But the camshaft isn't always over the heads.
Sometimes it lives in the block.
Many of those engines will use push rods,
basically metal sticks which ride on the cams,
and then they stick up into the head so that as the cams
rotate and the lobe pushes up on the stick,
the push rod will actuate itself against a rocker arm,
which then pushes down on the valves.
Those engines aren't that common these days because putting the cams over the heads has a lot of advantages.
Oh, and not every engine will use a timing chain.
For some reason we decided to start using timing belts made of rubber.
Okay, the reason was
that it made engines a little quieter
and it's not completely without merit.
But don't get me started on Ford's wet timing belt situation.
Just an utterly terrible idea they should be shamed for forever!
Regardless, engines with timing belts need regular replacement of that belt,
because many engines are what's called an interference engine,
where the valves will actually occupy the same physical space in the cylinder when they are open
that the pistons do when they're at the top.
So long as the engine is in time,
this doesn't matter because the pistons won't be near the valves when they're open.
But if the timing belt were to break
and the cams stop turning with a valve open and sticking down into the cylinder,
then as the crankshaft keeps on rotating, its respective piston will slam into that stuck valve
and cause lots of very expensive damage.
You don't want that, so you have to change the timing belt before it might break.
Timing chains are much, much less likely to break, but they can fail.
Usually, though, it's not catastrophic.
Instead, they simply start to stretch out a bit due to the links wearing down,
which makes valve timing sloppy, but not necessarily bad enough to be a problem.
Though if it does get bad enough to where the chain skips a tooth,
replacing a timing chain is a lot more involved than a belt,
so there is that to consider.
Right, and some pushrod engines don't use a belt or a chain.
If the camshaft is close enough to the crankshaft,
you can simply use interlocking gears.
But again, pushrod engines in cars are pretty much a relic of the past,
with some notable exceptions.
Oh, and also there's flathead engines where the valves aren't even in the heads.
But those are very old designs, and this rabbit hole is very, very deep.
And eventually you just have to stop.
Speaking of stop...
At this point, you're probably wondering
how any of this relates to the intro
and the thing about that little red light with a picture of an oiling can.
Well, everything we've been talking about is made of metal.
There's metal on metal contact everywhere inside this engine,
and those bits of metal spin really, really fast.
Or in the case of the pistons,
those bits of metal slide against each other really, really fast.
And that's going to cause a lot of damage unless you have lots and lots of lubrication.
And that is what engine oil is for.
Hanging off the bottom of the engine block is what's called the oil pan.
And this is effectively just a big bucket
which holds several quarts of motor oil.
Well, this engine has a weird design
and the block is split into two pieces.
So it doesn't really have an oil pan per se,
but the gist is the same.
This bottom half of the block alongside a plate,
which is the closest thing to an oil pan this engine has,
holds just about four liters of oil.
Apparently its precise oil capacity is four and 3/8 of a US quart.
And sitting below the crankshaft inside the oil pan
is this thing: the oil pump.
every engine which isn't a tiny little thing for like a lawnmower,
has an oil pump and in this one it's driven by the crankshaft via a second chain.
So long as the crankshaft is spinning, the oil pump will be too.
And what this does is suck engine oil out of this pan with this pickup tube,
force it through a filter to catch any contaminants,
and from there, the oil gets sent through many,
many tiny little holes and passageways throughout the engine.
Look closely at practically any part of an engine which moves,
and somewhere along the mating surface, you're going to find a hole which eventually leads back to the oil pump.
There are so many holes because when an engine is running,
oil is getting forcefully sprayed all over the dang place.
in fact, if you were wondering what some of these other holes in the head gasket were for,
well, some of these deliver oil under pressure from the block and into the cylinder head
so that it can lubricate the bearings of the camshafts
as well as the cam lobes as they slide along the valves.
That's why there's oil oozing out of different places in this footage.
Some of the other holes in this head gasket
allow that oil to return to the oil pan with the help of gravity,
though other holes are for engine coolant,
which we won't be talking about today.
Regardless, let's take a close look at the block and crankshaft bearings
because they reveal how this works the best.
This port with an orange O-ring on it is where oil is fed from the pump.
Once it finds its way in the block,
the oil flows through a series of tubes,
and you can sort of make out the shape of these tubes
and how it tees off here in both directions
by looking at the casting of the block.
If we look at the main bearing surfaces in the block,
we'll see that there's a hole in each one of its bushings.
If I remove the bushing, we'll find another larger hole behind it.
The oil pump forces a steady stream of oil through those holes whenever the crankshaft is spinning,
and that creates a fluid bearing.
Once there's oil pressure, the metal surfaces aren't actually touching each other.
Instead, they glide past each other with a thin film of oil between them.
That's how the bearings allow the engine to spin smoothly
despite the fact that they're literally just two pieces of metal.
But you'll notice that there's a channel or groove cut into the bushing here.
that is there to create a pathway for engine oil to make its way around the bearing
and into the crankshaft itself.
Notice that the bearing also has a hole.
That hole will move around as the engine spins,
but it will always be above that groove
and so will always be fed oil from the block.
And here we can actually see where the hole leads:
another hole on another bearing; the bearing that the connecting rod attaches to.
This is so that those bearings also get lots of lubrication
and we get that fluid bearing effect which keeps the metals from touching.
Which by the way in case it's not clear
oil is only under pressure inside all those passageways and ports and stuff.
There's a whole bunch more of them too which I haven't covered
inside the cylinder head to keep the camshafts lubricated
as well as the moving parts of the valves.
But once the oil makes its way out of whatever
confined space it used to be in,
it will just sort of ooze out.
And then it's got to get back to the bottom of the engine
so the oil pump can suck it up again.
So there is also a series of pathways throughout the engine
that will simply return any pooling oil to the bottom via gravity.
And that's why internal combustion engines need to be close to upright to operate.
If I were to turn this engine upside down and try and operate it,
or frankly, even on its side like it is now,
oil would be pooling in places it shouldn't go and the oil pump won't be able to get it.
And so the lubrication system just...
wouldn't work.
And that's bad because everything inside this engine moves stupidly fast.
If for whatever reason, the engine were to lose oil pressure,
then suddenly you have a very big problem.
That nice fluid bearing effect you get which keeps the metal parts from actually touching each other
will go away and now... metal parts are rubbing against each other very quickly,
and that's going to produce a lot of friction,
which will produce a lot of heat.
And before long the engine will seize,
meaning parts get fuzed together and it can no longer spin at all.
It is possible to get a seized engine unstuck,
but it will definitely be damaged in some way
and will likely have a greatly shortened lifespan.
So you never, ever, ever, ever want to run an engine
without knowing that there is sufficient oil pressure to keep that from happening.
And that is what that light is for.
It's connected to a pressure switch which in its resting state is closed.
In other words, when there is no oil pressure,
that switch completes a circuit which lights up that light.
This is what the pressure switch looks like.
It's an unassuming little thing.
Once the engine is turning,
the oil pump will start forcing oil into all those passageways.
And this port on the side is tapped off of those passages.
So sufficient oil pressure will open this pressure switch and extinguish the warning light.
This design allows you to check that the pressure switch is actually functional,
because if you simply turn the key without cranking the engine,
you should see the oil pressure light.
There's no oil pressure yet because the engine isn't running!
But when you start the engine,
that light should go out almost immediately.
And if it doesn't, there's a problem.
That problem isn't necessarily with the engine, of course.
It could simply be a bad pressure switch.
But that's a really risky assumption to make
because if that light and the switch is working as it should,
then if the light comes on, you are
then running your engine without oil pressure, which will kill it.
Oh, and fun fact eagle-eyed viewers of the catalytic converter video
may have noticed that this car had a bad pressure switch,
but it failed open.
The oil pressure light was never coming on
even without the engine running.
Here's me turning the key and that light is nowhere to be seen.
This meant the car could never warn me that I've lost oil pressure,
which isn't as bad as actually losing oil pressure, of course, but it's still quite bad.
Luckily, I happened to buy this entire engine for making videos
and it had its own oil pressure switch on there,
so I just swapped them over.
And now that light is actually doing its job.
Quick side note,
a lot of older cars didn't have an oil pressure warning light
and instead had an oil pressure gauge,
but that's mostly gone, much to the chagrin of John Davis of MotorWeek.
Some new vehicles still have oil pressure gauges,
but they're mainly found in big trucks
because getting to see an engine oil pressure readout makes some people feel big and manly and important.
But I mean, most people don't really care
how much oil pressure an engine is producing at any given moment.
And without knowledge of how much is actually correct,
a gauge isn't that useful anyway,
and that's why a simple pressure switch and warning light which indicates
"oil pressure is below a safe threshold," is frankly better.
Yeah, I said it.
Gearheads like to call these idiot lights
because we used to expect people to know they should be checking the gauges frequently.
In fact, some cars in the past had a little yellow warning light
which literally said "check gauges."
But while I too lament the loss of drivers being expected to know
a little more about how their cars work than they seem to now,
I think it's fair to say a warning light is all that's really needed,
but you do need to know what that warning light means.
On that note, why might you actually lose oil pressure?
Well, it's very rare for it to suddenly just happen.
I hope I haven't made it sound like this is something
you need to be extremely vigilant about all the time,
though you probably should watch the oil pressure light closely after you get an oil change,
and I'll explain that further in a moment.
If you're just driving around on a normal day, though,
it's extremely unlikely that your engine will suddenly lose oil pressure.
That would really only happen if the oil pump were to somehow fail.
And given that it's literally the most lubricated part in the whole engine
since it sits in oil and pumps it around,
that's quite rare.
It does happen, but it's extremely rare.
However, if your engine burns oil,
which it shouldn't, but it tends to start happening
when an engine gets very old and worn out.
Or if it wasn't designed very well,
well then the amount of oil inside your engine slowly drops as you use your car.
There's quite a good deal of margin for error,
so losing a quart of oil between oil changes is not likely to cause a problem.
But if your engine burns through a lot of oil,
then eventually the oil level can get low enough
that the oil pump starts to have trouble sucking any up through the intake tube.
If this is happening, the oil pressure light will likely come on and off, seemingly at random.
That is not as bad as not having any oil pressure at all, but it's still quite bad.
The bearings inside the engine aren't always getting good oil flow,
and they're going to start wearing out a lot faster than they should.
So you probably need to add some oil to your engine if that light is coming on intermittently.
But the most common reason you might one day lose oil pressure is when somebody makes a booboo.
For example, you went in to get an oil change
and the technician forgot to actually fill the engine
with new oil after they drained the old oil out.
Or maybe they forgot to put the drain plug back.
Or perhaps they didn't tighten it enough
and it backed itself out as you were driving
and your car puked all of its oil onto the ground.
To be clear, I don't want to make it sound like that happens all the time.
But seriously, after you get an oil change,
pay attention to that light for a while.
You really want to make sure it goes out quickly once the engine turns over and stays out.
But speaking of oil changes,
this car is due for one, so let's do it!
Why not?
In fact, I have no idea whether it's actually due for one.
But that's kind of why I'm doing it.
Changing your own oil is actually quite easy,
but I don't really recommend it because it's messy,
you have to deal with the old oil
(and yes, parts stores will take used oil for free, but it's still annoying),
And, it honestly hardly saves any money.
But why don't I show you the process?
Actually, first, if you don't know why you have to change the oil
every some thousand miles or so, well, here's why:
The oil gets really hot
and the piston rings aren't perfect.
Remember, there's a whole bunch of explosions going on in here!
Several every second, just at idle!
And the intense pressure inside the cylinders means
some combustion byproducts are going to end up getting past the piston rings
and into the crankcase where they'll mix with the engine oil and start to contaminate it.
That will eventually start to chemically break it down.
And if that's not bad enough,
the oil which clings to the cylinder walls gets extremely hot,
which also causes chemical breakdown.
Over time, this causes the oil to lose its lubricative properties,
and that means your engine can start to wear.
And if you're really overdue for an oil change,
little bits of stuff can precipitate out
of old engine oil and stick to things.
That's engine sludge.
And if it gets bad enough, it can start breaking things
by plugging up those tiny oil passageways.
So you gotta change your oil regularly to keep that from happening and to keep the engine healthy.
I'm deliberately not commenting on how often you should do that because nobody agrees.
But my basic advice is consult your owner's manual and maybe do it a little more often than it says you should.
But I've got one of those electric cars and it doesn't need oil changes.
How about that?
But this one does.
So first I'll get it up in the air a little bit.
You don't need a lift to do this.
If all you want to do is your own oil changes,
you can purchase these ramps and drive the front of your car onto them,
and that'll give you enough room to work with.
There's two things you need access to from the bottom:
the drain plug and the oil filter.
Though in some cars the oil filter is somewhere else
or possibly behind a cover of some sort.
You'll also need something to catch the used oil with, like this purpose made drain pan.
And then of course, you'll need new oil and a replacement filter.
Here's a five quart bottle of the cheapest oil I found in the store,
because this car is not worth getting fancy over,
and here's a replacement filter which fits the car.
Speaking of the oil,
your car's engine is going to call for a specific oil viscosity,
which some people refer to as its weight.
The Society of Automotive Engineers came up with a way to define motor oil viscosity
using a simple numbering scheme, and bigger numbers are more viscous.
This car needs 5W-30 motor oil.
And the cool thing about that
is that this oil has two different viscosity grades.
When the oil is cold, it has the same viscosity as a five weight oil.
That's the 5W, and the W is for winter.
But when the oil is hot
it has the viscosity of a 30 weight oil.
Now any oil loses viscosity and gets thinner as it gets hotter.
And this is no different.
But as the engine warms up, additives in this formulation
slow down that thinning process.
And that's how when it's hot, it has the same viscosity
as an unmodified 30 weight oil.
This is actually a really neat thing we figured out how to do.
And it means the engine has an easier time starting when it's cold,
but still has the same protection as a 30 weight oil once it's warmed up.
Right. And the breakdown of those additives over time
as the oil gets contaminated with combustion byproducts and whatnot, lowers the oil's viscosity grade.
And that's yet another reason you need to change it periodically.
So to do that, I'll start by draining the old oil from the engine.
But first I'm going to remove the filler cap up top,
which will allow that oil to leave the engine more quickly
by breaking the vacuum and letting air into the top of the engine.
Then I'll put the drain pan below the drain plug of the engine,
but I'm going to position it off-center.
You'll see why shortly.
Quick note, the transmission will also have a drain plug,
so make sure you know how to tell the engine and transmission apart before you drain the wrong thing.
Next, I'll use a wrench to crack the drain plug loose.
The engine is warmed up, by the way, to make the oil flow more easily.
with a gloved hand I'll then remove the plug.
If you keep pressing in on it while you back it out,
you can usually keep it from dripping any oil at all until you feel the threads start to click,
and then you can simply yoink it out quickly and hopefully not get any on your hands.
And now that it's flowing out of there,
you can see why I didn't center the drain pan.
As the old oil flows out, we'll deal with the oil filter.
This style of oil filter has built in threads and simply screws onto a fitting on the engine block.
Or in the case of this car,
whatever you call this part, which isn't really the block, but kind of is.
Anyway, these should only be put on hand tight,
which means they should come off easily,
but should is carrying a lot of weight there.
And that's why I have this oil filter wrench.
Once it starts coming loose, keep in mind
this thing is filled with oil and will be gross.
Many drain pans like this one have a spot
molded into them to put the used filter and let it drain out.
And now I'll take the new filter and with my gloved hand,
I'll smear just a little bit of the old oil onto the gasket
before screwing it onto the engine.
And again, this should only go on hand tight.
By the way, these claim to last long enough to only change the filter every other oil change.
But these are like five bucks, so you might as well just change it.
Its job is to trap things like metal shavings and keep them in the filter
before they plug up all those little parts and stuff,
which would be very bad.
So I don't think it's worth risking it.
Just replace it.
By this point, the engine is probably almost done draining the old oil out of itself.
But if for some reason it's still flowing, let it flow.
Once it's down to barely a trickle, though you can put the drain plug back.
Ideally, you'd replace this crush washer which seals that hole,
but I did not get a replacement, so I will be reusing the old one
Once I've started threading the plug by hand,
I'll then reach for an impact wrench.
Except I'm joking.
Don't ever use power tools for this.
If you screw up the threads on the oil pan,
this oil change went from an easy job to a very bad day.
So only use hand tools when dealing with drain plugs.
I even looked up the torque spec for this guy.
It's 34.3 Newton meters or 25 pound feet.
And I used this old torque wrench which I have no idea whether it's well calibrated or not at this point,
but hey.
It's the thought that counts.
[click]
And now we're done down here.
But we're very much not done done because the engine no longer has any oil in it!
Well, it probably has about half a quart stuck in there based on how much of a mess
this one made when getting some of this footage,
but it's definitely not enough for it to run without damage.
If I were to start it now, that would be very bad.
Oh, fun fact, did you know engines are dishwasher safe?
The dishwasher would not agree, but, uh,
it did clean it.
Anyway,
now we have to put new oil into the engine,
which is done via the filler cap.
This is literally just a big hole that leads into the timing cover.
Look, you can even see the timing chain a little bit.
Pour new oil into here and it will fall down into the oil pan...
or whatever this is- let's just call it the oil sump.
However, this car will not need this entire bottle of oil.
In fact, it would be overfilled if I put the whole thing in
and an engine with too much oil is also a problem.
So I'll put most of it in there,
but then I'll have to check how much oil is inside using the dipstick.
Which is literally just a stick in a tube.
And that tube leads to the engine's oil sump.
The stick has markings on the end,
and once you've cleaned it using a rag or paper towel or whatever,
you'll stick it down into the tube all the way and then pull it back out.
The tip of the stick should have poked down into the oil,
and you'll be able to see the oil level when you pull it out.
If you're not seeing any oil towards the markings,
you're probably still about a quart shy and you'll need to add a good deal more.
Just keep adding a little bit at a time, though, and repeat the oil level check process,
and eventually you'll start to see the oil in the range.
I'm going to shoot for just below the full mark,
which will account for any oil
which might be sticking to the timing chain and junk.
And once it's full,
well that's an oil change.
It's really quite straightforward.
Now all that's left to do besides dealing with the used oil and filter, of course,
is to put the oil cap back on and start the engine.
But now a note on prefilling the oil filter.
Some people insist that you should fill the oil filter
with clean oil before putting it on to the engine.
The theory is that this oil filter is currently filled with air and not oil,
and so when I start the engine,
there will be a brief moment where the engine is running without oil pressure.
But personally, I think this is a very silly thing to obsess over.
Why?
Well, because not only is the oil filter filled with air right now,
but so is every single one of the passageways inside the engine.
So forgive me for not thinking
filling this with oil is going to make a huge difference.
Granted, this engine has a tiny little filter and some engines have much bigger ones.
But why don't we take a look at how quickly
that oil pressure light goes out once I start the engine?
Okay.
I just changed the oil.
Let's crank it up.
[engine starts]
Yeah.
What, one second?
One extra second.
It's not a big deal.
I mean, you go ahead and fill these things with oil if you want to,
but I feel like doing that is just creating another mess which isn't doing much if anything at all.
The film of old oil that's sticking to the bearings, etc.
is going to be enough to prevent damage in the 2 or 3 seconds
it takes the oil pump to fill even a really big oil filter.
Regardless, now that the engine is running, it's prudent to check the oil filter and drain plug for any signs of leaks.
And assuming there are none,
you're done!
We've looked at a great deal of stuff today,
but we've just been looking at the basic mechanical parts of the engine.
Yeah, there are a whole lot of spinny bits in there,
and they all need lots of lube to keep on spinning,
but they don't start spinning unless a whole lot of other stuff happens.
For instance, we need to deliver fuel to the combustion chambers,
and we need to ignite that fuel with a spark plug.
We use a computer to do those things,
and we've been doing that for decades now.
But the computer needs to know
precisely where each part of this engine is,
so it can tell when it should do those things.
In the next video on engine management tech, we'll be looking closely at,
well, that part, the management part,
because while this is a very intricate and fascinating piece of machinery,
it is literally useless without the digital system
which controls the spark plugs, the fuel injectors
and even the intake valve timing.
I'll be covering all of that in the next video in this series,
so stay tuned.
♫ load-bearingly smooth jazz ♫
[whirring sound is increasing in speed]
[schwoop]
[banging]
[comically metallic crash]
It's fine!
It's fine.
Nothing happened.
It just fell off the table.
It's fine.
This is the crank pulley and it provides power for the engine accessories.
That's not working.
and it provides power for engine accessories such as the alternator,
the air conditioning compressor...
I thought you would behave a little better.
You didn't. You didn't.
[oh no here we go again]
[the sounds weren't as funny this time]
It's fine.
Nothing happened.
It's fine.
So now I guess I need to start plotting my atonement for the bearing/journal decision.
Does one plot an atonement?
Well that's not important right now.
What is important is that you imagine the animated character Doug Funnie writing in his bearing.
For some of you, that hurt.