Oil pressure is the only thing keeping an engine alive

[00:00] If there's one light on your car's

[00:05] it's this one:

[00:06] the oil pressure warning light.

[00:08] It usually looks like a little oiling can.

[00:11] And if that light comes on while you're driving,

[00:14] that means you should pull over and

[00:19] and then call a tow truck.

[00:21] And I'm not kidding.

[00:23] If that light comes on,

[00:24] your engine may be mere minutes away from self-destruction.

[00:29] And so continuing to drive is a very risky choice to make.

[00:33] Now, if you're wondering why exactly the engine

[00:39] that's the point of this video.

[00:41] Today we're going to explore the mechanical basics of the internal combustion engine,

[00:46] with a particular focus on its lubrication system

[00:53] There's a lot of stuff going on inside one of these contraptions,

[00:57] 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.

[01:04] Now, if you're a gearhead or even just gearhead-adjacent,

[01:08] there's probably not much you're going to learn here.

[01:10] But if you don't really know that much

[01:14] and really how they keep themselves working,

[01:17] well I think you'll find this video to be quite informative.

[01:21] Before we really dive in, though,

[01:22] there's something you should know about the rest of the lights on your car's instrument cluster.

[01:27] And that's something is the rest of them!

[01:30] Because they all mean very important things

[01:35] They're even color coded to convey their urgency and meaning.

[01:39] Red lights are bad and need your attention now

[01:43] because they indicate an unsafe condition

[01:48] Yellow lights are warnings which can vary in severity

[01:51] but probably don't need your immediate attention.

[01:55] And other colors are usually reserved for simple information,

[01:58] like the blue light that warns you your high beams are on

[02:01] so please shut them off unless you're in the middle of the country — that's not for use with other cars around!

[02:06] Or the white or green status

[02:11] If you want to know just what exactly all those lights mean,

[02:14] your car will have an owner's manual somewhere

[02:17] and there's going to be a handy little section which explains each and every one of them and why they might light up.

[02:23] I'd highly encourage looking at that section of the manual

[02:26] and committing those details to memory.

[02:29] But anyway, this is a video about the engine and how it works.

[02:32] So let's dig into it.

[02:34] First, though, if you'll indulge me,

[02:36] here's a brief overview of how electric cars work:

[02:39] [two toots of the drill]

[02:41] But bigger.

[02:42] And now let's take a look at this Renault-Nissan MR-18DE,

[02:46] the engine which powers the venerable Nissan Cube.

[02:50] Let me just, uh, take it apart real quick.

[02:59] Okay,

[03:01] this is the engine block.

[03:03] It's really nothing more than an intricately cast

[03:08] but it's the heart of the engine and contains the cylinders.

[03:11] In this case, there are four of them,

[03:13] and they're all arranged in a straight line,

[03:15] which makes this an inline four cylinder engine.

[03:18] Probably the most common type of engine out there in cars.

[03:22] Not all four cylinder engines are alike, of course;

[03:25] these cylinders come in many different sizes,

[03:29] and they're not always arranged in a line.

[03:32] We'll talk more about that later, though.

[03:34] Oh also sometimes there aren't cylinders at all!

[03:36] But that's mainly a Mazda thing they only sometimes do

[03:40] because rotary engines are equal parts cool and terrible.

[03:44] But they're committed to them!

[03:46] Sometimes - for special occasions.

[03:48] Anyway, the cylinders are each a combustion chamber.

[03:52] The idea is to fill these cylinders with a mixture of air and fuel,

[03:55] and then ignite that mixture so it...

[03:58] expands very rapidly.

[04:01] I would say that mixture explodes,

[04:03] but it's not technically an explosion.

[04:06] What's really happening is that the carbon dioxide

[04:08] and water vapor that are produced in the combustion process

[04:11] have a much larger volume

[04:16] and that rapid expansion of hot gases

[04:20] can be harnessed and turned into mechanical work.

[04:23] And to do that we use pistons.

[04:26] Each cylinder gets a piston just like this inserted from the bottom,

[04:30] and these pistons are able to

[04:35] During a combustion event, as the mixture of hot gases inside the cylinder rapidly expands

[04:41] these pistons are forced downward into the engine block.

[04:44] And that's how we convert the chemical

[04:50] Now, the goal of this engine is to spin the wheels of a car.

[04:54] So ultimately the engine produces rotational movement.

[04:57] And since the pistons move up and down inside the cylinders,

[05:01] we're going to need a mechanism to translate

[05:07] If you noticed the weird stick thing

[05:11] well, this is the connecting rod

[05:16] to this thing.

[05:17] This is the crankshaft, and it is the thing that spins.

[05:22] The tachometer, the gauge which tells you engine RPM,

[05:25] is telling you how quickly this literal thing

[05:31] Now we're going to look at this closely

[05:36] But first I want to point out that the crankshaft

[05:41] That is how we actually make this spinning crankshaft

[05:44] do useful things for us.

[05:47] Bolted to one side of it

[05:48] is this large rusty wheel with teeth on its edges.

[05:52] This is what's known as a flexplate.

[05:54] The teeth on its circumference are there

[06:00] and turn the crankshaft

[06:04] But the rest of this connects the engine to the transmission

[06:08] so that once the engine is running

[06:10] the spinning crankshaft can spin the wheels of the car.

[06:14] Technical note: if you were expecting me to call this a flywheel,

[06:18] well, this is not a flywheel.

[06:20] It's a flexplate.

[06:22] What's the difference?

[06:23] Well, flywheels are used with manual transmissions,

[06:27] while flexplates are used with automatic transmissions.

[06:31] In a car with an automatic,

[06:35] the flexplate gets fastened

[06:38] and the engine and transmission

[06:42] But flywheels are completely different.

[06:45] They're used with manual transmissions

[06:47] and are not really fastened to the transmission at all,

[06:51] since in a stick shift the engine and transmission

[06:58] The clutch sort of presses up against the flywheel

[07:01] when engaged to connect the transmission to the engine,

[07:05] and it moves away from the flywheel when disengaged to separate them.

[07:09] And because of this, flywheels have a smooth surface

[07:12] on the outer side which the clutch pushes against.

[07:16] It's also quite a lot thicker and heavier than a flexplate

[07:19] to give the crankshaft more rotational momentum:

[07:22] helpful when getting the car moving from a stop.

[07:25] This Nissan Cube has a manual transmission,

[07:28] so its engine has a flywheel

[07:32] but everything else is identical.

[07:35] Now, while moving the car is the main thing the spinning crankshaft has to do,

[07:40] it also has to do things like generate electricity to keep the car's battery charged.

[07:45] And that needs to happen whether the wheels are moving or not.

[07:48] Which is why the other end of the crankshaft

[07:53] But on this side, all we have attached to it is the small pulley.

[07:58] This is the crank pulley

[08:00] and it provides power for engine accessories such as the alternator,

[08:03] air conditioning compressor and water pump via a drive belt.

[08:08] The pulley simply bolts on to the end of the crankshaft here...

[08:12] with this large bolt.

[08:14] Oh, and like in many engines,

[08:16] that pulley has some rubber like material in there

[08:19] to allow it to function as a harmonic balancer.

[08:22] But that's not important right now.

[08:24] What is important right now

[08:25] is how the uppy downy pistons actually make

[08:31] To explain, I want you to focus on these very shiny

[08:34] and perfectly circular surfaces you can find on the crankshaft.

[08:38] These are bearings,

[08:40] just plain bearings.

[08:42] which is a dad joke because

[08:46] [voiceover]

[08:49] with some notes on terminology.

[08:51] I made the mistake when writing this script

[08:53] of letting a technical definition supersede

[08:56] the common language most people use.

[08:59] These are indeed plain bearings,

[09:01] but they belong to a subset of

[09:06] And the circular, shiny things we're looking at on the crankshaft

[09:08] are usually referred to as the journals.

[09:12] But here's the thing.

[09:14] Journal is simply another word for shaft.

[09:18] All these things are is a polished, circular shaft

[09:21] which spins inside of a stationary circle,

[09:24] which wraps around and holds on to the shaft.

[09:26] Once put together, it's really just two concentric circles

[09:30] where one spins and the other doesn't.

[09:32] And both the spinning journal and its stationary

[09:36] holder are a bearing surface,

[09:38] which is what I wanted to highlight in this video.

[09:41] The interface between those two bearing surfaces

[09:44] is what really matters to the point here.

[09:46] And from either one's individual perspective,

[09:50] the other part is what's spinning.

[09:51] And so that's why I ultimately chose to refer to these as bearings.

[09:56] But I understand a lot of people will be very annoyed by that choice.

[09:59] And so... sorry about that.

[10:02] They consist of that smooth,

[10:04] shiny part in the center of the crankshaft

[10:06] and a thin bushing which surrounds it.

[10:09] You can see half of the bushings here in the block.

[10:12] [voiceover]

[10:13] See, this right here explains the problem.

[10:15] This is literally the bearing.

[10:17] This is the bearing surface.

[10:19] But technically it is a bushing.

[10:21] However, when people rebuild engines,

[10:23] they're going to refer to these things

[10:25] as the bearing because it's the bearing surface.

[10:28] And hopefully that helps explain why I had such decision

[10:31] paralysis around the terminology here.

[10:33] Five of the bearings are all arranged in a straight line.

[10:37] These are the main bearings

[10:38] which hold the crankshaft in the block and keep it centered,

[10:42] but the remaining four are wildly offset from the rest.

[10:48] These eccentric bearings are what the pistons attach to.

[10:52] The big round part at the bottom of the connecting rod

[10:55] can be split in half by loosening these fasteners.

[10:58] And then you can attach the piston and its bushings

[11:01] to its respective bearing.

[11:04] Now, I want to point out as I very loosely attach this,

[11:08] that the mating surfaces here are both metal.

[11:13] This is literally metal on metal contact,

[11:16] and these components slide against each other as they spin around,

[11:21] which feels problematic, doesn't it?

[11:24] Keep that in mind as we continue.

[11:26] If you're wondering why the

[11:31] well, remember, this is the thing that spins.

[11:34] And since the bearings that the pistons

[11:40] you need counterweights to keep it balanced.

[11:42] And that's what these are.

[11:45] This is roughly how fast the

[11:50] And at redline, it can be spinning ten times as fast.

[11:54] So you really want this thing

[11:56] as perfectly balanced as you can possibly get it

[11:59] to reduce vibration which could tear the engine apart.

[12:02] And you can even see marks

[12:06] out of the counterweights after casting to make fine adjustments to balance.

[12:11] But anyway, back to the pistons.

[12:13] Once assembled, the pistons function

[12:16] very much like your feet when pedaling a bicycle.

[12:19] In fact, if you look at the crankshaft closely,

[12:21] you'll see that on each end of it

[12:23] is basically the exact same

[12:28] And here's what it looks like with

[12:33] There are several things wrong with this demonstration.

[12:37] For instance, this is upside down.

[12:39] But you'll notice that as the crankshaft rotates,

[12:42] the four pistons move up and down into pairs.

[12:45] When the outer two are at the bottom,

[12:47] the inner two are at the top and Nissan Versa,

[12:50] and they go round and round like a very strange Ferris wheel.

[12:54] I mean, there is a lot of iron in there.

[12:57] and here's what that looks like with the pistons and crankshaft inside the block

[13:01] and the starter motor turning the crankshaft.

[13:04] The block constrains the lateral movement of the pistons

[13:07] which means the piston needs to be able to pivot back

[13:10] and forth with respect to its connecting rod

[13:13] as it flies around the crankshaft below.

[13:16] That's why the connecting rod

[13:18] is attached to the piston with what's called a wrist pin

[13:23] That allows the top of the piston to sort of wiggle back and forth with respect to its connecting rod.

[13:28] And that's how the piston can stay on

[13:33] while its connecting rod is flailing all around below.

[13:37] Here's a fun fact!

[13:39] While editing this video,

[13:40] I discovered that I accidentally deleted this section from the script.

[13:44] So here's me putting it back!

[13:46] When we are talking about an engine's size,

[13:49] we're not actually talking about

[13:54] At least not entirely.

[13:57] We measure an engine's size by its displacement,

[14:00] and that is defined by how much volume the pistons displace

[14:05] as they move up and down inside the cylinders.

[14:08] The pistons can only move down so far,

[14:11] which only opens up so much space.

[14:14] And in this engine, each piston moves

[14:16] through a volume of 450cm³.

[14:20] There are four of them, of course, and added together,

[14:23] that means the pistons displace a total volume

[14:26] of 1800cm³, or 1.8 liters.

[14:31] And that is why this is a 1.8l engine.

[14:35] However, we could increase this engine's displacement

[14:39] without making the cylinders any bigger at all.

[14:42] All we'd need to do is increase the stroke of the pistons

[14:46] so that they travel farther down before they start

[14:53] But that's much easier said than done, because to actually make that happen,

[14:57] we'd need an entirely different and much larger crankshaft,

[15:02] which will require redesigning the block.

[15:05] And the power delivery characteristics of a piston engine can vary dramatically when the pistons have a longer stroke,

[15:12] so it might not be desirable for all applications.

[15:16] This is all very complicated,

[15:18] but an engine's displacement presents a hard limit

[15:22] to how much power it can theoretically produce,

[15:24] and this is why, purportedly,

[15:27] there is no replacement for displacement.

[15:30] Then again, my daily driver has an engine displacement of null,

[15:35] and yet it can still do 0 to 60 in well under five seconds.

[15:39] So I'm not sure how true that is these days.

[15:41] But anyway, let's move on.

[15:43] And at this point, we've looked at nearly everything

[15:48] But now you might have noticed a bit of a problem.

[15:52] I said that the cylinders are combustion chambers

[15:55] and expanding gases pushed the pistons down.

[15:59] But, uh, right now

[16:00] those gases don't have anything to push against.

[16:03] This is just a weird series of cups

[16:05] where the bottom can move up and down for some reason.

[16:09] To actually turn all these into combustion chambers,

[16:12] we need to seal it up.

[16:14] And that's done with the cylinder head.

[16:16] But also the piston rings.

[16:19] Before we even talk about sealing the top of the chamber,

[16:22] we also need a seal between the pistons themselves and the walls of the cylinders.

[16:27] The pistons are actually slightly smaller

[16:29] than the cylinders and can flop around in there a little bit.

[16:32] So each one has not one, not two,

[16:35] but two piston rings and a third oil control ring,

[16:40] but it doesn't have the same job.

[16:42] The two piston rings near the top, known as compression rings, are simply metal rings with a bit of spring tension in them

[16:50] which causes them to expand and fill

[16:56] There are two of them because

[16:59] it needs a gap, and that gap means the seal isn't so good.

[17:04] So, well, we just throw a second one on there,

[17:06] and ideally you'll position the gaps on opposite side -

[17:10] Well, that one broke!

[17:11] [through laughter]

[17:15] So with the pistons now

[17:19] we have to seal the top of this thing

[17:24] And that's what this guy is for.

[17:27] This is the cylinder head

[17:29] and it gets bolted to the top of the block and, with the help of the head gasket,

[17:33] actually seals the cylinders up

[17:38] But this does far more than just that.

[17:41] This is also what allows fresh air and fuel into the cylinders,

[17:45] what expels exhaust from the cylinders,

[17:47] and what ignites the air/fuel mixture.

[17:52] Well, the spark plug is what does that for each cylinder.

[17:55] But the spark plugs live in the cylinder head.

[17:56] You can, see 'em poking out just there.

[17:59] To actually let air and fuel into,

[18:05] the cylinder head contains valves.

[18:07] Like most modern engines there are four valves per cylinder,

[18:13] You really only need one of each,

[18:15] but geometry makes it so you can have more total area

[18:18] if you have two smaller valves rather than one big one,

[18:22] and that allows the engine to breathe more easily.

[18:25] From this side, the valves look like little circles,

[18:28] but what they actually look like is golf tees.

[18:32] And I'm totally serious.

[18:33] They're basically just large golf tees.

[18:36] I'd remove one to show you, but you see,

[18:38] they're held shut with extremely powerful springs

[18:41] and I do not have the guts to remove them for you.

[18:45] So I bought these ones!

[18:47] All that each of these little valves is really doing

[18:50] is plugging a hole in the cylinder head.

[18:53] On the sides of the cylinder head are the intake and exhaust ports.

[18:57] These are where air and fuel goes into the engine on one side

[19:01] and exhaust comes out of it on the other.

[19:03] Look into those ports and you can see the backsides of the valves and the holes that they're plugging.

[19:10] To keep that hole plugged up and the combustion chamber sealed,

[19:13] a spring being held by this retaining mechanism

[19:16] is constantly pulling up on the

[19:22] But if something pushes down hard enough to overcome the force of the spring,

[19:26] the valves will poke out from where they sit

[19:29] and suddenly the hole isn't plugged any longer.

[19:32] There is now a pathway for air to make its way through this port and into the cylinder.

[19:37] We now have all the ingredients

[19:42] that we can move gases into and out of under our control.

[19:46] But what actually opens and closes the valves?

[19:51] Well, these things,

[19:53] but, more on them in a moment.

[19:56] Now, we need to discuss the four stroke engine cycle.

[20:00] Virtually every engine out there

[20:04] or a very small weed whacker engine,

[20:05] or in a very old car is a four stroke engine,

[20:09] which means that when looking at a single cylinder,

[20:12] the piston actually travels up and down

[20:15] two complete times per combustion event.

[20:18] First, it travels down during the intake stroke,

[20:21] where the intake valve is open and fresh air

[20:27] Then the valves will close and the piston travels back up

[20:30] during the compression stroke, which squeezes

[20:36] When the piston is at the top,

[20:37] the spark plug fires

[20:39] which ignites that mixture and forces the piston down during the power stroke,

[20:43] which is the only stroke that actually produces motive power.

[20:47] And finally, the piston moves back up again

[20:49] with the exhaust valve open during the exhaust stroke,

[20:53] where the piston will push the exhaust gases out of the cylinder.

[20:57] And then that repeats.

[20:58] That's intake, compression, power, and exhaust.

[21:02] And for a helpful way to remember that,

[21:03] which I'm sure many of you out there really want me to say...

[21:07] suck squeeze bang blow.

[21:10] To make that sequence actually happen though,

[21:12] the valves need to open and close in time

[21:18] And to make that happen, we use rotating camshafts like this.

[21:24] These fellas are held captive with

[21:29] When the pointy bit on each one of these cams,

[21:35] it will press down on its respective valve and open it.

[21:40] Here's what that looks like.

[21:42] I want to point out yet again that this is metal on metal contact,

[21:46] but you may notice in this footage that some kind of dark

[21:49] liquid appears to be oozing out of various places

[21:52] and getting all over the cams.

[21:55] That's engine oil.

[21:57] Where is it coming from?

[21:59] The oil pump.

[22:00] But hold on, we're not there yet.

[22:02] First, I want to point out that the sequence

[22:06] is programed by the physical shape of these things,

[22:09] and that, along with the crankshaft design, dictates

[22:12] the engine's firing order.

[22:15] This engine doesn't fire the cylinders in sequence.

[22:18] In fact, it skips around a bit with a firing order of 1 - 3 - 4 - 2

[22:24] And if I slowly rotate the camshaft,

[22:27] you'll see that the lobes stick out in that same order

[22:31] because they have to open the valves in that order.

[22:35] This engine could have been designed

[22:37] with a simple 1 - 2 - 3 - 4 firing order,

[22:40] but that would require a different crankshaft

[22:43] where pistons one and three are at the top,

[22:46] while two and four are at the bottom.

[22:48] And when you do that with an inline four cylinder,

[22:51] it tends to be even more of a vibrating mess than it already is.

[22:55] Which is why the pistons are paired like this

[22:57] and the firing order skips around a bit.

[23:00] It's just a better balance.

[23:02] But now we have a bit of a timing problem.

[23:05] We need to make absolutely sure that those valves are opening

[23:09] when they should be in relation

[23:15] One way to do that would be to mechanically interlock

[23:21] which is exactly what this and any engine does,

[23:24] but it's a little more complicated than you might imagine at first.

[23:28] Recall this is a four stroke engine,

[23:30] which means the pistons travel up and down twice for every time a valve opens.

[23:36] But since the camshafts only make one rotation to open their valve,

[23:42] that means we need the camshafts to be spinning

[23:50] We need to do that so the crankshaft makes two rotations for every one rotation of the camshaft.

[23:56] Luckily, that's easy to do with our old friend gears.

[24:01] You may have noticed a couple of gears

[24:02] on the end of the crankshaft away from the flex plate.

[24:06] This smaller gear will drive

[24:11] That's this guy, the timing chain,

[24:14] and it lives underneath this cover on the side of the engine.

[24:17] Its job is to transmit motion from the crankshaft at the bottom

[24:22] all the way up to the camshafts at the top.

[24:25] Now the chain is going to keep

[24:29] but importantly, the crankshaft's

[24:35] as the gears which drive the camshafts.

[24:38] There are 23 teeth on the crankshaft gear

[24:40] and 46 on both of these camshaft gears,

[24:44] and that ratio will ensure it always takes

[24:49] for the camshaft to make a single rotation.

[24:52] And so long as this chain doesn't break,

[24:55] they will remain perfectly locked together

[24:57] such that the valves always open at the same time

[25:00] in relation to the pistons inside the engine block.

[25:04] Of course, we can actually

[25:08] and that's why this gear is so thick.

[25:10] But we are not getting into that today!

[25:13] At this point, I've covered all the

[25:17] And while this is a very common design,

[25:20] it's by no means universal.

[25:22] For one thing, lots of engines have more than

[25:25] or even less than four cylinders.

[25:28] Three cylinder engines have snuck their way into lots of cars

[25:33] And of course, there's all those V6es and V8s

[25:37] V engines are interesting

[25:39] because they add a second bank of cylinders,

[25:47] This makes them only marginally larger

[25:51] while doubling the number of cylinders,

[25:56] But more cylinders means

[26:00] which is why the old four banger is so dang common.

[26:04] It's good enough.

[26:06] but even within inline fours, there's a ton of variation.

[26:10] This engine has separate camshafts

[26:15] and where these live is above the cylinder head.

[26:19] And that makes this a dual overhead cam engine.

[26:23] If you've ever seen DOHC on an engine cover

[26:25] or like on the side of an old car as a badge,

[26:28] that is literally referring to these two cams

[26:32] and where they are in relation to the rest of the engine.

[26:35] Some engines only use one camshaft,

[26:39] but it will have more lobes on it, so it can actuate

[26:44] And that would be a single overhead cam engine,

[26:47] SOHC.

[26:49] But the camshaft isn't always over the heads.

[26:51] Sometimes it lives in the block.

[26:54] Many of those engines will use push rods,

[26:57] basically metal sticks which ride on the cams,

[27:00] and then they stick up into the head so that as the cams

[27:04] rotate and the lobe pushes up on the stick,

[27:06] the push rod will actuate itself against a rocker arm,

[27:09] which then pushes down on the valves.

[27:12] Those engines aren't that common these days because putting the cams over the heads has a lot of advantages.

[27:18] Oh, and not every engine will use a timing chain.

[27:23] For some reason we decided

[27:29] Okay, the reason was

[27:31] that it made engines a little quieter

[27:33] and it's not completely without merit.

[27:34] But don't get me started on Ford's wet timing belt situation.

[27:39] Just an utterly terrible idea

[27:44] Regardless, engines with timing belts

[27:49] because many engines are what's called an interference engine,

[27:53] where the valves will actually occupy

[27:58] that the pistons do when they're at the top.

[28:01] So long as the engine is in time,

[28:03] this doesn't matter because the pistons

[28:07] But if the timing belt were to break

[28:10] and the cams stop turning with a valve open

[28:15] then as the crankshaft keeps on rotating,

[28:21] and cause lots of very expensive damage.

[28:25] You don't want that, so you have to change

[28:31] Timing chains are much, much

[28:37] Usually, though, it's not catastrophic.

[28:39] Instead, they simply start to stretch out a bit due to the links wearing down,

[28:44] which makes valve timing sloppy,

[28:50] Though if it does get bad enough to where the chain skips a tooth,

[28:54] replacing a timing chain is a lot more involved than a belt,

[28:58] so there is that to consider.

[29:02] Right, and some pushrod engines don't use a belt or a chain.

[29:05] If the camshaft is close enough to the crankshaft,

[29:08] you can simply use interlocking gears.

[29:11] But again, pushrod engines in cars

[29:15] with some notable exceptions.

[29:17] Oh, and also there's flathead engines where

[29:21] But those are very old designs,

[29:25] And eventually you just have to stop.

[29:27] Speaking of stop...

[29:28] At this point, you're probably wondering

[29:30] how any of this relates to the intro

[29:32] and the thing about that little red light

[29:36] Well, everything we've been talking about is made of metal.

[29:41] There's metal on metal contact everywhere inside this engine,

[29:45] and those bits of metal spin really, really fast.

[29:50] Or in the case of the pistons,

[29:52] those bits of metal slide against each other really, really fast.

[29:55] And that's going to cause a lot of damage

[30:03] And that is what engine oil is for.

[30:06] Hanging off the bottom of the

[30:10] And this is effectively just a big bucket

[30:12] which holds several quarts of motor oil.

[30:16] Well, this engine has a weird design

[30:18] and the block is split into two pieces.

[30:21] So it doesn't really have an oil pan per se,

[30:23] but the gist is the same.

[30:26] This bottom half of the block alongside a plate,

[30:29] which is the closest thing to an oil pan this engine has,

[30:32] holds just about four liters of oil.

[30:35] Apparently its precise oil capacity is four and 3/8 of a US quart.

[30:41] And sitting below the crankshaft inside the oil pan

[30:46] is this thing: the oil pump.

[30:48] every engine which isn't a tiny little thing for like a lawnmower,

[30:52] has an oil pump and in this one it's driven

[30:58] So long as the crankshaft is spinning, the oil pump will be too.

[31:02] And what this does is suck engine oil

[31:07] force it through a filter to catch any contaminants,

[31:09] and from there, the oil gets sent through many,

[31:12] many tiny little holes and passageways throughout the engine.

[31:17] Look closely at practically any part of an engine which moves,

[31:20] and somewhere along the mating surface, you're going to find a hole which eventually leads back to the oil pump.

[31:28] There are so many holes because when an engine is running,

[31:31] oil is getting forcefully sprayed all over the dang place.

[31:34] in fact, if you were wondering

[31:40] well, some of these deliver oil under pressure

[31:45] so that it can lubricate the bearings of the camshafts

[31:48] as well as the cam lobes as they slide along the valves.

[31:51] That's why there's oil oozing out of different places in this footage.

[31:55] Some of the other holes in this head gasket

[31:57] allow that oil to return to the oil pan with the help of gravity,

[32:01] though other holes are for engine coolant,

[32:03] which we won't be talking about today.

[32:06] Regardless, let's take a close

[32:10] because they reveal how this works the best.

[32:13] This port with an orange O-ring on it

[32:18] Once it finds its way in the block,

[32:20] the oil flows through a series of tubes,

[32:23] and you can sort of make out the shape of these tubes

[32:26] and how it tees off here in both directions

[32:28] by looking at the casting of the block.

[32:32] If we look at the main bearing surfaces in the block,

[32:35] we'll see that there's a hole in each one of its bushings.

[32:38] If I remove the bushing, we'll find another larger hole behind it.

[32:43] The oil pump forces a steady stream of oil through those holes whenever the crankshaft is spinning,

[32:49] and that creates a fluid bearing.

[32:52] Once there's oil pressure, the metal surfaces

[32:57] Instead, they glide past each other with a thin film of oil between them.

[33:02] That's how the bearings allow the engine to spin smoothly

[33:05] despite the fact that they're literally just two pieces of metal.

[33:09] But you'll notice that there's a channel

[33:14] that is there to create a pathway for engine oil

[33:19] and into the crankshaft itself.

[33:22] Notice that the bearing also has a hole.

[33:25] That hole will move around as the engine spins,

[33:28] but it will always be above that groove

[33:30] and so will always be fed oil from the block.

[33:34] And here we can actually see where the hole leads:

[33:37] another hole on another bearing; the bearing

[33:42] This is so that those bearings also get lots of lubrication

[33:46] and we get that fluid bearing effect

[33:50] Which by the way in case it's not clear

[33:52] oil is only under pressure inside

[33:58] There's a whole bunch more of them too which I haven't covered

[34:00] inside the cylinder head to keep the camshafts lubricated

[34:03] as well as the moving parts of the valves.

[34:06] But once the oil makes its way out of whatever

[34:08] confined space it used to be in,

[34:10] it will just sort of ooze out.

[34:12] And then it's got to get back to the bottom of the engine

[34:15] so the oil pump can suck it up again.

[34:18] So there is also a series of pathways throughout the engine

[34:21] that will simply return any pooling oil to the bottom via gravity.

[34:25] And that's why internal combustion engines

[34:31] If I were to turn this engine upside down and try and operate it,

[34:34] or frankly, even on its side like it is now,

[34:37] oil would be pooling in places it shouldn't

[34:41] And so the lubrication system just...

[34:44] wouldn't work.

[34:46] And that's bad because everything

[34:53] If for whatever reason, the engine were to lose oil pressure,

[34:57] then suddenly you have a very big problem.

[35:00] That nice fluid bearing effect you get which keeps the metal parts from actually touching each other

[35:05] will go away and now... metal parts

[35:12] and that's going to produce a lot of friction,

[35:14] which will produce a lot of heat.

[35:16] And before long the engine will seize,

[35:19] meaning parts get fuzed together

[35:24] It is possible to get a seized engine unstuck,

[35:28] but it will definitely be damaged in some way

[35:30] and will likely have a greatly shortened lifespan.

[35:33] So you never, ever, ever, ever want to run an engine

[35:37] without knowing that there is sufficient

[35:42] And that is what that light is for.

[35:45] It's connected to a pressure switch

[35:50] In other words, when there is no oil pressure,

[35:53] that switch completes a circuit which lights up that light.

[35:57] This is what the pressure switch looks like.

[35:59] It's an unassuming little thing.

[36:01] Once the engine is turning,

[36:03] the oil pump will start forcing oil into all those passageways.

[36:07] And this port on the side is tapped off of those passages.

[36:11] So sufficient oil pressure will open this

[36:17] This design allows you to check that the pressure switch is actually functional,

[36:21] because if you simply turn the key without cranking the engine,

[36:25] you should see the oil pressure light.

[36:27] There's no oil pressure yet because the engine isn't running!

[36:30] But when you start the engine,

[36:32] that light should go out almost immediately.

[36:35] And if it doesn't, there's a problem.

[36:38] That problem isn't necessarily with the engine, of course.

[36:42] It could simply be a bad pressure switch.

[36:45] But that's a really risky assumption to make

[36:48] because if that light and the switch is working as it should,

[36:52] then if the light comes on, you are

[36:55] then running your engine without oil pressure, which will kill it.

[37:00] Oh, and fun fact eagle-eyed viewers

[37:04] may have noticed that this car had a bad pressure switch,

[37:07] but it failed open.

[37:09] The oil pressure light was never coming on

[37:11] even without the engine running.

[37:13] Here's me turning the key and that light is nowhere to be seen.

[37:18] This meant the car could never warn me that I've lost oil pressure,

[37:22] which isn't as bad as actually losing oil pressure,

[37:27] Luckily, I happened to buy this entire engine for making videos

[37:30] and it had its own oil pressure switch on there,

[37:33] so I just swapped them over.

[37:34] And now that light is actually doing its job.

[37:37] Quick side note,

[37:38] a lot of older cars didn't have an oil pressure warning light

[37:41] and instead had an oil pressure gauge,

[37:44] but that's mostly gone,

[37:49] Some new vehicles still have oil pressure gauges,

[37:52] but they're mainly found in big trucks

[37:54] because getting to see an engine oil pressure readout makes some people feel big and manly and important.

[38:01] But I mean, most people don't really care

[38:05] how much oil pressure an engine

[38:08] And without knowledge of how much is actually correct,

[38:11] a gauge isn't that useful anyway,

[38:13] and that's why a simple pressure switch

[38:17] "oil pressure is below a safe threshold," is frankly better.

[38:22] Yeah, I said it.

[38:24] Gearheads like to call these idiot lights

[38:26] because we used to expect people to know

[38:31] In fact, some cars in the past had a little yellow warning light

[38:34] which literally said "check gauges."

[38:37] But while I too lament the loss

[38:41] a little more about how their cars work than they seem to now,

[38:44] I think it's fair to say a warning light is all that's really needed,

[38:48] but you do need to know what that warning light means.

[38:52] On that note, why might you actually lose oil pressure?

[38:57] Well, it's very rare for it to suddenly just happen.

[39:02] I hope I haven't made it sound like this is something

[39:04] you need to be extremely vigilant about all the time,

[39:06] though you probably should watch the oil pressure

[39:12] and I'll explain that further in a moment.

[39:14] If you're just driving around on a normal day, though,

[39:17] it's extremely unlikely

[39:22] That would really only happen

[39:26] And given that it's literally the most lubricated part

[39:30] since it sits in oil and pumps it around,

[39:33] that's quite rare.

[39:35] It does happen, but it's extremely rare.

[39:38] However, if your engine burns oil,

[39:41] which it shouldn't, but it tends to start happening

[39:44] when an engine gets very old and worn out.

[39:47] Or if it wasn't designed very well,

[39:50] well then the amount of oil inside

[39:57] There's quite a good deal of margin for error,

[39:59] so losing a quart of oil between

[40:04] But if your engine burns through a lot of oil,

[40:08] then eventually the oil level can get low enough

[40:11] that the oil pump starts to have trouble

[40:16] If this is happening, the oil pressure

[40:22] That is not as bad as not having

[40:28] The bearings inside the engine

[40:32] and they're going to start wearing

[40:36] So you probably need to add some oil to your engine

[40:42] But the most common reason you might one day lose

[40:49] For example, you went in to get an oil change

[40:52] and the technician forgot to actually fill the engine

[40:54] with new oil after they drained the old oil out.

[40:57] Or maybe they forgot to put the drain plug back.

[41:00] Or perhaps they didn't tighten it enough

[41:01] and it backed itself out as you were driving

[41:04] and your car puked all of its oil onto the ground.

[41:07] To be clear,

[41:10] But seriously, after you get an oil change,

[41:13] pay attention to that light for a while.

[41:16] You really want to make sure it goes out quickly

[41:22] But speaking of oil changes,

[41:23] this car is due for one, so let's do it!

[41:26] Why not?

[41:27] In fact, I have no idea whether it's actually due for one.

[41:30] But that's kind of why I'm doing it.

[41:33] Changing your own oil is actually quite easy,

[41:36] but I don't really recommend it because it's messy,

[41:40] you have to deal with the old oil

[41:42] (and yes, parts stores will take

[41:46] And, it honestly hardly saves any money.

[41:49] But why don't I show you the process?

[41:52] Actually, first, if you don't know why you have to change the oil

[41:56] every some thousand miles or so, well, here's why:

[42:00] The oil gets really hot

[42:02] and the piston rings aren't perfect.

[42:05] Remember, there's a whole bunch of explosions going on in here!

[42:09] Several every second, just at idle!

[42:12] And the intense pressure inside the cylinders means

[42:15] some combustion byproducts are going to end up getting past the piston rings

[42:20] and into the crankcase where they'll mix

[42:26] That will eventually start to chemically break it down.

[42:29] And if that's not bad enough,

[42:31] the oil which clings to the cylinder walls gets extremely hot,

[42:35] which also causes chemical breakdown.

[42:37] Over time, this causes the oil to lose its lubricative properties,

[42:42] and that means your engine can start to wear.

[42:45] And if you're really overdue for an oil change,

[42:48] little bits of stuff can precipitate out

[42:50] of old engine oil and stick to things.

[42:53] That's engine sludge.

[42:55] And if it gets bad enough, it can start breaking things

[42:58] by plugging up those tiny oil passageways.

[43:01] So you gotta change your oil regularly to keep that from happening and to keep the engine healthy.

[43:08] I'm deliberately not commenting on how often

[43:13] But my basic advice is consult your owner's manual and maybe do it a little more often than it says you should.

[43:21] But I've got one of those

[43:25] How about that?

[43:26] But this one does.

[43:28] So first I'll get it up in the air a little bit.

[43:31] You don't need a lift to do this.

[43:33] If all you want to do is your own oil changes,

[43:35] you can purchase these ramps

[43:39] and that'll give you enough room to work with.

[43:42] There's two things you need access to from the bottom:

[43:45] the drain plug and the oil filter.

[43:47] Though in some cars the oil filter is somewhere else

[43:50] or possibly behind a cover of some sort.

[43:53] You'll also need something to catch

[43:58] And then of course, you'll need new oil and a replacement filter.

[44:02] Here's a five quart bottle of the cheapest oil I found in the store,

[44:06] because this car is not worth getting fancy over,

[44:08] and here's a replacement filter which fits the car.

[44:12] Speaking of the oil,

[44:13] your car's engine is going to call for a specific oil viscosity,

[44:17] which some people refer to as its weight.

[44:20] The Society of Automotive Engineers came up with a way to define motor oil viscosity

[44:25] using a simple numbering scheme, and bigger numbers are more viscous.

[44:29] This car needs 5W-30 motor oil.

[44:33] And the cool thing about that

[44:34] is that this oil has two different viscosity grades.

[44:38] When the oil is cold, it has

[44:43] That's the 5W, and the W is for winter.

[44:47] But when the oil is hot

[44:49] it has the viscosity of a 30 weight oil.

[44:53] Now any oil loses viscosity and gets thinner as it gets hotter.

[44:57] And this is no different.

[44:58] But as the engine warms up, additives in this formulation

[45:02] slow down that thinning process.

[45:05] And that's how when it's hot, it has the same viscosity

[45:08] as an unmodified 30 weight oil.

[45:11] This is actually a really neat thing we figured out how to do.

[45:14] And it means the engine has

[45:18] but still has the same protection

[45:23] Right. And the breakdown of those additives over time

[45:26] as the oil gets contaminated with combustion byproducts and whatnot, lowers the oil's viscosity grade.

[45:32] And that's yet another reason you need to change it periodically.

[45:36] So to do that, I'll start by draining the old oil from the engine.

[45:40] But first I'm going to remove the filler cap up top,

[45:43] which will allow that oil to leave the engine more quickly

[45:46] by breaking the vacuum and letting air into the top of the engine.

[45:50] Then I'll put the drain pan below the drain plug of the engine,

[45:54] but I'm going to position it off-center.

[45:56] You'll see why shortly.

[45:58] Quick note, the transmission will also have a drain plug,

[46:02] so make sure you know how to tell the engine and transmission apart before you drain the wrong thing.

[46:07] Next, I'll use a wrench to crack the drain plug loose.

[46:11] The engine is warmed up,

[46:14] with a gloved hand I'll then remove the plug.

[46:18] If you keep pressing in on it while you back it out,

[46:21] you can usually keep it from dripping any oil at all

[46:26] and then you can simply yoink it out

[46:31] And now that it's flowing out of there,

[46:33] you can see why I didn't center the drain pan.

[46:36] As the old oil flows out, we'll deal with the oil filter.

[46:40] This style of oil filter has built in threads

[46:47] Or in the case of this car,

[46:49] whatever you call this part,

[46:53] Anyway, these should only be put on hand tight,

[46:57] which means they should come off easily,

[47:00] but should is carrying a lot of weight there.

[47:03] And that's why I have this oil filter wrench.

[47:07] Once it starts coming loose, keep in mind

[47:09] this thing is filled with oil and will be gross.

[47:12] Many drain pans like this one have a spot

[47:15] molded into them to put the used filter and let it drain out.

[47:18] And now I'll take the new filter and with my gloved hand,

[47:22] I'll smear just a little bit of the old oil onto the gasket

[47:26] before screwing it onto the engine.

[47:28] And again, this should only go on hand tight.

[47:33] By the way, these claim to last long enough to only change the filter every other oil change.

[47:38] But these are like five bucks,

[47:41] Its job is to trap

[47:45] before they plug up all those little parts and stuff,

[47:48] which would be very bad.

[47:49] So I don't think it's worth risking it.

[47:51] Just replace it.

[47:53] By this point, the engine is probably almost done

[47:58] But if for some reason it's still flowing, let it flow.

[48:02] Once it's down to barely a trickle,

[48:07] Ideally, you'd replace this crush washer which seals that hole,

[48:11] but I did not get a replacement, so I will be reusing the old one

[48:15] Once I've started threading the plug by hand,

[48:18] I'll then reach for an impact wrench.

[48:20] Except I'm joking.

[48:21] Don't ever use power tools for this.

[48:24] If you screw up the threads on the oil pan,

[48:26] this oil change went from an easy job to a very bad day.

[48:30] So only use hand tools when dealing with drain plugs.

[48:35] I even looked up the torque spec for this guy.

[48:37] It's 34.3 Newton meters or 25 pound feet.

[48:42] And I used this old torque wrench which I have

[48:46] but hey.

[48:47] It's the thought that counts.

[48:48] [click]

[48:50] And now we're done down here.

[48:52] But we're very much not done done

[48:58] Well, it probably has about half a quart stuck in there

[49:01] this one made when getting some of this footage,

[49:04] but it's definitely not enough for it to run without damage.

[49:07] If I were to start it now, that would be very bad.

[49:10] Oh, fun fact, did you know engines are dishwasher safe?

[49:13] The dishwasher would not agree, but, uh,

[49:16] it did clean it.

[49:18] Anyway,

[49:19] now we have to put new oil into the engine,

[49:21] which is done via the filler cap.

[49:24] This is literally just a big hole that leads into the timing cover.

[49:28] Look, you can even see the timing chain a little bit.

[49:31] Pour new oil into here and it will fall down into the oil pan...

[49:35] or whatever this is- let's just call it the oil sump.

[49:39] However, this car will not need this entire bottle of oil.

[49:43] In fact, it would be overfilled if I put the whole thing in

[49:46] and an engine with too much oil is also a problem.

[49:51] So I'll put most of it in there,

[49:53] but then I'll have to check how much oil is inside using the dipstick.

[49:57] Which is literally just a stick in a tube.

[50:00] And that tube leads to the engine's oil sump.

[50:03] The stick has markings on the end,

[50:05] and once you've cleaned it using a rag or paper towel or whatever,

[50:08] you'll stick it down into the tube

[50:13] The tip of the stick should have poked down into the oil,

[50:16] and you'll be able to see the oil level when you pull it out.

[50:19] If you're not seeing any oil towards the markings,

[50:22] you're probably still about a quart shy

[50:27] Just keep adding a little bit at a time, though,

[50:31] and eventually you'll start to see the oil in the range.

[50:34] I'm going to shoot for just below the full mark,

[50:37] which will account for any oil

[50:39] which might be sticking to the timing chain and junk.

[50:42] And once it's full,

[50:44] well that's an oil change.

[50:46] It's really quite straightforward.

[50:48] Now all that's left to do besides dealing

[50:53] is to put the oil cap back on and start the engine.

[50:56] But now a note on prefilling the oil filter.

[51:01] Some people insist that you should fill the oil filter

[51:04] with clean oil before putting it on to the engine.

[51:07] The theory is that this oil filter

[51:12] and so when I start the engine,

[51:14] there will be a brief moment

[51:19] But personally, I think this is a very silly thing to obsess over.

[51:24] Why?

[51:25] Well, because not only is the oil filter filled with air right now,

[51:27] but so is every single one of the passageways inside the engine.

[51:31] So forgive me for not thinking

[51:33] filling this with oil is going to make a huge difference.

[51:37] Granted, this engine has a tiny little filter

[51:41] But why don't we take a look at how quickly

[51:43] that oil pressure light goes out once I start the engine?

[51:47] Okay.

[51:47] I just changed the oil.

[51:48] Let's crank it up.

[51:50] [engine starts]

[51:54] Yeah.

[51:55] What, one second?

[51:58] One extra second.

[51:59] It's not a big deal.

[52:01] I mean, you go ahead and fill these things with oil if you want to,

[52:04] but I feel like doing that is just creating

[52:10] The film of old oil that's sticking to the bearings, etc.

[52:13] is going to be enough to prevent damage in the 2 or 3 seconds

[52:17] it takes the oil pump to fill even a really big oil filter.

[52:21] Regardless, now that the engine is running, it's prudent to check the oil filter and drain plug for any signs of leaks.

[52:29] And assuming there are none,

[52:31] you're done!

[52:32] We've looked at a great deal of stuff today,

[52:34] but we've just been looking at

[52:39] Yeah, there are a whole lot of spinny bits in there,

[52:42] and they all need lots of lube to keep on spinning,

[52:45] but they don't start spinning unless

[52:50] For instance, we need to deliver

[52:54] and we need to ignite that fuel with a spark plug.

[52:58] We use a computer to do those things,

[53:00] and we've been doing that for decades now.

[53:02] But the computer needs to know

[53:05] precisely where each part of this engine is,

[53:08] so it can tell when it should do those things.

[53:12] In the next video on

[53:17] well, that part, the management part,

[53:20] because while this is a very intricate

[53:24] it is literally useless without the digital system

[53:28] which controls the spark plugs, the fuel injectors

[53:31] and even the intake valve timing.

[53:34] I'll be covering all of that in the next video in this series,

[53:37] so stay tuned.

[53:40] ♫ load-bearingly smooth jazz ♫

[53:43] [whirring sound is increasing in speed]

[53:45] [schwoop]

[53:46] [banging]

[53:47] [comically metallic crash]

[53:48] It's fine!

[53:50] It's fine.

[53:51] Nothing happened.

[53:52] It just fell off the table.

[53:54] It's fine.

[53:56] This is the crank pulley and it provides power for the engine accessories.

[54:02] That's not working.

[54:04] and it provides power for engine accessories such as the alternator,

[54:08] the air conditioning compressor...

[54:12] I thought you would behave a little better.

[54:13] You didn't. You didn't.

[54:16] [oh no here we go again]

[54:20] [the sounds weren't as funny this time]

[54:23] It's fine.

[54:24] Nothing happened.

[54:26] It's fine.

[54:28] So now I guess I need to start plotting my atonement for the bearing/journal decision.

[54:33] Does one plot an atonement?

[54:35] Well that's not important right now.

[54:36] What is important is that you imagine the animated character Doug Funnie writing in his bearing.

[54:43] For some of you, that hurt.