(grunting) - We're gonna start building the engine and we'll start with the engine block. It's also called the cylinder
block or just the block. We'll call it just the
block for simplicity. So the block, it's a huge
part, it's the biggest part of the engine. It's usually made of cast
iron or cast aluminum, increasingly aluminum lately. The block has, it's main function is
to house the cylinders and the cylinders is where
the piston slides up and down. So that's the primary
purpose of the block. It also incorporates
passageways for the coolant and for the oil. So the coolant circulates around
the cylinders keeping them cool because they get very hot
during the combustion process and oil circulates through the
block to the various places it's needed on the engine. The other purpose of the
engine block is it holds the accessories or the auxiliary
components for the engine, things like the
alternator, the water pump, the starter motor, the AC compressor. All of those components
generally mount to the block because it's good and strong
and it can take the weight. This engine block is made
from cast iron which has been the predominant method of
manufacturing engine blocks for the last 100 years or so. And the very first engines,
very early engines, used individual components,
individual cylinders, and a network of brass
pipes for oil and coolant, very steam pump looking engines. But those were extremely
hard to mass produce, very expensive to make. So when mass production came
along, casting engine blocks which incorporate the
cylinders, the oil passages, the main saddles for the crankshaft. All of those made it cheaper
to mass produce engines. So for a long time, engines
were cast from cast iron and if you take a look at the
surface of an engine block, it's rough and that's the
texture of the sand that's inside the molds from which
this engine block was formed. In the last 20 or 30 years,
it's become much more common for production engines
to have an engine block that's made from aluminum
alloy with magnesium or some other alloy. The reason is those are much lighter. So an aluminum block weighs
about 30 percent the same block in cast iron. So massive weight saving. So manufacturers who are
looking to achieve fuel economy or performance, an aluminum
block is the way to go. There's one other type
of engine block which is a billet's block which
you would only really find in a one off in the racing
world or for restoration. And this is where a block of
aluminum is taken, or just a solid block and the engine
block is milled out of that block with all the metal
that's not needed basically machined away or drilled
out using a milling machine. That's very expensive to do
so you're only really gonna find that in the performance world but in production engines,
cast iron, cast aluminum alloy, that's what your engine block's made of. Once the engine's been cast,
it's got this rough finish that you see on the unfinished edges. Then it's machined on the
surfaces which are important which join to other parts or
for example on the cylinders, those parts need to be machined to make them perfectly smooth. I've put the engine on a
stand and rotated it round so that we can see the top
surface and the cylinders. The cylinders are made in a block. If it's a cast iron block, then
they'll be machined directly into the block. If it's aluminum alloy, then
it's likely that there will be holes bored and then cylinder
liners will be inserted or those cylinder liners will
be inserted into the mold and then as the aluminum is
poured into the mold, it bonds to them and that contains the liners. With aluminum alloy,
there's another option which is a chemical
coating which is applied to the cylinders. Nikasil is one name. And that has a similar
function to a liner. The reason that liners
are used on aluminum is that cast iron is a tough
metal which can take the wear and strain on these cylinders. Aluminum is much softer
and so a cast iron liner will be inserted. And you might also find cast
iron liners that are used to repair problems with cylinders. Let's take a look at the
surface inside these cylinders. On the surface on a cylinder
is vital because the piston moves up and down. We want minimal friction
and the piston must run on a film of oil. We don't want the piston rings
to contact the cylinder wall at all. Now on one hand, we want the cylinder wall to be perfectly smooth
to minimize friction. On the other hand, if it's too smooth then the oil simply falls off the walls. So we need a fine grain in
there to provide some sort of grip for the oil. So what you'll find is
there's a crosshatch pattern inside a cylinder on the walls
which is formed by a process called honing. And really, we want this 60
degree cross over of lines on the wall there to form
a very fine diamond shape with indentations that
can form pools of oil on which the piston rings can run. I've rotated the engine around again. This top surface is called the deck. This is the surface that meets to the bottom of the cylinder head. In between this and the cylinder
head, there'll be a gasket. Here's the old gasket from this engine. So that sits there and it's
the gasket that forms a seal between these two surfaces. So it's important, it is vital that the
deck is perfectly flat so that we've got a gas-tight
seal because the top here, this is essentially
the combustion chamber. There's enormous gas
pressure inside this cylinder at the top and the head
gasket takes the brunt of that pressure. So the head gasket it can conform slightly to an uneven surface but the
top surface here needs to be perfectly flat and the
underside of the cylinder head also needs to be perfectly flat. Now, the engine block is
so massive and so tough that it's unlikely to warp. The cylinder head sometimes
can warp and this surface will need to be machined
down to make it flat again but the deck of the
block, that's much tougher and is less likely to need machining. Now, for an inline-four and
inline-six engine there's just a single deck but if you've
got a v-shaped engine or a w-shaped engine then
there's multiple decks. There's one deck for each
cylinder head and if they need to be machined then they
all need to be machined to the same height. Inside the block run oil passageways which are called galleries. A lot of people call them galleys but that's completely the wrong word. A galley is the kitchen on a ship. So these are galleries and what happens is we have an oil pump here on the front ... I don't wanna go too much
into the lubrication system because we're gonna talk
about that in another video, but we need to roughly
understand how this works. So the oil pump is going
to pump oil out of the sump down here, up a pipe and then in here, which is the feed pipe
into the engine block. The oil's gonna run along here. It comes to the outside of
the oil filter, works its way through the filter, goes
through the inside of the filter and then into here which
is a drilled out passageway which runs all the way
through the block here, it enters here and it
goes all the way through and then leaves here. And this main gallery here
is the main supply of oil to the rest of the engine. So from this main gallery, we
also have a gallery that runs up here and out through
a hole here in the deck which goes up to the
cylinder head and lubricates the camshaft and the valvetrain. And on there, there's
an oil pressure switch. In this case, it's just a
switch which is triggered by low oil pressure and
flashes on a warning lights on your dashboard. More advanced engines, you'll
find a pressure sensor. So, that's the main oil
gallery and from here we have a little oil passageways
which we can show you which run down to the main journals and to the jets which lubricate
the inside of the cylinders. So if we take a look at the
deck, the oil comes up here through this gallery and then
we've got a oil regulator here which a narrow hole
which keeps the pressure in the block nice and high, low down. It's a constricted hole. It's hard for the oil to get
through so that maintains the pressure down here but
that also supplies the oil that's needed to the cylinder
head and then once it's been used in the cylinder head,
it makes it's way back down through the block through these
return pipes which basically just drop the oil back down into the sump and it makes its way around again. So that inside the engine
block itself, the lubrication mainly happens on the underside. So I'll rotate this around
and we'll take a look at the underside. Having brought the
engine block round here, we can see the underside. So the engine's upside
down basically here. And what we've got is we've
got these main saddles which is where the crankshaft sits. It's vital that these get
a good supply of lubricant because the oil not only
works here in this bearing but it also works its way
through the crankshaft which we'll see later. Anyway, there's holes drilled
from here down through into this main gallery
here, so the oil comes from the main gallery
out through these holes where it pumps into these bearings. We've also got on this engine, which is quite an unusual feature for a fairly standard engine like this, is we have jets which
receive a flow of oil and spray that oil onto
the underside of the piston and that lubricates the wrist pin of the piston or the gudgeon pin and it also keeps the piston cold and lubricates the cylinder walls. In other engines, you'll find
that as the crank shaft spins, I know we're upside down here
so it's hard to visualize, but the sump would be here
and the oil would be sitting in there, the crank shaft
would be spinning and that oil gets flung up and coats all
the inside of the engine. That is what we want. We want the inside of the engine to get a good coating of oil. These jets on this engine,
they help that process. I think what we'll do,
let's put the first parts onto this engine block and
we'll bolt on these jets that sit here and lubricate the inside of the cylinders. So we're gonna install these jets. There's four of them, one for
each cylinder and they've got a little locating pin in there. So we'll just drop that in and I believe there were
supposed to be brass washers but certainly no sign of any
brass washers when these came off the engine. In any case, we're only going to
end up with oil leaking where it's supposed to be anyway. So, let's drop that in
there and I'll find out the torque specifications for these. So you can see here this oil
jet sprays onto the inside wall of the cylinder and to the
underside of the piston. So we'll just tighten
this down, hand tight, and then torque it down with a torque wrench. So I'll just install the other three jets, one for each cylinder. So, what we've got here
is this is the engine. It's upside down and the crankshaft sits inside this bottom area of the engine block
and this bottom area that holds the crankshaft
is called the crankcase. So the other thing that's
interesting about the engine block is that these main caps,
there's five on here, that clump the crankshaft into the
saddles and hold the bearings inside, it's essential that
these have a perfect circle, perfectly round, perfectly
dimensioned bore on the center. And these are cast as part
of the block and then bored through, all the way through the block, all the way through all five of these. And then they're cut off
and machined on the ends. At least, that's my
understanding of it anyway. And so what you need to be
careful of is that these go back onto the right places because
they're actually formed as part of each one of these saddles. So the main caps needs to go back on in their original places and
generally they're numbered but if they're not clearly
numbered, you want to mark them with a dot or stamped marks in some way. (hammering) We've popped that back off for now. The other thing that goes on
the underside of the engine, don't forget we're upside
down here, is the sump or the oil pan which fits
on here just about there, lines up with its holes and holds the oil. And we'll talk about this
later but just for now that's another thing that
mounts to the engine block. And on the underside,
you may find a gasket. On this engine, we just
have an instant gasket, some form of instantly
cast adhesive gasket. So that's that. Let's turn the engine back over and talk about the core plugs. On this side of the block,
we've got some plugs. These holes, which are plugged, these plugs are called core plugs. Now, a lot of people
call these freeze plugs. They're commonly called freeze
plugs or expansion plugs and you'll find them in
parts catalogs in places listed as that. They have nothing to
do with freezing really and it's a common misconception
really that if the coolant inside the block freezes
then these plugs are designed to pop out. Maybe that would happen
if the coolant froze but realistically you're gonna
still suffer some serious problems most likely and the
block may well still crack. However, freeze plugs,
expansion plugs, that's kind of what they're known as,
but core plugs is what we're gonna call them because
that is what they are. And the reason that they exist
in the first place is that when the engine is cast
using these sand molds, molds are inside and the
block forms around that mold and there needs to be some
way to get the sand out of the block and that's what
these holes are used for. The engine is kind of tipped
up and the sand is emptied out and washed out and that
leaves us with these spaces inside here for the coolant to run. But the remnant of that is these holes which are then plugged with
these thin metal core plugs. I like to think that
when this casting process was first developed, some factory
somewhere a couple of guys were working there and they
produced this and they said, "Whoa, what about these ugly holes? "What are these?" and someone thought, these are not a bug, these are a feature. If anyone asks, that's in
case the engine freezes, the coolant will expand and
the plugs will come out. We'll call them freeze plugs. That in my mind is how they ended up being called freeze plugs
but that's the way they are. They're a little different
from the oil gallery plugs. If you look at the end of the
engine here, you can see we've also got a plug here. This one's for the oil gallery,
so oil gallery plugs tend to be small and on oil
galleries and core plugs will be bigger and all over the place. The other thing to note is
that these are thin metal. This block is good solid
cast iron or cast aluminum. But these core plugs can corrode and so it could be a
common place for leaks. If your engine block is
leaking, it's more than likely the core plug rather than
a crack in the block. Luckily, because they're
fairly easy to replace and they're roughly
standard sizes as well. While we've got the block round
in this position, let's talk about the engine mount which
on this car, mounts to these one, two, three bolt holes in the block. The block's a good place
to mount the engine to the chassis. It's super strong. It can definitely take the strain. So on here bolts an engine mount and that has a rubber mounting
which reduces vibration between the engine and the vehicle body. There's various other holes
and mounting holes here. These are called bosses where
the surface is machined flat to create a nice flush finish
and the hole is tapped out to give a thread to mount things to. So things like the water
pump, the alternator, the air conditioning
pump, anything like that is gonna be mounted to the block and it's good strong component. The other function of the engine block is to provide the cavities for the coolant to circulate and cool the cylinders. The reason we need to keep
the cylinders cool is because if they get too hot, then
the mix of fuel and air can pre-ignite, that
is, it can ignite itself before we want it to,
before we create the spark. That causes all sorts of
problems with timing and stress on the engine components. So it's something we really want to avoid. The other reason is generally
when parts become too hot or generally when they
become hot, they expand and that increases wear. So we want to maintain the
clearance between the piston and the cylinder wall. And if the cylinder becomes
too hot, the piston expands and we can have metal
to metal contact inside, which we want to avoid. So, we're gonna circulate
coolant around the cylinders through these voids and that
generally it's going to flow from the bottom up or upwards. Hot liquids rise above cool ones. So the general flow of
coolant you'll find will be from the block of the engine
up into the head and then away either from the front
or the back depending on the flow arrangement and back
around through the radiator. A well-designed coolant system
should have no air gaps, no voids inside that the
coolant can get trapped because when you drain the
coolant system, you want to drain all the coolant, you don't
want to find little reservoirs of coolant left in there. So that's one thing. It's a similar situation
with the oil passages.
This is a good overview of what an engine block is and does. I even learned a couple things I didn't know.
TIL about core plugs
I started watching the video and thought to myself "That looks quite a bit like a miata block".
Today I learned there is a channel detailing how every single part of a miata works. I can't wait to watch all these!