Where is the head gasket
Avoid Getting Ripped Off - What is a Blown Head Gasket, Leaking Valve Cover Gasket, How to tell
[Music]
everyone local beach garage well this is
another video in this series on how not
to get ripped off when you need to get
your car fixed so you have a problem
with your car and somehow it ends up at
a dealership or a mechanic's told
whatever you drove it there if you're
having problems or you went for an
inspection whatever and they come out
and say the dred it works to you oh you
have a blown head gasket you need new
head gaskets the question is how do they
know you have a blown head gasket and do
you really need one in order to ask
those questions it's important for you
to understand what a head gasket is what
it does what are the possible symptoms
so when they tell you what's happening
you will know whether or not that
symptom is a head gasket and finally
what's the difference between a head
gasket and a valve cover gasket knowing
these simple things will help you when
you go to your car fixed to know whether
or not they're telling you the truth so
let's get started all right so let's
talk about the basics of what's inside
the engine then we can talk about the
head gasket the cylinder head and your
valve cover gasket whether you have a
four cylinder like this would be a four
cylinder here but this is actually v8
because there's another cylinder down
here they're all the internals are gonna
be very very similar you're gonna have
pistons the block the cylinder head and
the gasket between them now this is what
happens you have the air and the
gasoline or whatever goes into the
cylinder and as the cylinder head I'm
sorry as the piston as the piston comes
to the top like this when it gets to the
top the spark plug fires the gas and the
air burn and as that expands that's what
pushes the piston down in the combustion
chamber or in the in the cylinder here
that's what pushes the piston down
that's what makes your crankshaft rotate
and cause your wheel a drive through the
transmission then when the piston comes
back up after rotation this is what
pushes out all the exec of the exhaust
gasses so all the exhaust gas comes up
the top it goes out your exhaust and
ya'll exhaust manifold out your exhaust
pipe all the way out to the backyard car
so that's how the inside of the engine
works and in a very basic basic form now
you have the cylinder block you have
your pistons and if you notice there's
these little passageways in here and
this is where your antifreeze or your
coolant flows the coolant flows through
these passageways into the cylinder head
it returns and it goes back to your
radiator cools down comes back to your
water pump it pumps through so coolant
is always being pumped through your
engine that's what keeps it cool so you
have this part of your engine which is
all the heat and the combustion where
all the action happens then you have to
put your cylinder head on before you put
your cylinder head on you have to have a
head gasket and this is what a head
gasket looks like they're all very very
similar they may be different colors it
may be all metal there may be different
you might have a five cylinder or six
alone or whatever but they're all very
similar and what the head gasket does is
it seals the block between the block and
the cylinder head so that's what a head
gasket does it seals between the block
and the cylinder head that's not all it
does though if you notice these coolant
passages are large but the hole that
mates up with the passageway here the
slot here and the head gasket is not as
large it's a different shape that
restricts the coolant flow because you
don't want too much cool and flow
through because you'll cool the cylinder
head faster than the block and that will
cause a problem with the second reason
you have a gasket the head gasket also
accounts for difference in expansion if
you have a cast-iron block with an
aluminum cylinder head the aluminum
cylinder head is going to expand at a
different rate and it's going it could
potentially cause a leak and you don't
want to leak so the gasket also accounts
for leakage and expansion it also
accounts for any unevenness so if you
look at the the block here the the
machine marks if there's a little nick
in there or on the cylinder head if
there's little
perfection the gasket makes up for those
little imperfections that's the only
thing that the head gasket does now if
you can imagine you have all these
cylinders here they're firing a gas an
air burning in here and you got heat
here and get pretty hot at higher rpm so
you get up to 1,100 degrees up here so
when you have a head gasket on here what
can happen is the area between these
cylinder walls can start to wear and
between the cylinder walls if it eats
way here one cylinder can leak in the
other cylinder and if that happens the
failure mode is the engine will run real
rough you'll have trouble you'll
probably get an error code Check Engine
something will happen that's when you
have a head gasket failure that's
leaking from one similar to the other
okay
the next way can leak is it can blow a
head gasket right out the side so it can
leak from the combustion chamber to the
outside of the engine it might leak into
the top bottom but if that happens where
there's a let's say we're to leak right
here if this head gasket were to leak
right here you would see exhaust gasses
all around this side of the engine so if
someone says you have a blown head
gasket and it's leaking to the outside
you better look for all that burnt or
black soot around where the gasket would
be leaking the other way that head
gasket can leak it can leak from the
combustion chamber into the coolant
passage okay so you have cool of the
combustion chamber here of the cylinder
and here's a coolant passage over time
some antifreeze or some coolant can
become acidic and when that happens it
can slowly eat away at this metal ring
in here and eat through the paper and
start to leak into the coolant when that
happens that's when you start to have
coolant you're getting in your cylinder
it'll get in here and burn you'll have
white smoke on your tail pipe or oil
from the cylinder will get in your oil
and your coolant will start to turn
milky brown it will look real milky so
that's how you know you're still it's
the cylinder head gasket is leaking from
the combustion chamber into your coolant
okay
and finally if the head gasket blows it
can leak internally to the engine but
regarde
of where it blows and where it's leaking
you'll have different symptoms the
easiest one obviously is if it's leaking
from the cylinder combustion chamber
into the coolant passage you're gonna
have either milky fluid you're gonna
have milky oil in the bottom of the
engine because the coolant will get in
here and get into your oil that you oil
be milky you'll have milky coolant or
when you when the engine is running the
overflow tank inside your car engine
compartment will be bubbling there the
pressure inside these cylinders can get
up to 150 160 psi a lot of pressure so
as that pressure comes up here it's
going to force its way into the coolant
system and the coolant system is only
supposed to be around 8 to 15 pounds so
the pressure goes in here it pressurizes
your coolant system and when you open up
the cylinder or when you open up your
hood you look in the engine compartment
you see bubbling and your coolant and
you think the engine is overheating but
that's not what's happening what's
happening as your coolant is being
pressurized causing it to bubble okay so
now we have a head gasket there that's
how you know how the head gasket is
really leaking now if you have mostly
most likely if you have a newer engine
with fuel injection and if the if you
want an easy way to check is to just
take out having to take out the
thermostat and they can drain the
coolant and you can start the engine for
a couple seconds and you can smell
around where the thermostat is and then
the intake manifold and if you smell
gasoline or if you smell exhaust
anything like that then you know the
head gasket is blown it's leaking from
the combustion chamber into the coolant
passage if it's leaking to the outside
you look for the black suck if it's
leaking from one to the other you do a
leak test and what they can do is they
can put in the cylinder head where the
spark plugs are you can put a gauge in
there pump this up full of pressure and
see if it leaks if it's if it doesn't
leaking from one similar to another is
it leaking out the side or is it not
leaking at all so it's they can do some
it's called a leak down test so if they
say you have a blown head gasket ask
them to say where is it blown how is it
how is it blowing is it leaking from the
combustion to the coolant is it leaking
to the outside or is a cylinder to sell
either way they should be able to do
something called a leak down test and
that's when they hook up a pressure
gauge to the spark plug hole they've
turned the engine over several several
times and they see how much pressure can
be held inside of a combustion chamber
okay now we have our gasket here and on
top of that is a solder net cylinder
heads are pretty heavy and here's our
cylinder head now the cylinder head sits
under you can see why it's called a head
gasket it goes between the cylinder head
and the block blow and head yeah so
you're gonna see it all over the place
okay and here's your cylinder head this
or all the valves are these this is
where the intake comes in so your fuel
and air coming here goes in through the
valve gets burnt and then it comes out
the other side to the exhaust on top
here is where your oil lubricates the
valves and the stems and the seal so you
get lubrication up here when you take
the valve cover off all you've seen here
is oil if you take the valve cover off
and you see coolant in here then you
might have a blown head gasket or you
could have a cracked head there's a lot
of ways to check to see what it really
is but at least we know what we're
looking for with a head gasket here's
your cylinder head on top of your
cylinder head will be a valve cover
gasket very similar to this one and
these just sit on top and the only thing
this gasket does is seals oil from
leaking in a cylinder head to the
outside of the engine so if you open
your hood and you look at the valve
cover and here's the valve cover is
called a valve cover simply because it
covers the valves the valve cover goes
on top just like this if you take the if
you go into the shop and if they take
off the valve cover and you see coolant
in there there's a problem okay if the
valve cover is sitting here and you see
engine oil just dripping down or
dripping down around the outside of the
valve cover all you really need to do in
that case is change your valve cover
gasket that's a very easy job it
shouldn't take that month much maybe
depending on where you go my only take
2530 dollars sometimes they are
expensive it can be 50 60 bucks to get a
valve cover gasket change but that's
what a valve cover gasket is you take
the valve cover off
then you see your valve cover gasket
there and it's been a good shape
that's not leaking you're good there
then you can ask them to take off the
cylinder head and when they take off the
cylinder head you can look inside you
can look inside and just take a look at
the gasket and have them show you where
it's leaking if it's not leaking
anywhere if there's no evidence of it
leaking if they can't show you where
it's leaking you did not need a head
gasket okay very basics cylinders block
head gasket cylinder head goes on top
then we have our valve cover gasket like
that and then our valve cover very
simple so there you have it now you know
what kind of questions to ask if someone
says you have a blown head gasket ask
them to show you your they're gonna have
milky white oil the oil will be milky
they'll be oil in the coolant the
coolant we brown or they'll be leaking
somewhere there should be a burnt mark
on the outside of the engine or you
should really push them to do a leak
down test to show you that one cylinder
is leaking into the other cylinders it's
it's it's not that difficult and I hope
I was able to show you what the parts do
at least you understand what's going on
in there so if you do have to question
someone you're speaking with a little
bit of knowledge and a little confidence
so you don't get ripped off for a
cylinder head gasket because it can cost
$1,200 to change the cylinder head
gasket maybe even more depending on the
vehicle set of head gaskets might cause
1,500 $1,800 maybe up to 2,000 depending
on the vehicle so you want to make sure
that they're telling you the truth and
that you know and you get to see the
failure before you let them do the work
I hope that helps you and I have a lot
more tips coming up so stick around stay
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thanks for stopping by Pete's garage
