Avoid Getting Ripped Off - What is a Blown Head Gasket, Leaking Valve Cover Gasket, How to tell


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


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


and finally if the head gasket blows it

can leak internally to the engine but


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