Understanding of the Head Gasket
As an auto repair professional, one of our daily challenges
is Communication. In this article I want to explain why we
ask, what we ask, to answer the question, Do you have a
Head Gasket problem?
Have you lost any engine coolant? Caution! Check with
engine cool. If the engine coolant is low for any reason,
you can have many of the same symptoms as a head
gasket failure. We have to eliminate other areas of coolant
loss before trouble-shooting the head gasket.
Is your temperature light or gauge operating normally,
and has it been? If your temp gauge hasn't worked in two
years, you might want to say so. If the temp is suddenly
high, then we know that the problem is new. You should
note that the temperature gauge works with coolant so,
again we have to check that first.
Does your passenger compartment heat work properly?
Sometimes this is the first indicator the vehicle driver
senses. Again works on coolant check level first.
Has your vehicle “boiled over” or “overheat”. I recommend
getting help before this point but if you have not, this is a
good indicator of a coolant related problem.
Is there white smoke coming from your exhaust? This will
be persistent and not that cold weather smoke that we
see. This could be a sign of coolant getting into the
cylinders and out the exhaust. You may also detect a
sweet smell with this.
Does the engine seem to run normally, or does it have a
“skip” or “misfire”. If coolant is entering a cylinder it will
not work correctly, you may feel a jerking or unevenness
to the motor.
Do you have any external leaks directly from the head
gasket? The head gasket can generally develop one of
three leaks.
A: Coolant, either externally or internally.
B: Oil, externally, or on the right engine, into the coolant.
B: Combustion, this is most likely between two cylinders.
Now I will tie this all together. Most of the questions that I
ask are coolant related. A leak between the combustion
chamber and the coolant, is the end result of most head
gasket failure.
There is a large difference of operating pressures of the
two systems. The coolant system operates around 15PSI.
And the combustion chamber build up over 130PSI and
then has an explosion take place, then develops a vacuum
and does this around four hundred times a minute, at idle.
Coolant circulation is key to transferring heat from the
engine to the radiator and to the heater core. Circulation
is dependent on a low-pressure area and a high-pressure
area. In a normally operating system the water pump
creates this. A leak between the coolant and combustion
will act like an air pump and raise the pressure of the
entire cooling system. You no longer have the pressure
differential to create flow, you have no passenger
compartment heat, and you have no engine cooling.
If not caught at this point, then we get the “over heating“
and “boiling over”, which is the system built for 15PSI
relieving some excess pressure. The radiator cap is
designed with a pressure relief built in. If the cooling
system reaches the relief pressure the cap lets off steam,
unless you have another part of the system that is weak
and gives out before the cap.
The most common weakness is the hoses. If you have a
radiator hose or heater hose failure, it doesn't mean you
have a head gasket problem, but it means you might have.
The “smoking” and “skipping” usually show up after
restarting the engine. When the engine is off there is no
pressure in the combustion chamber, the cooling system
is now the dominant force and pushes coolant into the
cylinder. When you restart the engine that cylinder won’t
fire and you will pump the coolant into the exhaust. At
this point it’s pretty easy to figure out!
As mentioned earlier, there are two other common leaks
associated with the head gasket. Some engines have oil,
under pressure, flowing to the head, usually to the
camshaft. This oil must pass through and be contained by
the head gasket. Most of the head gasket related oil leaks
that I deal with are external. I have seen oil get into the
cooling system, however not often.
The head gasket also has to seal between the cylinders.
You have an environment with extreme heat and high
pressure right next door to another one, If the smallest
leak develops between them, they start exchanging gases.
This will act like a torch and quickly burn out the gasket.
With this type of failure you will sense a lack of power and
rough running. Because this usually happens in an area
were there is no coolant, you will not have the symptoms
of the combustion-coolant leak.
Carlton Wrench
As an auto repair professional, one of our daily challenges
is Communication. In this article I want to explain why we
ask, what we ask, to answer the question, Do you have a
Head Gasket problem?
Have you lost any engine coolant? Caution! Check with
engine cool. If the engine coolant is low for any reason,
you can have many of the same symptoms as a head
gasket failure. We have to eliminate other areas of coolant
loss before trouble-shooting the head gasket.
Is your temperature light or gauge operating normally,
and has it been? If your temp gauge hasn't worked in two
years, you might want to say so. If the temp is suddenly
high, then we know that the problem is new. You should
note that the temperature gauge works with coolant so,
again we have to check that first.
Does your passenger compartment heat work properly?
Sometimes this is the first indicator the vehicle driver
senses. Again works on coolant check level first.
Has your vehicle “boiled over” or “overheat”. I recommend
getting help before this point but if you have not, this is a
good indicator of a coolant related problem.
Is there white smoke coming from your exhaust? This will
be persistent and not that cold weather smoke that we
see. This could be a sign of coolant getting into the
cylinders and out the exhaust. You may also detect a
sweet smell with this.
Does the engine seem to run normally, or does it have a
“skip” or “misfire”. If coolant is entering a cylinder it will
not work correctly, you may feel a jerking or unevenness
to the motor.
Do you have any external leaks directly from the head
gasket? The head gasket can generally develop one of
three leaks.
A: Coolant, either externally or internally.
B: Oil, externally, or on the right engine, into the coolant.
B: Combustion, this is most likely between two cylinders.
Now I will tie this all together. Most of the questions that I
ask are coolant related. A leak between the combustion
chamber and the coolant, is the end result of most head
gasket failure.
There is a large difference of operating pressures of the
two systems. The coolant system operates around 15PSI.
And the combustion chamber build up over 130PSI and
then has an explosion take place, then develops a vacuum
and does this around four hundred times a minute, at idle.
Coolant circulation is key to transferring heat from the
engine to the radiator and to the heater core. Circulation
is dependent on a low-pressure area and a high-pressure
area. In a normally operating system the water pump
creates this. A leak between the coolant and combustion
will act like an air pump and raise the pressure of the
entire cooling system. You no longer have the pressure
differential to create flow, you have no passenger
compartment heat, and you have no engine cooling.
If not caught at this point, then we get the “over heating“
and “boiling over”, which is the system built for 15PSI
relieving some excess pressure. The radiator cap is
designed with a pressure relief built in. If the cooling
system reaches the relief pressure the cap lets off steam,
unless you have another part of the system that is weak
and gives out before the cap.
The most common weakness is the hoses. If you have a
radiator hose or heater hose failure, it doesn't mean you
have a head gasket problem, but it means you might have.
The “smoking” and “skipping” usually show up after
restarting the engine. When the engine is off there is no
pressure in the combustion chamber, the cooling system
is now the dominant force and pushes coolant into the
cylinder. When you restart the engine that cylinder won’t
fire and you will pump the coolant into the exhaust. At
this point it’s pretty easy to figure out!
As mentioned earlier, there are two other common leaks
associated with the head gasket. Some engines have oil,
under pressure, flowing to the head, usually to the
camshaft. This oil must pass through and be contained by
the head gasket. Most of the head gasket related oil leaks
that I deal with are external. I have seen oil get into the
cooling system, however not often.
The head gasket also has to seal between the cylinders.
You have an environment with extreme heat and high
pressure right next door to another one, If the smallest
leak develops between them, they start exchanging gases.
This will act like a torch and quickly burn out the gasket.
With this type of failure you will sense a lack of power and
rough running. Because this usually happens in an area
were there is no coolant, you will not have the symptoms
of the combustion-coolant leak.
Carlton Wrench
Head Gasket
Failure
at this point its easy
to figure out.
Failure
at this point its easy
to figure out.
MrWrench.com
The online home of
Wrench's village auto
service
The online home of
Wrench's village auto
service
