Coolant leaks must be found to prevent engine damage
Engine coolant is used to help keep the engine from overheating during its
flows through the radiator, radiator hoses, heater core, heater
hoses and water pump which circulates the coolant throughout the system. As the
cooling system ages it can leak which will allow the coolant level to drop and
engine to overheat
What Goes Wrong?
The coolant system consists of rubber hoses, gaskets and seals which are
subject to engine heat and vibration which in time can cause these items to fail
and start leaking antifreeze. With some minor troubleshooting you can find where
the leak is coming from to see if you can fix it yourself or have a repair
garage do it for you.
How Much Does it Cost?
Costs for a coolant leak repair can range depending on the problem which could be as
simple as a radiator hose or about $45.00 (US) and as difficult as a head gasket
or about $1400.00 (US). The best thing to do when you spot a leak is to try and
find it and see what it will take to fix it.
Let's Get Started!
There will be two kinds of coolant leaks, both will
cause the engine to run hot and boil over
. The first kind of leak will be
obvious and can be easily detected while the second kind of leak will be noticed
as the coolant level low warning light will come on while the coolant level slowly drops
down over time as you continually add coolant. Before checking for leaks wait until the engine is cool
and then open the hood for inspection. Many times just by looking around the
engine bay you can detect a leak using a flashlight and looking for green,
orange or blue coolant. We will start with the easier problems and then
continue to the more difficult to find repairs.
1. Loose or Broken Hose Clamp
Spring loaded or O ring hose clamps are use to connect various cooling system
accessories such as a radiator or water pump. These connections can leak due to a
failing O ring or a broken or misaligned hose clamp. In the image below we show
a worm style clamp which is loose allowing coolant to leak from the system.
Sometimes a radiator hose will not seal well due is corrosion under the hose
or the hose clamp being not positioned correctly. Release the cooling system
pressure by slowly removing the radiator cap and reposition or
2. Radiator Hose Leak
A radiator hose retains pressure when the engine is in operation. Because
these hoses are made of rubber they can get fatigued and burst allowing coolant
to leak from the system. These leaks are usually very obvious and sudden and
will require the
coolant hose to be replaced
to prevent engine damage.
3. Heater Hose Leak
Heater hoses are used to transfer hot coolant from the engine to the heater
core where the heated coolant is used to provide comfort to the passengers of
the car in cold weather. If the heater hoses fail coolant will leak inside the engine
compartment on the passenger's side and create steam as the hot coolant is
vaporized on the exhaust manifold indicating the
heater hoses need to be
4. Radiator Leak
is designed to allow coolant to flow
through its internal cooling tubes
which will help the engine run at a normal operating range. When a radiator
ages it can cause one of its plastic tanks to crack which will allow antifreeze to leak
out. When this problem occurs it will sometimes leave signs of dried coolant which can be
detected by an inspection. While
replacing the radiator
in the image below we also
flushed the cooling system
to help prevent the
from becoming acidic which will cause additional leaks.
5. Water Pump Leak
A water pump
mounted to the engine block or timing chain cover and is designed to circulate
coolant throughout the radiator, engine block and cylinder heads. A main
shaft seal is used to prevent coolant from leaking from the pump housing. When
water pump seal fails
it allows a leak from the pump's weep hole which is
seen in the image below. To stop the leak you must
additional parts to replace the water pump
such as a serpentine belt or
6. Coolant Reservoir Leak
A common coolant leak can be traced to the radiator coolant reservoir which will
continuously cause the cooling system to lose coolant. Because the coolant
reservoir is made of plastic it can crack allowing the leak as the radiator
pushes expanding coolant into it. Using a flashlight inspect the tank and if a
leak is found
replace the coolant reservoir tank
with a new part to fix the problem.
7. Cooling System Pressure Test
Sometimes when a coolant leak is not obvious you must create pressure inside
the system to force the leak to appear. This is done
using a cooling system
which you can get from Amazon for about $55.00 (US). If the
cooling system is low and the leak is in the upper portion of the system it can
be difficult to find because just air will leak out. Refill the system with
water and use the tester to apply pressure multiple times
until the leak can be found.
8. Head Gasket Leak
The head gasket is designed to seal the cylinder head to the engine block.
This gasket is made with steal rings embedded into its material to help project
the gasket from the extreme pressures the engine produces in the combustion
process. Over time heat and corrosion with cause the gasket to leak internally
in most cases either pushing exhaust into the cooling system or allowing coolant
to leak inside of the engine. There are
that can be used to determine if the head gasket has failed
in which case
the gasket should be replaced.
9. Intake Manifold Gasket Leak
An intake manifold gasket is used to seal the intake manifold to the
. This gasket helps seal the engine's vacuum and coolant passages which
feed either cylinder head on some V8 and V6 engines on one cylinder head on
straight 6 and 4 cylinders. When this gasket goes bad it can allow coolant to
leak either outside or inside the engine. It usually takes between three and
four hours to
replace the intake manifold gasket
to avoid any engine damage.
10. Freeze Plug Leak
A set of freeze plugs are designed into a car’s engine block as a safety
measure incase the engine ever freezes. Most engines will have 6 to 8 of these
plugs in various places which will push out allowing the expanding frozen
coolant to exit the block without cracking it. Freeze plugs are made of a
relatively thin piece of metal which can rot out and allow coolant to leak from
the system. Many times the
system will need to have pressure in it
to observe this kind of leak. When
replacing a freeze plug it recommended replacing all of them to avoid future
11. Heater Core Leaks
The last part of the cooling system is the heater core. This core is
constructed much like a small radiator and in fact looks like a mini version of
the radiator located inside of the HVAC system located in the car on the
passengers side. A coolant leak will appear on the passenger's side floorboard
indicating the heater core
has failed and needs replacement
Got Any Questions?
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, please visit our forum. If you need
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Article first published 2017-01-27