Cooling Systems by elv8X6D1


									Cooling Systems

•   What is an air cooling system, what does
    it do and its components
•   Some manufacturers recommend
    changing engine coolant every two
    years. Explain why this service is
    recommended and what is involved in
    changing the coolant in a liquid cooling
•   Explain what causes the pressure in a
    liquid cooling system and explain why
    liquid cooling systems are pressurized.
•   A liquid cooling system is continually low
    on coolant. Where can this coolant be
    going? Example – external leaks –
    covers all leaks from the cooling system
    that would eventually end up on the
    ground. Where else could it be going?
In Order To Properly Maintain
   And Identify Preventable
Problems To Cooling Systems
 Understanding the Operation
  And Principles Of Cooling
    Systems is Required.
Cooling systems are designed to(3)
• Remove excessive heat produced by the
  engine during combustion and by friction.
• Get the engine up to operating
  temperature as quickly as possible.
• Maintain the engine at its’ optimum
  operating temperature.
• Engines only turn about 33% of the heat
  produced during the combustion process
  into usable energy.
  The Rest has to be removed
• How is this done?(2)
• Cooling systems are only capable of
  removing about 30% of the heat produced
  by the combustion process.
• The exhaust and heat radiating from hot
  components looks after the rest.
  Types of Cooling Systems(2)
• Air Cooling
• Liquid Cooling 
Air Cooling Systems – Pros and
                 Air Cooled engines are
                 light and use a very
                 simple cooling system.
                 Have few if any moving
                 Require little or no
                 Cannot cool as efficiently
                 as liquid cooling systems.
Liquid Cooling Systems
       Use antifreeze (a 50/50 mix of water
       and ethylene glycol).
       This antifreeze circulates through the
       engine absorbing and carrying away
       some excess heat with it.
       These systems are heavy and have
       many parts which require
       They cool an engine far more
       efficiently than an air cooling system.
       Get the engine up to operating
       temperature faster than air cooling.
Air cooling system components
         Air fins – these air fins are placed around
         the cylinder and cylinder head.
         Passing air carries the excessive heat
         away as it passes through the fins.
         Engines not moving through the air at a
         sufficient speed use a fan to blow the air
         through the fins.
         Shrouds – (metal or plastic panels) can
         guide the air past the cooling fins.
         The only maintenance required is
         cleaning of the air fins and fan (if
         equipped), possibly a belt (driving the
         fan) may need adjustment or replaced.
•   It is difficult to control the warm-up time
    with an air cooled engine. (outside air
    temperature plays a major roll)
•   It is difficult to cool the engine evenly.
    (getting the air to flow evenly around the
•   Because of this air cooled engines have
    hot spots.
•   Very difficult to heat the passenger
    compartment of the vehicle.
•   Little or no warning of the engine
• Light weight (almost no extra weight added to
  the engine)
• Few or no moving parts. (nothing to wear)
• Do not rob the engine of power.
• Require virtually no maintenance.
• Cost is far less than a liquid cooling system.
• Paint the air fins on an air cooled engine! (even if
  they are painted from the factory)
• Operate an air cooled engine with the fins plugged
  with anything. (mud, road tar)
• Allow an air cooled engine to operate without air
  flowing through the air fins. (use a household electric
  fan if necessary)
• Drive a hot engine into a deep water hole too
  quickly. (ATV – could crack the engine)
• Run an engine, designed with air shrouds, without
• Keep the air fins clean and free of debris.
  (grass, leaves, sawdust etc.) these can
  cause overheating or even a fire.
• Keep fans and or belts clean and adjusted
• There your maintenance is done.
              Little Quiz
1. List two types of cooling systems.
2. Cooling systems remove about 33% of
   the heat produced by the engine. Where
   does the other 67% go or do?
3. List 5 benefits of air cooling systems.
4. What are a few shortcomings of an air
   cooled engine?
5. What maintenance or precautions are
   necessary for air cooling systems?
      Liquid Cooling Systems
• Many components means much
• Just keeping the coolant in the vehicle can
  be a problem.
• The density of the coolant is important.
  (especially on turbo charged vehicles)
• Anti freeze is poisonous and will pollute
  Parts Requiring Maintenance
• Belts – the water pump is belt driven and the belt
  needs to be maintained and or adjusted.
• Hoses – deteriorate in time and have to be
  checked and possibly replaced.
• Radiator – fins must be checked and possibly
  cleaned from time to time.
• Thermostat – must be replaced according to the
  maintenance schedule or when defective.
• Radiator cap – both valves and seals must
  operate properly (pressure and vacuum).
• Coolant – must be changed because the
  additives get used up.
                  Anti freeze
• Flows through the engine absorbing heat as it
• Is used to heat the passenger compartment.
• Has additives to protect all the aluminum and metal
• Contains a lubricant for the water pump, rad cap
  and thermostat.
• Service life is usually two years.
• Is poisonous to: pets, children and even fools.
• Is colorful and sweet tasting (to make things worse)
• Cooling system leaks can be difficult to find.
• External leaks are the easiest. Coolant leaking on the
  ground (problem should be obvious). Check hoses, water
  pump, radiator and engine gaskets.
• Internal leaks – leaks inside the engine can cause serious
  engine damage. Coolant in the oil or getting into the
  combustion chamber and being burnt by the engine.
• Coolant entering the engine oil will cause a white milky
  looking oil.
• Coolant being burned by the engine will turn sparkplugs
  (country snow white). Possibly cause the engine to miss
  when first started and run properly after a few seconds of
  operation. Cause a very sweet smell coming from the
• Leaks inside the vehicle. These could be a
  heater core or the plumbing inside the vehicle.
  The first sign is the windshield steaming up
  when the heater is on defrost setting.

 •Leaks into the automatic
 transmission cooler. This can
 be either transmission fluid in
 the cooling system or worse
 yet coolant into the automatic
 transmission or both.
                   Radiator Caps

Have two seals. One to hold pressure in the cooling system and
one to prevent spilling fluid onto the ground (make sure the
expanding fluid goes to the overflow bottle.
              Two Valves
• A pressure relief valve is used to prevent
  the cooling system from becoming over
  pressured and result in leaks or broken
• A vacuum valve is also part of the radiator
  cap and this valve allows the overflowed
  coolant back into the engine as the coolant
  cools. The coolant contracts as it cools
  and creates a vacuum in the cooling
      Just a good time to ask
• What causes the pressure in a cooling
• Its not the water pump.
• Its not the radiator cap.
• Its not the thermostat.
• It’s the heating of the coolant by the
  combustion heat. That’s right as we heat a
  fluid it expands and thereby creating the
  pressure in the cooling system.
• Keeping pressure in the cooling system allows
  higher engine operating temperatures without
  boiling the coolant. (engines run more efficiently
  at higher temperatures)
• Up to 110-115 degrees Celsius is acceptable
  and that is 10-15 degrees above the boiling
  point of water.
• If the pressure is released quickly the coolant
  will immediately boil and blow off with great
• This is the reason for not opening a hot cooling
Never Open HOT
 Cooling systems get hotter when
      we shut off the engine.
• When the engine is shut off the water
  pump stops circulating the coolant.
• The coolant just sits there absorbing more
  and more heat.
• Shut off a hot engine and about 10-15
  minutes later just turn the key on (do not
  start the engine) and observe the
  temperature gauge.
• This is known as a Heat Soak Condition.
           Thermostats Job
• Thermostats are designed to stop or allow
  coolant flow to the radiator.
• When the engine is cold it stops the flow to
  the radiator allowing the engine to warm-
  up quickly.
• As the engine gets up to a predetermined
  operating temperature the thermostat
  opens allowing some coolant to flow to the
  radiator to be cooled.
• So we could say, the thermostat controls
  engine warm-up and gets the engine up to
  operating temperature as quickly as
  possible (more efficient) and maintains it
  at that temperature.
• A thermostat that is stuck in the open
  position will not allow the engine to warm-
  up quickly (or at all for that matter)
• The first indication is a vehicle that will not
  warm up the passenger compartment and
  could be a little hard on fuel
• Thermostats are moving parts and do
  require replacement about every couple of
  years to be safe.
• The days of a hotter thermostat in the
  winter and a cooler one in the summer are
  gone. (one temperature for all seasons
• You should never operate an engine
  without a thermostat installed. The engine
  will not get up to operating temperature
  and waste gas. Remember engines wear
  more quickly when they are not up to
  operating temperature.

Make sure the thermostat is inserted into the recess or you
could break the thermostat housing when you tighten it up.
    What do you think caused this

This thermostat housing was attacked by the coolant either
not being aluminum compatible or too old and the anti-
corrosion additives have been used up and couldn’t
protect the housing.
• When the engine is cold coolant flows
  through the engine water jackets, around
  the cylinders and cylinder head and to the
• This helps the engine warm-up quickly
  because no coolant goes to the radiator.
• This means you should be able to hold
  onto the upper rad hose when the engine
  is cold and running and it should not get
• If it does get warm, the thermostat is
  partially open and needs to be replaced.
• Once the engine gets up to operating
  temperature the thermostat opens and
  then coolant flows everywhere it did with
  the cold engine plus out through the upper
  rad hose to the radiator, down through the
  radiator and back to the water pump
  through the lower rad hose.
• Now you can’t hold onto the upper rad
  hose. It will be too hot.
• Coolant flow is important because when
  you flush the cooling system you want to
  make the liquid flow in the opposite
  direction. (Reverse flushing)
• All liquid cooled engines require a fan to
  move the air through the radiator when the
  vehicle is not moving at a sufficient speed
  through the air.
• Many different designs are used.
Electric Fan
      Electric fans put very little
      drag on an engine and can
      turn on and off automatically
      when needed.
Solid Fan
    Solid fans are driven by a
    belt connected to the
    crankshaft and take a lot of
    engine power to turn at all
    times (needed or not).
    This is the least economical
    of all fans but is a good
    choice for plows or trucks
    working in the woods.
Flex Fan

   These fans are also belt driven
   from the crankshaft and run at
   all times.
   The big difference is that the
   blades straighten out at high
   speeds (when a fan is not
   needed) reducing the drag on
   the engine.
Clutch Fan
       These fans are driven by a
       clutch which is driven from
       a belt connected to the
       When heat (coming
       through the radiator) heats
       up the clutch, it locks up
       and the fan spins as a solid
       fan would.
       Cool air on the clutch
       unlocks the clutch and the
       fan “free-wheels” reducing
       the drag on the engine
• Clutch fans (for some reason) are popular on
  trucks and four wheel drive vehicles.
• (thought) - This doesn’t make sense if the
  vehicle is to be used to plow snow or be
  driven through the woods at slow speed.
• Slow speed operation can prevent the hot air
  passing through the radiator therefore the
  clutch will not lock up the fan. (not enough air
  passing through the radiator at slow speeds)
• When this happens the engine can be
  overheating and the fan will not suck the
  needed air through the radiator to cool things
• All you 4X4 nuts keep in mind, a fan turns
  into a propeller when submerged under
• This can cause the fan to flex into the
  radiator. (you’re in trouble now)
• Electric fans are popular for these
  applications as they can be turned off
  under these conditions and don’t have
  enough power to hurt anything even if they
  are running.

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