Chapter 13 Diesel Engine Cooling Systems
Pumps can be
Belt - or gear driven
Coolant Extender
An Additive package that is only used with ELC, which is added at the midpoint of the coolants life.
15-17 PSI
An adapter may be required to seal the tool to the neck of the surge tank or radiator. pressurize the system to.
Propylene-Glycol
An anti-freeze base that is non-toxic and environmentally friendly.
230F
An exception is emergency and military engines that are designed to withstand as much as
Cooling systems must provide
For expansion of coolant.
Nitrite, When Added to Coolant
Forms a Thin, Protective film on the coolant side of the engine cylinder walls and other surfaces to reduce cavitation erosion.
Antifreeze AKA Coolant
Freeze and boil protection are both provided to the engine by the use of.
Cylinder heads, blocks, water pumps, and radiators
Frozen Coolant can easily break and Crack
-36F
Glycerin can only provide a freeze protection to
Diluted to a 30/70 Water-to glycerin concentration
Glycerin can only provide a freeze protection to -36F. At that concentration glycerin-based coolant is not able to remove as much heat as a mixture with higher amount of water.
17%
Greenhouse Gas (GHG) Emission standards for heavy-duty diesels require an increase in thermal efficiency for diesel engines by 2025.
A Blocked Thermostat
Has a Hollow center.
20-25%
How much is emitted by the exhaust system.
30-35%
How much of The remaining energy is absorbed by the cooling system.
2 Volts
If the Voltage exceeds ________ the cooling system should be drained and flushed, And new coolant that contains the recommended level of conditioners should be added.
Cross-Flow Radiators Are preferred
In Vehicles with low-profile aerodynamic hoods because they can be made wider with a lower height profile.
Every 1 PSI Increase
In cooling system pressure increases the boiling point by approximately 3 F, This means 10psi of pressure on the cooling system raises its boiling point to 242 F
400F
Intake air compressed by the turbocharger easily heats to over?
All Diesel cooling Systems
Need to use special conditioners to prevent or minimize cavitation erosion.
Currently No Vehicle OEM Uses a factory of NOAT Anti-freeze.
Nitrated Organic Acid Technology (NOAT)
Over 50%
Of Catastrophic engine failures can be attributed to cooling system failures
Heat Generated By Combustion is
Rejected and transferred to engine parts and lubrication oil.
Hot engine Surfaces where coolant turbulence is low.
Scale And Deposits formation Commonly occur on.
Short Out
Sensors and other electrical devices that are exposed to engine coolant have the potential to
Any Fluid Leakage And Damaged Hubs
Should be taken out of service.
Only Low-Silicate Anti-freeze
Should be used in diesel engines because the addition of nitrite to diesel coolant will cause silicate dropout, Which can lead to plugged Radiators, Water pump seal leaks, and overheated engines.
Type III Fully formulated Propylene Glycol extended-life OAT
Suggested color Blue
A Simplified Way of Stating Thermal Efficiency
Would be to compare the mechanical energy available at the flywheel to the cost of fuel.
Both OAT And IAT Were primarily developed
To treat or condition the cooling system to reduce the effects of Cavitation erosion.
40 percent
0.06 deposits will reduce heat by how much.
Diesel Coolant Additive (DCA)
An Additive used to treat cooling systems to reduce the effects of cavitation erosion.
Organic Acid Technology (OAT)
A category of ELC containing carbon-based corrosion inhibitors.
300,000 Miles or 6000 Hours
A coolant Extender must be added only once at (482,800 km) which is about halfway through the anti-freezes service, if a longer service is expected.
0-14 With 7 Being Neutral
A materials pH is measured on a scale of
Choking And full blocking thermostats operate by using
A special wax pellet combined with a powered metal tightly squeezed into a copper cup that is equipped with a piston inside a rubber boot. Heat causes the wax pellet to expand, which pushes the piston upward, opening the valve.
Constant Torque spring clamps
Allow hose to ends to thermally expand and contract, which minimize coolant loss from hose clamps.
A Vacuum Valve Incorporated into the cap
Allows Air to coolant to Re-enter the cooling system when the pressure drop after the engine cools.
The 1" Tube Size
Also increased tube-to-fin contact and cooling capacity by roughly 25%
A Two-Row Aluminum Radiator core
Also referred to as a double core radiator with a 1" Circumference tubes is equivalent to a five-row copper brass radiator with 1/2" circumference tubes.
Radiators
Are Heat exchanging devices that release heat into the atmosphere from the engine to the air. Coolant can flow in a radiator in two ways.
All Water Pumps
Are centrifugal turbine pumps, which means they become more efficient the faster they turn.
Engine Fans
Are designed to increase the airflow across the radiator, which improves the efficiency of heat removal from coolant.
Core Plugs
Are not designed to relieve pressure from frozen coolant to prevent engine damage.
Faulty Vacuum Valves
Are often identified when the upper radiator hoses collapse after the engine cools or when coolant is lost.
Constant Torque Clamps
Are the best clamps to use to minimize coolant loss, because they change dimensionally with the expansion and contraction of hoses and connections.
180F
At a predetermined point (82C) The Thermostat will begin to open, and it will continue to open further if the coolant temperature continues to increase.
Coolant Flow is Regulated
By Movement of the outer sleeve to block or open passage ways to either the radiator or bypass hose.
Nitrite Protects
Cast iron, Steel, Aluminum, And Solder
A pressure tester, Refractometer
Common tools needed to service cooling.
Over 65%
Concentration and the coolant will not remove heat effectively and will in fact lose its freeze protection.
coolant with less than 40%
Concentration of anti-freeze may not contain enough corrosion inhibitors.
8.5 And 10.5
Coolant And pH should be maintained between.
When the Engine Cools
Coolant Is drawn back into the radiator through negative pressure induced by the contraction of cool coolant in the closed cooling system.
In Cross-Flow Radiators
Coolant will flow from a top-connected hose, through a side-mounted tank, into cooling tubes, and across the radiator to another side -mounted tank.
Glycerin-Based
Cummins makes currently produces a anti-freeze, complete that meets the recently developed ASTM international standard for the latest antifreeze technology.
5% to 25%
Depenfing on the type of formulation, acceptable contamination can range from. Though most OEMs do not recommend contamination of 5%
A Gear Driven Pump
Does not rely on a belt, which minimizes service requirements and is more reliable than a belt for long distances.
Most Engines Use Air To Air After cooling (ATAAC)
Engine coolant is often used to help reduce charge air temperatures, Which lower Air Inlet Temperatures.
25HP
Engine fans consume a lot of power easily 19kW on heavy duty engines, the fan is often activated with the engine brake to increase the engine resistance to driveline rotation.
Phosphate Protects
Iron And pH control (keeps coolant alkaline between (8.5-10.5)
The use of a Hydrometer or Refractometer
Is Necessary when testing the freeze protection of the coolant in the cooling system.
The Primary function of the cooling system
Is Transferring heat absorbed from the engine to the Atmosphere.
Between 3% And 5% Of DCA or SCA
Is added after the initial mixing of anti-freeze and water to bring the additive package for diesel engines to the correct protection level.
White Exhaust Smokes that smells sweet
Is an indication of an EGR Cooler leak. the problem can worsen with hard acceleration.
Distilled Water
Is best for cooling systems because it has no mineral content to scale or deposit, on a cooling system.
Silicate Dropout
Is characterized by the appearance of green "Goo" or gel that plugs radiator and heater core tubes, leading to over heating of the engine and even catasphropic failure
Type I Anti-freeze for diesel Engines
Is different from type I Anti-freeze for gasoline engines and the two should never be exchanged. Gasoline Engines Use Type I Anti-Freeze that contain higher Silicate levels.
Green Dye
Is later added for identification. one of the most significant reasons ethylene glycol is dyed is to clearly distinguish it from other coolants, because it is extremely poisonous.
Type II Anti-Freeze
Is made from ethylene glycol.
Type III Anti-Freeze
Is made from propylene Glycol.
A 50/50 Mixture
Is optimal for removing heat and providing corrosion protection.
Sodium Silicate
Is primarily used to protect aluminum and is found in much higher concentration when used in gasoline engines with alumininum cylinder heads.
The Primary disadvantage Of Glycerin
Is that its freeze protection temperature is high in comparison to ethylene Glycol.
Water
Is the most efficient fluid to transfer heat.
Water mixed with Antifreeze And other ingredients
Is the primary coolant medium to absorb engine heat.
A Refractometer
Is used to test coolant mixture and freeze protection by testing the fluids ability to bend light. This tester can be used with any type of anti-freeze.
If it coolant Increases above 11
It will become aggressive to aluminum and Solder in a cooling system.
If coolant drops below 8.5
It will become aggressive to ferrous metals (cast iron and Steel) Aluminum, copper, and brass.
More than 50% Thermal Efficiency
Larger, Slow- Speed Industrial diesel engines used on Ships and for electric power generation can operate at more than.
Intake Manifold to circulate coolant, Which lowers air inlet temperatures.
Liquid heat exchangers, charge air coolers, or after coolers.
Vent Lines
Located at the highest points on the engine and radiator bleed any steam and air out of the engine and into the surge tank.
leaking Head Gaskets, Or Air Compressors Can Consume Coolant
Loss of engine coolant without any visible external leaks may be caused by a variety of internal leaks or over-pressurizing of the cooling system forcing coolant out the over-flow tank.
Between 180F And 200F
Machined Parts operating with close tolerances require consistent operating temperatures.
40%
Manufacturers studies report as much as _____ Of all engine maintenance or breakdown is related directly or indirectly to cooling Systems.
Upper Radiator Hoses
More commonly fail first.
Cavitation Occurs
More easily if cooling system pressures are abnormally low.
In The 1980s
Most Manufacturers began to use aluminum tube radiators.
The largest holes are located
On the opposite side of the gasket from the thermostat. This requires coolant to flow across the head to properly cool the head before reaching the thermostat housing.
pH Levels
One Major factor affecting the corrosion rate of the metals in an engine is the coolants?
Electrical Current
Passing through the coolant will quickly erode brass and aluminum oil coolers, injector tubes, and other metals in the cooling system.
Type I Additive Deplete
Quickly and require monitoring. With time, Many of these Additives other components, Such as phosphorus, drop out with the silicate, coating cooling system component's with a layer of slime and deposits.
An Electrically controlled Variable speed engine fan
Reduces parasitic power loss and provides optimal ECM control of fan speed.
Thermostats
Regulate the temperature of the engine coolant by modulating or controlling the volume of coolant circulated to the radiator.
The Sharp Increase in Combustion Pressure Also creates
Temporary pressure voids on the coolant side of the blocks cylinder walls, which produce cavitation erosion.
A Coolant Extender
That contains Nitrite for protection against cavitation erosion has an additive similar to SCA/DCA.
higher Than 60% or lower than 40%
The Anti-freeze in the water mixture should never be.
Five years Or 150,000 miles
The Normal NOAT service life, And uses an extender package halfway through the service life.
85%
The Radiator cap is also important to water pump efficiency. When the cooling system is pressurized, the pumps operates much better than the How Much Efficiency without pressure cap.
Mixing IAT with OAT, HOAT, And NOAT Anti-freezes
Will not damage the engines cooling system. However, mixing anti-freezes nullifies the extended-life attributes of these formulations.
Down-Flow Radiators
The coolant will enter through a hose connected to the top of the tank that is carrying hot coolant from the water pump outlet. The coolant will then flow from the top tank, through cooling tubes, and into the bottom tank.
600,000 Miles on Road, Or 12,000 hours off-road.
The corrosion inhibitors in these types of ELC Anti-freeze are designed to last.
10-15F
The temperature at which the fan will engage is how much above the coolant operating temperature.
Heat Rejection
The transfer of heat into the cooling system from the combustion chamber.
Organic Acid technology (OAT) And Inorganic Additive Technology (IAT)
There are two categories of conditioner.
Type II And Type III
These Anti-freezes generally do not require An initial charge of DCA or SCA because it is incorporated into the solution during Manufacture.
Galvanic Effect
These principle of inducing current flow by using dissimilar metals and electrolyte is called the.
Type IV Anti-freeze
This Red colored anti-freeze is commonly used in todays diesel and gasoline engines, This Type of anti-freeze use non-carboxylate acids, such as benzoate, from benzoic acid, to form the additive package.
Electrical Conduction
Through coolant quickly eliminates nitrite additives in coolant, leading to further engine damage
Optical Tachometer
To evaluate these silicone fluid thermostatic fan clutches, the amount of slippage is measured. This is best done with a
Ground Straps
To minimize Electrical Current, engine blocks use a number of what, to not only lower resistance for engine-mounted electrical devices but also to minimize electrical conduction through engine coolant.
Antifreeze contains Corrosion inhibitors
To protect cooling systems materials such s cast iron, aluminum, copper, brass, solder and many non- metallics like nylon and silicon.
A Fan Drive mechanism is used to decouple the fan from the engine when airflow is not required.
To reduce the parasitic loss of power from the engine, which is often more than 25 horsepower (HP) on some heavy duty Fans.
A Refractometer can also be used
To test the proportions of anti-freeze and water in the coolant mix ( Or the level of freeze protection) by measuring a liquids specific gravity.
One side of the head gasket
Typically has more or larger holes than the other.
100%
Until Model year 2002, when cooled EGR was introduced, Most diesels had how much of exhaust heat passed into the atmosphere.
A More Traditional fan engagement Mechanism Is an ON/OFF fan hub
Which Uses air pressure to either engage or release a spring-loaded friction clutch.
The Coolant Is an electrolyte
Which means it can conduct current.
Vapor Implosion In an engine protected by Nitrite
Will Damage only the nitrite layer, which can be replenished from the nitrite dissolved in the coolant.
Coolant in the cylinder of a diesel
Will lock the engine because cylinders have a very little clearance volume.
sodium silicate and nitrite
both these additives together will cause a condition known as silicate dropout.
A weekend hose may
collapse and restrict coolant flow. The bottom radiator hose has an internal spring that prevents the hose collapsing when the engine is suddenly accelerated and the water pump draws more coolant.
Type I Anti-freeze
containing this corrosion inhibitor package should be drained and replaced every two years.
Hose clamps
help the hose seal at its connections.
If Coolant is brown in color,
it often indicates the presence of rust in the coolant. some corrosion inhibitors used to prevent are easily damaged by over heating coolant. coolant that has overheated should not be reused during service.
A cooling System Maintenance
must include the measurement of the level of nitrite to evaluate the level of this important additive.
90-120 Seconds
typically a timer will be connected to the circuit to keep the fan engaged for...to prevent excessive cycling between on and off which will wear out the friction clutch faster.
Type 1 conventional Anti-freeze
uses older additive technology and contains corrosion inhibitors, such as boron, phosphate, sodium silicate.
Hybrid Organic Acid Technology (HOAT)
A combination of IAT And OAT with nitrites added, making it suitable for both use in both light- And Heavy duty systems.
Aeration
A condition in which excessive amounts of air or steam bubbles are dissolved in coolant, diminishing the coolants effectiveness.
0.2 Volts or Less
A cooling System with a level of Additives that is adequate to protect metals from corrosion will test at
Inorganic Additive Technology (IAT)
A diesel engine cooling system conditioner containing non-carbon-based corrosion inhibitors Such as phosphate, borates, and silicate.
Electrolyte
A substance that can Conduct current.
Heat Exchanger
A system that transfers heat from the coolant to the Atmosphere.
Diesel Cooling Systems
Also need specialized attention because of unique heat loads and combustion characteristics that affect coolant maintenance practices.
Pressurizing The Cooling Systems
Also prevents water from boiling away from the cooling system.
Supplemental Coolant Additive (SCA)
An Additive used to treat cooling systems to reduce the effects of cavitation erosion and optimize cooling system performance.
Nitrated-Organic Acid Technology (NOAT)
An ELC Using OAT with Nitrates added.
Core plugs AKA Frost Plugs
Are pushed out by frozen coolant, which causes a major loss in coolant.
Liquid Interstage Coolers
Are used on Series turbo charged engines to reduce, air temperatures between the LOW- And HIGH- pressure turbochargers.
Surge Tanks, Overflow Reservoirs And large Radiator Tanks
Are used to buffer coolant expansion.
Thermal Efficiency Is measured
As a percentage of the potential energy content in fuel compared with the engines ability to convert the potential energy into mechanical energy.
It Expands
As engine coolant Warms,
250F
At temperatures above ________, Oil can quickly oxidize and even burn.
The Coolant System Is pressurized by
Both Coolant expansion and Trapped Air, Including Steam trapped in the radiator during heating.
Nitrite
Both new and old formulations of anti-freeze for diesel engines use a critical additive to minimize cavitation erosion.
Scale
Can come from Calcium and magnesium in the water used for cooling.
Dissimilar Metals In Contact with Engine Coolant
Cause electrochemical reactions
Even When Coolant Is Relatively Cold
Coolant next to hot interior engine surfaces becomes hotter than surrounding coolant and vaporizes.
Will Produce More Voltage
Coolant that has become depleted of additives or highly acidic or alkaline.
First- Is to maintain pressure greater than atmospheric pressure at the water pump inlet. Second - The Second Important reason for pressurizing the cooling system is that it increases the boiling point of water.
Cooling Systems Are pressurized for two important reasons.
Approximately 45% Thermal Efficiency
Currently, The best heavy-duty on highway diesel engines operate at. Which means that 45% of the fuel energy released during combustion is converted into mechanical energy and available to the flywheel.
12 F Beyond Normal operating Range
Cylinder wall wear begins to dramatically increase.
Coolant Systems Must provide for
Deaeration Of coolant to prevent pumps and coolant passage ways in the cylinder head from becoming Air bound, Or blocked by an accumulation of steam.
15-40%
Diesel-Powered Vehicles cooling system needs to Dissipate _________ More heat absorbed from exhaust gas.
Increasing Cooling System Pressure will prevent
Engine damage and loss of coolant by increasing the temperature at which coolant will boil.
Larger Water pumps, Cooling Fans, And radiator Cross-sectional areas combined with increased under hood airflow are needed to remove the additional heat from the cooling system.
Engine modifications to deal with the increased heat loads include.
Cavitation
Erosion in cylinder blocks walls, heads, and liner sleeves as a result of the collapse of tiny water vapor bubbles formed when coolant vaporizes on hot cylinder wall surfaces.
Resulting In Cracking of heads and Engine Blocks.
Even Momentary loss of direct coolant contact with coolant would cause severe thermal stress on these components.
The Cooling System Removes
Excess heat from the engine and releases it to the Atmosphere through the radiator.
1200F
Exhaust Gases can reach?
400F
Exhaust Temperatures (1200F) are reduced to how much or less before being mixed with the intake air. Originating from the outlet of the Charge Air Cooler.
Todays Engines More Than Half the heat produced from combustion
Is Wasted through heat radiated from engine surfaces and dissipated from the engine through the cooling system and exhaust gases.
An Over-Flow Reservoir
Is needed to Contain the coolant pushed out of the radiator and engine.
Boiling Coolant
Is not able to effectively absorb heat, because heat it is not in a liquid state.
Compression-Ignition Combustion
Is one of the most thermally efficient processes for converting fuel energy into mechanical energy, It still requires a substantial amount of heat being released to the cooling system.
5%
Is radiated to the Atmosphere through hot engine parts.
Heat Removed from intake air
Is simply Transferred to the atmosphere through the radiator.
Chemical Treatment of the cooling systems
Is the preferred method for minimizing cavitation erosion.
Water
Is the primary ingredient of engine coolant.
If Excess heat is not removed from the oil.
It can lose its viscosity and thin too much to support bearing loads and properly lubricate parts.
When coolant is Frozen
It will not flow, which will cause the cylinder components to rapidly over heat, Thermally stressing the cylinder block and head to the point of cracking.
60%
Of Water pump failures are caused by preventable seal leakage.
Up to 30%
Of intake air mass in most current diesels will include exhaust gases, which can Reach 1200F
Friction And The Energy Required To Move Gases in And Out
Of the Engine account for the remaining losses in thermal efficiency.
Setting The Multi-Meter to a low-voltage DC Scale
One test lead is placed in the coolant . The other test lead can be placed anywhere on the engine where metal is exposed.
60,000 PSI
Pressure exerted by the force of bubble collapse is reported to be as high as.
The Cooling system can behave like a
Primary battery in which dissimilar metals in the presence of an electrolyte will produce a flow of electric current.
Extended-Life Coolant (ELC)
Several Types of long-life coolant formulations containing an anti-corrosion additive package that does not deplete; Also known as long-life coolant (LLC).
Some metals in contact with coolant will be
Severely and quickly corroded through these chemical reactions.
As Coolant Warms
Some Vaporization occurs, forming bubbles and vapor pockets.
Phosphate, Silicate, And Nitrate
Some scale is produced by additives in the antifreeze such as
Oil Cooler Nozzles
Spray the underside of all engine pistons crowns with oil to remove heat. The heat is absorbed by the oil is removed by the cooling system through the oil cooler.
Series Turbo Charging
Temperatures are even higher than 400 degrees on engines using.
Recapturing Energy
That would normally be lost in the exhaust system to power a turbo charger can increase the thermal efficiency of a diesel engine; This one way that heat energy is removed by diesels.
3900 F
The Flame Temperature of diesel fuel is approximately
25-30% Thermal Efficiency
The Thermal Efficiency of todays diesel engines is almost double that of spark-ignition engines, which operate at up to approximately.
Thermal Efficiency
The ability of an engine to convert the energy content of fuel into mechanical energy.
Ethylene-Glycol
The base chemical from which the majority of Anti-freezes are made.
Cavitation Erosion is Caused by
The collapse of tiny water vapor bubbles formed when coolant rapidly heats next to hot surfaces , or the coolant is subjected to a rapid drop in pressure.
Cooled (EGR)
Which has been used by diesels for the past decade and a half, places even lager heat load on the cooling system.
Higher compression Ratios, Lean Burn Combustion, The absence of a throttle Valve.
Why is the Thermal Efficiency of Diesel Engines higher than that of Petrol Engines?
Higher Operating Temperatures
Will lower the amount of heat rejected, but if temperatures climb even as 12F beyond normal range, cylinder wall wear begins to dramatically increase.
Galvanic Activity In a cooling System is measured.
With a Digital Multi Meter.
Scale And Deposits On Internal Surfaces
Within the engine and cooling system can sharply reduce heat transfer.
0.06
deposit will reduce heat by 40%
Core plugs or Frost plugs are used to seal
passage ways in cylinder blocks and head casting designed to flush sand from casting after manufacturing.
