Chapter 14
Lubricating and Cooling Systems
© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied,
duplicated, or posted to a publicly accessible website, in whole or in part.
Lubrication System
• Holds an adequate
supply of oil
• Lubricates parts and
reduces wear
• Delivers oil to
necessary areas of
engine
© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied,
duplicated, or posted to a publicly accessible website, in whole or in part.
Lubrication System (Cont.)
• Cools and cleans components
• Helps seal the engine
• Removes contaminates
© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied,
duplicated, or posted to a publicly accessible website, in whole or in part.
Engine Oil
•
•
•
•
•
Formulated to lubricate and cool parts
Moving engine parts fed constant supply
Stored in oil pan or sump
Moves from sump to oil filter
Moves throughout engine via oil gallery
© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied,
duplicated, or posted to a publicly accessible website, in whole or in part.
Oil Pump
• Pickup screen keeps large particles out of
the pump
• Oil pressure relief valve prevents excessive
oil pressure
© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied,
duplicated, or posted to a publicly accessible website, in whole or in part.
Oil Pan or Sump
• Wet sump always
has oil in it –
most engine
applications are
wet sump
systems
• Baffles reduce
sloshing
© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied,
duplicated, or posted to a publicly accessible website, in whole or in part.
Dry Sump
•
•
•
•
•
•
Used to eliminate oil sloshing
The oil pan does not store oil
Oil reservoir is mounted remotely
Can feed oil along multiple paths at once
May have one or two oil pumps
Allows for lower engine placement
© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied,
duplicated, or posted to a publicly accessible website, in whole or in part.
Oil Filter
• All oil leaving the
pump goes to the
filter
• Threads onto a main
oil gallery tube
• Can be single
disposable container
or a cartridge
© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied,
duplicated, or posted to a publicly accessible website, in whole or in part.
Cartridge Oil Filter
© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied,
duplicated, or posted to a publicly accessible website, in whole or in part.
Oil Filter (Cont.)
• Some filters use an
anti-drainback valve
• If the filter becomes
plugged, a valve opens
to allow oil to bypass
the filter
© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied,
duplicated, or posted to a publicly accessible website, in whole or in part.
Flow Through the Oil Filter
© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied,
duplicated, or posted to a publicly accessible website, in whole or in part.
Oil Coolers
• Used on many diesel,
high-performance,
and turbocharged
engines
• Now common on
passenger car engines
• Oil flows from pump
to cooler and then to
the engine
© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied,
duplicated, or posted to a publicly accessible website, in whole or in part.
Engine Oil Passages or Galleries
© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied,
duplicated, or posted to a publicly accessible website, in whole or in part.
Dipstick
• Used to measure the oil
level in the oil pan
• Some engines do not
have a dipstick
• Oil level is checked by
an oil sensor
• Oil level is displayed on
the dash
© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied,
duplicated, or posted to a publicly accessible website, in whole or in part.
Oil Pressure Indicator
• All vehicles have either a gauge or light
• Most gauges are electronic
• Warning light circuits are completed if oil
pressure falls below a certain level
• Some vehicles use an electronic oil level
indicator to alert the driver if the level drops
below a predetermined level
© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied,
duplicated, or posted to a publicly accessible website, in whole or in part.
Oil Pressure Indicator (Cont.)
© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied,
duplicated, or posted to a publicly accessible website, in whole or in part.
Knowledge Check
• Describe the flow of oil in the lubrication
system.
© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied,
duplicated, or posted to a publicly accessible website, in whole or in part.
Oil Pump Inspection
•
•
•
•
Mark gears before disassembly
Check gears and housing for wear
Measure gear-to-pump clearance
Inspect the pickup for sludge and debris
© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied,
duplicated, or posted to a publicly accessible website, in whole or in part.
Engine Lubrication
Diagnosis and Service
• Oil level should be checked periodically
• The oil filter is changed with the oil
• Oil pump performance can be checked with
an oil pressure gauge
• Passages and galleries should be cleaned
during an engine rebuild
© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied,
duplicated, or posted to a publicly accessible website, in whole or in part.
Oil Consumption
• External and internal
leaks
• Worn piston rings
allow blowby
• Worn valve seals or
guides
© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied,
duplicated, or posted to a publicly accessible website, in whole or in part.
Oil Consumption (Cont.)
• Blue smoke indicates
internal leak present
• External leaks occur at
gaskets and seals
• Oil usage increases
engine wears
© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied,
duplicated, or posted to a publicly accessible website, in whole or in part.
Common External Oil Leaks
© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied,
duplicated, or posted to a publicly accessible website, in whole or in part.
Sludge
•
•
•
•
•
Results from oxidation of the oil
The oil begins to solidify and form a gel
This gel cannot circulate
Can block normal oil paths
Signs include low oil pressure, increased oil
consumption, increased emissions, and poor
driveability
© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied,
duplicated, or posted to a publicly accessible website, in whole or in part.
© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied,
duplicated, or posted to a publicly accessible website, in whole or in part.
Sludge (Cont.)
• A slight amount under oil cap is normal
• Sludge can be caused by:
– A plugged PCV system
– Extended oil change intervals
– Low viscosity oils
– High operating temperatures
– Very lean mixtures
© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied,
duplicated, or posted to a publicly accessible website, in whole or in part.
Flushing the System
• Refer to the manufacturer’s service
information before performing a flush
• Running a solvent through the engine oil
system and then draining
• May help to remove sludge
© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied,
duplicated, or posted to a publicly accessible website, in whole or in part.
Oil Cooler
• Inspect cooler and lines for leaks
• Flush or replace if there is sludge buildup in
the engine
• Replace the cooler and clean the lines after an
engine rebuild
© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied,
duplicated, or posted to a publicly accessible website, in whole or in part.
Knowledge Check
• What are three possible causes of oil sludge in
an engine?
© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied,
duplicated, or posted to a publicly accessible website, in whole or in part.
Cooling Systems
•
•
•
•
Removes heat generated during combustion
Must allow quick engine warm up
Heat is transferred by the coolant
The coolant transfers the heat to the
surrounding air
© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied,
duplicated, or posted to a publicly accessible website, in whole or in part.
Cooling System Components
•
•
•
•
•
Thermostat
Water pump
Radiator
Radiator pressure cap
Expansion tank
•
•
•
•
•
Hoses
Water outlet
Water jackets
Cooling fans
Temperature indicators
© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied,
duplicated, or posted to a publicly accessible website, in whole or in part.
Cooling System Components
(Cont.)
© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied,
duplicated, or posted to a publicly accessible website, in whole or in part.
Thermostat
• Controls the minimum operating temperature
• Temperature sensitive flow control valve
• Contains a wax pellet that expands, forcing
the thermostat to open
• Usually mounted on the top and front of the
engine
• The heat element is recessed into the block
© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied,
duplicated, or posted to a publicly accessible website, in whole or in part.
© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied,
duplicated, or posted to a publicly accessible website, in whole or in part.
Water Pump
• Usually belt driven but some are driven via the
cam or an electric motor
• The rotating impeller circulates the coolant
• The pump inlet is connected to the lower
radiator hose
• The pump outlet is connected to the engine
block
© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied,
duplicated, or posted to a publicly accessible website, in whole or in part.
Water Pump (Cont.)
© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied,
duplicated, or posted to a publicly accessible website, in whole or in part.
Radiator
• Exchanges heat from the coolant to the
surrounding air
• Constructed of aluminum, brass, plastic
• Radiator efficiency:
– Basic design
– Size of core
– Amount of coolant flow through the core
– Temperature of the cooling air
© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied,
duplicated, or posted to a publicly accessible website, in whole or in part.
© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied,
duplicated, or posted to a publicly accessible website, in whole or in part.
Radiator Pressure Cap
• Allows pressure to rise in cooling system
• 1 PSI of pressure increases boiling point about
3.25 degrees F (1.8 °C)
• Caps normally hold between 14 – 18 PSI
• Vents coolant to reservoir at specified PSI
• Allows coolant back into engine when cool
© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied,
duplicated, or posted to a publicly accessible website, in whole or in part.
Radiator Cap
Pressure operation
Vacuum operation
© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied,
duplicated, or posted to a publicly accessible website, in whole or in part.
Expansion Tank
• Designed to
catch and hold
coolant passing
from radiator
cap as the
coolant expands
© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied,
duplicated, or posted to a publicly accessible website, in whole or in part.
Hoses
• Made of butyl or neoprene rubber
• Cushion engine vibrations and movement
• Most vehicles have at least four hoses while
some have five
– Upper and lower radiator hoses
– Heater hoses
– Bypass hose
© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied,
duplicated, or posted to a publicly accessible website, in whole or in part.
Knowledge Check
• What is the purpose in allowing pressure to
increase in the cooling system?
© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied,
duplicated, or posted to a publicly accessible website, in whole or in part.
Water Outlet
• Connects the engine and upper radiator hose
• Also called a gooseneck, elbow, inlet, outlet,
or thermostat housing
• May cover thermostat
© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied,
duplicated, or posted to a publicly accessible website, in whole or in part.
Water Jackets
• Surround combustion chambers
• Some engines use plastic inserts to direct
coolant flow within the jacket
• Includes core plugs and block drain
© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied,
duplicated, or posted to a publicly accessible website, in whole or in part.
Water Jackets
© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied,
duplicated, or posted to a publicly accessible website, in whole or in part.
Hose Clamps
• Designed to apply consistent clamping
pressure
© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied,
duplicated, or posted to a publicly accessible website, in whole or in part.
Belt Drives
• Used to drive the water pump and other
accessories
• Must be in good condition and properly
tensioned
© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied,
duplicated, or posted to a publicly accessible website, in whole or in part.
Heater System
• Hot liquid passenger compartment heater is
part of the cooling system
• Air is directed over the heater core and can be
mixed with outside air
© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied,
duplicated, or posted to a publicly accessible website, in whole or in part.
© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied,
duplicated, or posted to a publicly accessible website, in whole or in part.
Cooling Fans
• Cooling system efficiency depends on the
amount of heat that can be removed
• At high speeds ram air is sufficient
• At low speeds an idle air is delivered by a fan
• Mounted very close to the radiator
© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied,
duplicated, or posted to a publicly accessible website, in whole or in part.
Electric Cooling Fans
• Replaced most belt
driven fans
• Controlled by a
temperature switch
and/or air
conditioner switch
via the PCM
© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied,
duplicated, or posted to a publicly accessible website, in whole or in part.
Belt Driven Fans
• May be flex-blade
design
• Fan clutches
uncouple the fan
when not needed
– Temperature
sensitive clutch
– RPM sensitive clutch
© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied,
duplicated, or posted to a publicly accessible website, in whole or in part.
© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied,
duplicated, or posted to a publicly accessible website, in whole or in part.
Hydraulic Fans
• Some vehicles use power steering fluid to
drive the fan
• Fluid is routed into the fan drive based on
cooling requirements
© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied,
duplicated, or posted to a publicly accessible website, in whole or in part.
Temperature Sensors
• Sends signal to PCM for cooling fans
© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied,
duplicated, or posted to a publicly accessible website, in whole or in part.
Temperature Indicator
• Alerts the driver of an overheating condition
• Threaded into a water jacket
• May also supply information to the
on-board computers
© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied,
duplicated, or posted to a publicly accessible website, in whole or in part.
Knowledge Check
• What are three types of cooling fans?
© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied,
duplicated, or posted to a publicly accessible website, in whole or in part.
Cooling System Diagnosis
• Testing for electrolysis in cooling systems
– Current passing through the water separates
hydrogen and oxygen
– Removes the protective layer inside of radiator
tubes
– Caused by improper electrical system grounding
© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied,
duplicated, or posted to a publicly accessible website, in whole or in part.
Inspection of Cooling System
• Most common problem is overheating
• Can be caused by the inability to absorb,
transport, or dissipate heat
• Confirm if engine is overheating
• Use a temperature probe at radiator inlet tank
© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied,
duplicated, or posted to a publicly accessible website, in whole or in part.
Effects of Overheating
•
•
•
•
•
•
Detonation
Preignition
Blown head gasket
OHC cam seizure
Blown hoses
Radiator leaks
• Cylinder damage due to
swelled pistons
• Sticky exhaust valve
stems
• Engine bearing damage
© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied,
duplicated, or posted to a publicly accessible website, in whole or in part.
Temperature Test
• Allows monitoring of temperature changes
• Thermostat opening temperature can be
checked from a cold start
• Probe for cool spots in the radiator
• Cooling fan switch operation can be
monitored
© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied,
duplicated, or posted to a publicly accessible website, in whole or in part.
Radiator Checks
•
•
•
•
Cold spots indicate internal restrictions
Inspect for external restrictions and leaks
Check for loose cooling fins
Salt and road debris can corrode fins and
tubes
© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied,
duplicated, or posted to a publicly accessible website, in whole or in part.
Checking Hoses
• Hoses deteriorate
from the inside
• Upper radiator hose
suffers the most
• Check lower hose
reinforcement spring
© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied,
duplicated, or posted to a publicly accessible website, in whole or in part.
Checking Fans and Fan Clutches
• Inspect fan shroud for fit and damage
• Damage to belt driven fan can damage water
pump and/or radiator
• Check fan clutches for oil loss
• Replace clutch if it spins with little or no
resistance with the engine off
© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied,
duplicated, or posted to a publicly accessible website, in whole or in part.
Electric Cooling Fans
• Check fan, blades, and mounting assembly
• Fan should energize with A/C on and once
engine reaches operating temperature
• If the fan does not come on, jumper the fan
motor to the battery
• Follow the service procedures given by the
manufacturer
© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied,
duplicated, or posted to a publicly accessible website, in whole or in part.
Testing the Thermostat
• Should be
closed when
cold
• Opens when hot
• Most are fully
open at 195° F
(90.5 °C)
© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied,
duplicated, or posted to a publicly accessible website, in whole or in part.
Water Pump Checks
• Noise and leakage are common problems
• Common causes of water pump bearing
failure:
– A bent fan
– A missing piece of fan blade
– A cracked fan blade
– Fan mounting surfaces that are not flush
– A worn fan clutch
© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied,
duplicated, or posted to a publicly accessible website, in whole or in part.
Testing for Leaks
• Most common cause of overheating is low
coolant levels due to leaks
• Hoses, radiator, heater core, water pump,
thermostat housing, freeze plugs,
transmission oil cooler, head gaskets, and
intake gaskets are common leakage points
© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied,
duplicated, or posted to a publicly accessible website, in whole or in part.
Leak Detection with Dye
• Pour dye into
cooling system
• Run engine to
operating
temperature
• With engine off,
inspect with a
black light
© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied,
duplicated, or posted to a publicly accessible website, in whole or in part.
Combustion Leak Check
• Internal leak may be present when there are
no visible external leaks but engine is losing
coolant or hold pressure
• Typically caused by cracked head, head gasket,
or warped head
© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied,
duplicated, or posted to a publicly accessible website, in whole or in part.
Testing the Radiator Cap
• Leaking cap will
reduce boiling
point and cause
an overheating
condition
© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied,
duplicated, or posted to a publicly accessible website, in whole or in part.
Water Outlet
• Can fail from internal corrosion
• Improper torquing can warp or break outlet
© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied,
duplicated, or posted to a publicly accessible website, in whole or in part.
Knowledge Check
• Describe how to perform a cooling system leak
inspection.
© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied,
duplicated, or posted to a publicly accessible website, in whole or in part.
Cooling System Service
• Pressure test the system for leaks
• Check coolant condition and strength using a
hydrometer
• Check radiator cap for proper pressure
• Test thermostat for proper opening and
closing temperatures
© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied,
duplicated, or posted to a publicly accessible website, in whole or in part.
Cooling System Service (Cont.)
• Check hoses for leaks and swelling
• Check the system with a voltmeter for
electrochemical degradation
• Check water pump for bearing failure and
leaks
• Check cooling fans and fan clutch for proper
operation
© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied,
duplicated, or posted to a publicly accessible website, in whole or in part.
Cooling System Service (Cont.)
• Drain coolant below level of hose being
replaced
• Cut end of old hose
• Clean neck of hose fitting
• Dip ends of hose in coolant when installing
• Do not reuse spring clamps
• Install and tighten hose clamps
© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied,
duplicated, or posted to a publicly accessible website, in whole or in part.
Correct Hose Clamp Installation
© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied,
duplicated, or posted to a publicly accessible website, in whole or in part.
Hose Clamps
• Worn drive clamps often replace spring
clamps
• Thermoplastic clamps are shrink fit with a
heat gun
• Readjust a new clamp after a brief run-in
period
© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied,
duplicated, or posted to a publicly accessible website, in whole or in part.
Thermostat
• Always replace with same temperature
• Replace the gasket or seal at same time
© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied,
duplicated, or posted to a publicly accessible website, in whole or in part.
Repairing Radiators
• Repairs depend on radiator construction and
the type of damage
• Most repairs are made by specialty shops
• Plastic tanks are replaced, not repaired
© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied,
duplicated, or posted to a publicly accessible website, in whole or in part.
Replacing the Water Pump
• Drain the cooling system
• Remove parts that interfere with removal
• Loosen bolts in a crisscross pattern from the
center outward
• Follow the procedures given by the
manufacturer
© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied,
duplicated, or posted to a publicly accessible website, in whole or in part.
Draining the Coolant
• Coolant should be
changed every two to
four years
• Drain reservoir and
cooling system
• Never pour coolant into
a sewer or onto the
ground.
© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied,
duplicated, or posted to a publicly accessible website, in whole or in part.
Flushing the Cooling System
• Flush the system when coolant is changed and
when a water pump is replaced
• Power flushing, back flushing, and coolant
exchanges force old coolant out and new
coolant in
• Before using any flush chemical, check to
make sure it is safe for the system
© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied,
duplicated, or posted to a publicly accessible website, in whole or in part.
Refilling and Bleeding
• Refill with correct type
• Determine the total capacity
• Refill system and run engine to operating
temperature
• Remove air trapped in the system
• Refill and recheck coolant level and for any
leaks
© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied,
duplicated, or posted to a publicly accessible website, in whole or in part.
Refilling and Bleeding (Cont.)
• Some engines have air
bleed valves in cooling
system
• Open valves when
refilling system
• Once coolant comes out
of the valve, close the
valve
© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied,
duplicated, or posted to a publicly accessible website, in whole or in part.
Refilling and Bleeding (Cont.)
• Many shops use a
vacuum fill tool
• Vacuum is pulled on
cooling system
• Vacuum draws the new
coolant in and
eliminates air pockets
© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied,
duplicated, or posted to a publicly accessible website, in whole or in part.
Special Procedures
for Hybrid Vehicles
• Require special coolants for engine and
inverter
• Some models use hot coolant storage tanks
• Coolant in the radiator could be cold but hot
in the storage tank
• Follow all manufacturer service and safety
procedures
© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied,
duplicated, or posted to a publicly accessible website, in whole or in part.
Coolant Exchangers
• Removes old coolant and replaces it with new
coolant
• May be air or battery powered
• Normally performed with the engine off
• Flush out coolant before using on next vehicle
if it requires a different coolant
© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied,
duplicated, or posted to a publicly accessible website, in whole or in part.
Knowledge Check
• Technician A says hybrid vehicles may require
special cooling system service procedures.
Technician B says a hybrid vehicle may require
a special coolant for the hybrid system. Who is
correct?
© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied,
duplicated, or posted to a publicly accessible website, in whole or in part.