CH14 lubricating and cooling systems STUDENT VERSION rev

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Chapter 14

Lubricating and Cooling Systems

Lubrication System

• Holds an adequate supply of oil

• Cools and cleans components

• Lubricates parts and reduces wear

• Helps seal the engine

• Removes contaminates

• Delivers oil to necessary areas of engine

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

• Some filters use an anti-drainback valve

• If the filter becomes plugged, a valve opens to allow oil to bypass the filter

Engine Oil Passages or Galleries

• Used to measure the oil level in the oil pan

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

Common External Oil Leaks

• 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

Sludge (cont’d)

• 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

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

Cooling System Components

• 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

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

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

• 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

Hose Clamps

• Designed to apply consistent clamping pressure

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

Electric Cooling Fans

• Replaced most belt

driven fans

• Controlled by a

temperature switch

and/or air conditioner

switch via the PCM

Belt Driven Fans

• May be flex-blade design

• Fan clutches uncouple the fan when not needed

– Temperature sensitive clutch

– RPM sensitive clutch

Temperature Sensors

• Sends signal to PCM for cooling fans

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

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

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

Checking Hoses

• Hoses deteriorate from the inside

• Upper radiator hose

suffers the most

• Check lower hose

reinforcement spring

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

Pressure Testing

• Applies pressure to system for leak test

Leak Detection with Dye

• Pour dye into

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

Testing the Radiator Cap

• Leaking cap will

reduce boiling

point and cause an

overheating

condition

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

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

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

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