chapter 14

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Chapter 14

Lubricating and Cooling Systems


Lubrication System

• Holds an adequate supply of oil

• Lubricates parts and reduces wear

• Delivers oil to necessary areas of engine


Lubrication System (Cont.)

• Cools and cleans components• Helps seal the engine• Removes contaminates


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


• Pickup screen keeps large particles out of the pump

• Oil pressure relief valve prevents excessive oil pressure

Oil Pump


Oil Pan or Sump

• Wet sump always has oil in it – most engine applications are wet sump systems

• Baffles reduce sloshing


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


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


Cartridge Oil Filter


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


Flow Through the Oil Filter


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


Engine Oil Passages or Galleries


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


• 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

Oil Pressure Indicator


Oil Pressure Indicator (Cont.)


Knowledge Check

• Describe the flow of oil in the lubrication system.


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


Engine LubricationDiagnosis 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


Oil Consumption

• External and internal leaks

• Worn piston rings allow blowby

• Worn valve seals or guides


Oil Consumption (Cont.)

• Blue smoke indicates internal leak present

• External leaks occur at gaskets and seals

• Oil usage increases engine wears


Common External Oil Leaks


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


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


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


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


Knowledge Check

• What are three possible causes of oil sludge in an engine?


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


• Thermostat• Water pump• Radiator• Radiator pressure cap• Expansion tank

• Hoses• Water outlet• Water jackets• Cooling fans• Temperature indicators

Cooling System Components


Cooling System Components (Cont.)


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


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


Water Pump (Cont.)


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


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


Radiator Cap

Pressure operation

Vacuum operation


• Designed to catch and hold coolant passing from radiator cap as the coolant expands

Expansion Tank


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


Knowledge Check

• What is the purpose in allowing pressure to increase in the cooling system?


Water Outlet

• Connects the engine and upper radiator hose• Also called a gooseneck, elbow, inlet, outlet,

or thermostat housing• May cover thermostat


Water Jackets

• Surround combustion chambers• Some engines use plastic inserts to direct

coolant flow within the jacket• Includes core plugs and block drain


Water Jackets


Hose Clamps

• Designed to apply consistent clamping pressure


Belt Drives

• Used to drive the water pump and other accessories

• Must be in good condition and properly tensioned


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


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


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


Hydraulic Fans

• Some vehicles use power steering fluid to drive the fan

• Fluid is routed into the fan drive based on cooling requirements


Temperature Sensors

• Sends signal to PCM for cooling fans


Temperature Indicator

• Alerts the driver of an overheating condition• Threaded into a water jacket• May also supply information to the

on-board computers


Knowledge Check

• What are three types of cooling fans?


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


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


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


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


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


Testing the Thermostat

• Should be closed when cold

• Opens when hot• Most are fully

open at 195° F (90.5 °C)


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


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


Leak Detection with Dye

• Pour dye into cooling system

• Run engine to operating temperature

• With engine off, inspect with a black light


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


Water Outlet

• Can fail from internal corrosion• Improper torquing can warp or break outlet


Knowledge Check

• Describe how to perform a cooling system leak inspection.


• 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

Cooling System Service


• 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

Cooling System Service (Cont.)


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


Correct Hose Clamp Installation


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


Thermostat

• Always replace with same temperature• Replace the gasket or seal at same time


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


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


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


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


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


Special Proceduresfor 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


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


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?

chapter 14

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