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Flashcards in cooling systems part 2 Deck (25):

two most common problems with cooling systems

to hot
to cold


first thing to check when trouble shooting cooling systems

coolant level


visual inspection of rad core

check for dirt a debris build up
bent tubes and fins


bent fin repair

bent fins can be repaired with a fin comb


when using compressed air to clean a rad

use low pressure
90 degrees to rad tubes and fins
keep nozzle safe distance away from tubes and fins


coolant leak checks

check for coolant puddles under unit
pressure cap may be malfunctioned or wrong cap


drive belt that is to loose will cause

water pump will not be able to drive as fast and consistently as required


drive belt that is to tight

pre mature wear of bearings on water pump shaft resulting in seal and bearing damage


excessive end play at one assembly equipped with a drive pulley

may cause the drive belt to wear uneven or fly of the pulleys


when checking cooling fans

always check when engine is shut down


when observing moving fan assembly

always stand in front or behind never stand beside or parallel with moving fan
fan blades have been known to fly off and kill techs


when removing pressure cap off rad

always cover with a heavy rag or cloth
wear gloves and keep face towards the side
remove cap slowly


when pressure testing rad

use pressure no more than 10% of rated cap psi
check for external leaks
dye can be placed in cooling system for ease of detection


if no external leaks but psi keeps dropping

an internal leak may be the cause


two indications of internal cooling leak

white smoke out exhaust
dipstick may have frothy white contamination


when testing electric temp gauge on unit

unit must be done with unit running
install a known accurate temperature sensing instrument to confirm accuracy of vehicle instrument


when trouble shooting fan clutch

fan clutch troubleshooting chart should be used


visual inspection of shutter system

check for smooth operation of linkage
lines in good condition


when draining coolant

make sure unit I on a level surface
proper container is used for reuse or recycle


testing thermostat for proper operation

once removed thermostat should be closed at room temp
place in a container of water and slowly heat and record the tamp thermostat opens


when should thermostats start to open

within 1 degree of stamped temp and should be fully open within 12 degrees of temp


when installing thermostat

make sure temp sensing portion is facing the engine


when inspecting water pump you should pay close attention to

impellers and drive gear


when removing impeller on a water pump

use a puller and never hammer or pry on them
made from cast and can brake easy


when flushing coolant system it is good practice to

flush engine block first as coolant passages are larger and debris can be stuck in smaller cooling passage ways in rad