Free Automotive ClassesLesson 6: The Cooling

SystemJeff Crawford

Crawfords Auto Repairwww.CrawfordsAutoService.com

Recall Chapter 5

The Cooling System

The combustion process and movement of mechanical parts both create extreme heat in the engine which must be cooled.

The cooling system keeps the engine temperature within operating range.

(The cooling system is not related to the AC system)

Source: cdxtextbook.com

Major Components of the Cooling System

RadiatorThermostat and HousingWater PumpCooling FanRadiator HosesHeater HosesCoolant

Disney/Pixar’s Cars 2

“Ooh, I’m gonna have to go get myself some coolant!”

Thermostat

The Thermostat opens with heat, due to wax element in the thermostat. The more it opens, the more coolant can pass through.

Image source: How Stuff Works

How the Cooling System Cools

The coolant passes through designated passages throughout the engine (coolant does not mix with other fluids)

Heat transfers to the coolantThe coolant runs to the radiator where

heat is released into the air.

Cooling System Maintenance

Preventative MaintenanceAvoid overheatingAvoid electrolysis (microscopic breakdown

of metals in the engine block)May be needed even sooner than

indicated by the manufacturerLow coolant level may indicate a leak

Cooling System Flush

Steps for Cooling System Flush

Refer to the owner’s manual for locations of each part of the cooling system.

Open the radiator drain to drain the system, collect the drainage in a container.

Remove the thermostat.Disconnect the lower radiator hoseForce coolant through the thermostat

housing, upper hose and engine block with garden hose until water runs clear.

Flush Steps Continued

Connect the garden hose to the radiator, flush until the water runs clear.

Completely drain the cooling system of all water

Reinstall the thermostatDisconnect the reservoir and flush with

garden hose until water runs clear. Completely drain reservoir.Connect the hoses and close the drains.

Flush Steps Continued

Perform a pressure test (next slide)Fill the cooling system with new coolant to

manufacturer’s specification and distilled water. Use 50/50 mixture of coolant and distilled water or pre-mixed coolant

(Distilled water is necessary so you don’t have impurities in the cooling system)

Pressure Test

Connect pressure tester where the radiator cap goes.

Pump pressure to amount specified on the radiator cap.

Leave pressure on for 20-30 minInspect the cooling system for leaksDisconnect pressure tester and connect it

to the radiator cap and pump to specified amount to test the cap

Pressure Testing the Cooling System

Cooling System Pressure Tester

The steps to a cooling system flush and pressure test will all make more sense with our video on YouTube.

Questions?

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