GoodheartWillcox Co Inc Cooling system diagnosis Cooling system

© Goodheart-Willcox Co. , Inc.

§ § § § Cooling system diagnosis Cooling system problems Thermostat service Cooling system hose service Radiator and pressure cap service Fan belt service Coolant service Flushing a cooling system © Goodheart-Willcox Co. , Inc.

§ Gather information: § talk to the owner or service writer to find out as much as possible about the symptoms § diagnosis charts in the service manual can be very helpful © Goodheart-Willcox Co. , Inc.

On-Board Diagnostics § Cooling-related problems may set a diagnostic trouble code on some systems § § © Goodheart-Willcox Co. , Inc. use a scan tool to analyze the system MIL lamp may be on data will indicate engine temperature even failure to bleed a system of air could cause erratic temperature sensing

Inspecting Cooling System § Perform a visual inspection for: § § § § © Goodheart-Willcox Co. , Inc. coolant leaks loose or missing fan belts low coolant level water pump noises plugged radiator fins coolant in the oil (oil looks milky) combustion leakage into coolant

Common Problems © Goodheart-Willcox Co. , Inc.

§ Coolant leaks § Overheating § Overcooling © Goodheart-Willcox Co. , Inc.

Coolant Leaks § External leaks § most common § show up as wet, discolored areas on parts § Internal leaks § caused by cracked block, head or blown head gasket © Goodheart-Willcox Co. , Inc.

Cooling System Problems A blown head gasket can allow combustion gases to enter the coolant © Goodheart-Willcox Co. , Inc.

Cooling System Problems Mineral deposits in water jackets can prevent proper heat transfer © Goodheart-Willcox Co. , Inc.

Cooling System Problems A cracked part or blown gasket can allow coolant to leak into the engine oil © Goodheart-Willcox Co. , Inc.

Cooling System Pressure Test § Low air pressure is forced into the system § causes coolant to pour or drip from any leak § Install pressure tester on filler neck § Pump the tester to pressurize system § Maximum 14 psi, (96 k. Pa) or cap rating © Goodheart-Willcox Co. , Inc.

Cooling System Pressure Test © Goodheart-Willcox Co. , Inc.

Combustion Leak Test § Checks for the presence of combustion gases in the coolant § Place combustion leak tester on filler neck § Start engine and squeeze tester bulb, pulling air through test fluid § If combustion gases are present in the radiator, fluid changes color © Goodheart-Willcox Co. , Inc.

Combustion Leak Test Combustion leakage can make the engine overheat © Goodheart-Willcox Co. , Inc.

Causes of Overheating § § § § Low coolant level Rust or scale accumulation in water jacket Stuck thermostat Delayed ignition Loose fan belt Bad water pump or collapsed lower hose Missing fan shroud or fan problems Causes of Overcooling §Stuck thermostat (open) §Locked fan clutch §Shorted fan switch © Goodheart-Willcox Co. , Inc.

§ A bad pump may leak, fail to circulate coolant, or produce a grinding sound § Causes: § rust in the cooling system § lack of coolant § overtightened belts © Goodheart-Willcox Co. , Inc.

§ A stuck thermostat can cause engine overheating or overcooling § Stuck open–overcooling § loss of efficiency, power, mileage § high emissions § Stuck closed–overheating § engine damage © Goodheart-Willcox Co. , Inc.

Thermostat Testing § Watch the coolant through the opening in the radiator neck § Cold engine, coolant should not flow § Hot engine, coolant should begin to circulate past the opening § Use a digital thermometer to monitor the temperature of thermostat housing © Goodheart-Willcox Co. , Inc.

Thermostat and Housing © Goodheart-Willcox Co. , Inc.

Thermostat Replacement © Goodheart-Willcox Co. , Inc.

Thermostat and Housing Special O-ring seal should be replaced anytime thermostat is removed © Goodheart-Willcox Co. , Inc.

Bleeding the Cooling System § A bleed valve is sometimes provided § Cars with low hood lines require a bleed screw to empty air pockets § Trapped air can cause overheating or damage from hot spots (buildup of heat) © Goodheart-Willcox Co. , Inc.

Bleeding the Cooling System § Fill the system § Start and warm the engine § Crack open the bleed screw until all air is purged from the system § NEVER remove a cooling system bleed screw or any clamp on a hot, pressurized system!!! © Goodheart-Willcox Co. , Inc.

Bleeding the Cooling System © Goodheart-Willcox Co. , Inc.

Common Hose Problems Hoses deteriorate and become soft and mushy or hard and brittle © Goodheart-Willcox Co. , Inc.

Hose Replacement A. Loosen clamp, twist and pull hose off B. Clean fitting C. Install new hose and clamp, check for leaks © Goodheart-Willcox Co. , Inc.

© Goodheart-Willcox Co. , Inc.

Inspecting the Radiator and Pressure Cap § Inspect radiator fins for debris and rot § Make sure the shroud is in place § Perform pressure cap test § measures cap opening pressure § checks sealing washer condition © Goodheart-Willcox Co. , Inc.

Pressure Testing a Radiator Cap © Goodheart-Willcox Co. , Inc.

Radiator Removal © Goodheart-Willcox Co. , Inc.

§ A loose fan belt will slip and squeal § may cause overheating § Inspect the condition and tension § Use a belt tension gauge to adjust belts § A faulty fan cause overheating, overcooling, vibration and water pump damage § Check for bent blades, cracks or fluid leakage © Goodheart-Willcox Co. , Inc.

Coolant should be checked and changed at regular intervals § Breaks down and becomes acidic § Rust preventative properties are lost © Goodheart-Willcox Co. , Inc.

Changing Coolant © Goodheart-Willcox Co. , Inc.

Checking Coolant Level Coolant should be even with correct marking on reservoir © Goodheart-Willcox Co. , Inc.

Checking Coolant Level Coolant should be 1” below the top of the tank © Goodheart-Willcox Co. , Inc.

Testing Coolant Strength § Measures the concentration of antifreeze compared to water § Determines freeze protection § Tool used: § cooling system hydrometer © Goodheart-Willcox Co. , Inc.

Hydrometer When filled, pointer will float to indicate freeze protection © Goodheart-Willcox Co. , Inc.

§ Cleans rust and scale from the system § May involve running a cleaning chemical through the system § Three Methods: § 1. fast flushing § 2. reverse flushing § 3. chemical flushing © Goodheart-Willcox Co. , Inc.

1. Fast Flushing © Goodheart-Willcox Co. , Inc.

2. Reverse Flushing © Goodheart-Willcox Co. , Inc.

3. Chemical Flushing § Used when scale buildup is causing overheating § Chemical cleaner is added to the coolant § Engine is operated for a specific amount of time § System is flushed with water © Goodheart-Willcox Co. , Inc.