Cooling System - overheating, low coolant, refilling, flushing, and more

General Auto Repair

The automotive cooling system consists of a radiator, water pump, thermostat, electric or belt-driven cooling fan, pressure cap, heater, and various connecting hoses and cooling passages in the engine block and cylinder head.

DRAINING

Remove radiator cap and open heater control valve to maximum heat position. Open drain cocks or remove plugs in bottom of radiator and engine block. In-line engines usually have one plug or drain cock, while "V" type engines have 2, one in each bank of cylinders.

FLUSHING

Some automotive manufacturers use an aluminum and plastic radiator. Flushing solution must be compatible with aluminum.

• Radiator - Connect flushing gun to water outlet of radiator. Disconnect water inlet hose. To prevent flooding engine, use a hose connected to radiator inlet. Use air in short bursts to prevent damage to radiator. Continue flushing until water runs clear.

• Engine Block - To flush engine, remove thermostat. Connect flushing gun to water outlet of radiator. Use air in short bursts to prevent damage to radiator. Continue flushing until water runs clear.

REFILLING

To prevent air from being trapped in engine block, engine should be running when refilling cooling system. After system is full, continue running engine until thermostat is open, then recheck fill level. Do not overfill system.

TESTING

1. Remove and inspect thermostat for corrosion and proper seating of valve. If okay, suspend thermostat and thermometer in a 50/50 mixture of coolant and water. DO NOT allow thermostat or thermometer to touch bottom or container. Heat water until thermostat begins to open.
2. Read temperature on thermometer. This is the initial opening temperature and should be within specification. Continue heating water until thermostat is fully open and note temperature. This is the fully open temperature. If either reading is not to specification, replace thermostat.

PRESSURE TESTING

A pressure tester is used to check both radiator cap and complete cooling system. Follow pressure tester manufacturer instructions and test components as follows:

Visually inspect radiator cap. If cap looks okay, connect pressure tester to cap. See Fig. 2 . Pressurize tester to full radiator cap specification. Replace cap if it fails to hold pressure.

1. Turn ignition off and allow engine to cool. Ensure radiator if filled to correct level. Remove cap and attach pressure tester to radiator. Pressurize tester to full radiator rating specification.
2. If pressure drops, check for external leaks. If no leaks are found, start engine and allow to idle. If pressure builds up immediately, check cylinder head and block for cracks. If pressure does not build up immediately, go to next step.

FYI: DO NOT allow excess pressure to build in cooling system or damage may result.

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Troubleshooting the Cooling Systen

The general trouble shooting information lists common vehicle symptons with possible solutions and is not for any particular vehicle make and model. For repair info specifically for your make and model please view the main directory.

Overheating

• Coolant Leak: Fill/Pressure Test System
• AC Condenser Fins Clogged: Remove/Clean Condenser
• Radiator Fins Clogged: Remove/Clean Radiator
• Thermostat Stuck Closed: Replace Thermostat
• Clogged Cooling System Passages: Clean/Flush Cooling System
• Water Pump Malfunction: Replace Water Pump
• Fan Clutch Malfunction: Replace Fan Clutch
• Retarded Ignition Timing: Reset Ignition Timing
• Cooling Fan Malfunction: Test Cooling Fan/Circuit
• Cooling Fan Motor Malfunction: Test Fan Motor
• Cooling Fan Relay Malfunction: Test Fan Relay
• Faulty Radiator Cap: Replace Radiator Cap
• Broken/Slipping Fan Belt: Replace Fan Belt
• Restricted Exhaust: Repair Exhaust System

Corrosion

• Impurities In Coolant: Clean or Flush System

Coolant Leakage

• Damaged hose: Replace Hose
• Leaky Water Pump: Replace Water Pump
• Damaged Radiator Seam: Replace or Repair Radiator. Do not use radiator quick-fix fillers which will corrode and shorten the life span of your water pump.
• Leaky Thermostat Cover: Replace Thermostat Cover
• Cylinder Head Problem: Check Head and Head Gasket
• Leaky Freeze Plugs: Replace Freeze Plugs

Recovery System Inoperative

• Loose and/or Defective Radiator Cap: Replace Radiator Cap
• Overflow Tube Clogged and/or Leaking: Repair Tube
• Recovery Bottle Vent Restricted: Clean Vent

No Heater Core Flow

• Collapsed Heater: Hose Replace Heater Hose
• Plugged Heater Core: Clean/Replace Heater Core
• Faulty Heater Valve: Replace Heater Valve

General Automotive Repair

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