DEFINITION: The cooling system is losing coolant either internally or externally.

Inspect the coolant level.

Is the coolant at the correct level?

Go to Step 6

Go to Step 4

Fill the cooling system to the correct level. Refer to Cooling System Draining and Filling .

Is the action complete?

Go to Step 5

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If the engine is suspected to have a coolant leak into a cylinder, the coolant can hydraulically lock the engine.

Does the engine crankshaft rotate?

Go to Step 6

Repair the engine no crank condition. Refer to Engine Will Not Crank - Crankshaft Will Not Rotate or Engine Will Not Crank - Crankshaft Will Not Rotate

Engine overheating can cause a loss of coolant.

Is the engine overheating?

Repair the engine overheating condition. Refer to Engine Overheating

Go to Step 7

Extended operation with a low coolant level can cause engine internal component failure.

Is the engine knocking?

Repair the engine knock. Refer to Lower Engine Noise, Regardless of Engine Speed and Lower Engine Noise, Regardless of Engine Speed .

Go to Step 8

1. Idle the engine at normal operating temperature.
2. Inspect for heavy white smoke coming out of the exhaust system.

Is a heavy white smoke present from the exhaust pipe?

Go to Step 9

Go to Step 10

Coolant in the exhaust system creates a distinctive, burning coolant odour in the exhaust.

Condensation in the exhaust system can cause an odourless white smoke during engine warm up.

Does the white smoke have a burning coolant type odour?

Repair the engine internal coolant leak. Refer to Coolant in Combustion Chamber or Coolant in Combustion Chamber .

Refer to Coolant in Engine Oil or Coolant in Engine Oil

Go to Step 10

With the engine idling, inspect the coolant recovery reservoir.

Does the coolant recovery system discharge coolant while the engine is idling?

Repair the engine internal coolant leak. Refer to Coolant in Combustion Chamber or Coolant in Combustion Chamber .

Refer to Coolant in Engine Oil or Coolant in Engine Oil .

Go to Step 11

Visually inspect the hoses and hose retaining clamps at the following locations:

Are any of the hoses leaking.

Repair or replace the leaking component. Refer to the appropriate repair.

Go to Step 12

Visually inspect the following components:

Are any of the listed components leaking?

Repair or replace the leaking component. Refer to the appropriate repair.

Go to Step 13

1. Pressure test the cooling system. Refer to Cooling System Leak Testing .
2. With the cooling system pressurized, visually inspect the components listed in steps 11 and 12.

Are any leaks present?

Repair or replace the leaking component. Refer to the appropriate repair.

Go to Step 14

Pressure test the coolant pressure cap. Refer to Pressure Cap Testing .

Does the coolant pressure cap hold pressure?

Go to Step 13

Replace the coolant pressure cap.

Inspect for the following conditions:

Is coolant present?

Replace the heater core. Refer to Heater Core Replacement .

Go to Step 15

Inspect the underside of the engine oil fill cap for a gray/white milky substance.

Is there a milky substance on under the oil fill cap?

Repair the engine internal coolant leak. Refer to Coolant in Combustion Chamber or Coolant in Combustion Chamber .

Refer to Coolant in Engine Oil or Coolant in Engine Oil .

Replace the coolant pressure cap.

Inspect the engine oil level indicator for a gray/white milky substance.

Is there a milky substance on the engine oil level indicator?

Repair the engine internal coolant leak. Refer to Coolant in Combustion Chamber or Coolant in Combustion Chamber .

Refer to Coolant in Engine Oil or Coolant in Engine Oil

Replace the coolant pressure cap.