Check the coolant for proper concentration level. Refer to Coolant Concentration Testing .

Is the coolant concentration level within specification?

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Go to Step 3

Go to Step 2

1. Drain the cooling system. Refer to Cooling System Draining and Filling .
2. Flush the cooling system, if necessary. Refer to Flushing .
3. Refill the cooling system with a 50/50 mixture of DEX-COOL® coolant and clean, drinkable water. Refer to Cooling System Draining and Filling .

Is the repair complete?

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Go to Step 7

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Check the thermostat to see if it is in a stuck open position. Refer to Thermostat Diagnosis .

Is the thermostat stuck open?

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Go to Step 4

Go to Step 5

Replace the thermostat. Refer to Engine Coolant Thermostat Replacement .

Is the repair complete?

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Go to Step 7

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Check the coolant level.

Is the coolant level below the add mark?

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Go to Step 4

System OK

Add the coolant as necessary. Use the proper fluid. Refer to Fluid and Lubricant Recommendations in Maintenance and Lubrication.

Is the repair complete?

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Go to Step 7

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Verify proper system operation.

Is the engine slow to warm up, does not reach normal operating temperature or does not have enough heat?

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Go to Step 1

System OK