| Cause | Correction | |
| Malfunctioning temperature sensor/gage |
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Verify that the gage and temperature sensor are accurate. |
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| Malfunctioning, incorrect or no thermostat |
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Check/replace the thermostat. |
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| Air in the cooling system |
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Make sure the fill rate is not being exceeded and the correct vented thermostat is installed. |
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If aeration continued, check for a compression leak through the head gasket. |
| Malfunctioning water pump |
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Check/replace the water pump. |
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| Incorrect injection pump timing |
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Check/time the injection pump. |
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| Incorrect external injection pump timing |
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Verify pump timing marks are aligned. |
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| Overfueled injection pump |
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Replace the injection pump. |
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| Plugged cooling passages in radiator, head, head gasket or block |
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Flush the system and fill with clean coolant. |
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| Engine overloaded |
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Verify that the engine load rating is not being exceeded. |