LO 11-8 Outline maintenance procedures and identify tools and methods used to perform maintenance on a diesel engine cooling system

Potential Causes of Overcooling
Overcooling is a relatively common complaint that can be caused by several different issues, including:

• A thermostat sticking open
• A blocked thermostat that is leaking
• A malfunctioning temperature gauge
• Fan drives that operate continuously

Potential Causes of Overheating
There are many potential causes of overheating as well. The following are common contributing factors:

• Low coolant
• Blocked or restricted airflow through radiator, air charge cooler, or A/C condenser
• Fan drive not working
• Missing or damaged fan shroud
• Blocked or restricted radiator
• Incorrect radiator cap
• Overconcentrated antifreeze
• Broken, slipping, or damaged water pump impeller
• Over-fueled engine
• High ambient operating temperature
• Over-pressurized cooling system from cracked cylinder head, cavitated block, defective air compressor, etc., pushing coolant out of radiator