Wear and Breakage

• Over time, gaskets, hoses and lines can soften, dry and wear out. Any loss of system pressure or collapse under negative pressure can cause overheating under extreme usage.
  
  

Thermostat

• The wax pellet found in the engine's thermostat can wear out and lose its ability to open the valve over time, and the valve itself can become stiff and stick. Replacement of the engine's thermostat every 150,000 to 200,000 miles is recommended.
  
  

Inadequate Cooling

• Modifying an engine to produce more power also produces more heat. Replacement of the radiator, water pump and coolant tubes with more efficient units is recommended.
  
  

Blocked Coolant Lines

• Older Chevrolet radiators are notorious for rusting from the inside out, particularly when antifreeze has been excluded from the coolant for a long period of time. Rust scale from the radiator can break loose and lodge itself in the small coolant passages in the heads.
  
  

Broken Components

• Repeated heat cycling and overheating can result in cracked engine blocks and heads, both of which will cause overheating.