GM Service Manual Online
For 1990-2009 cars only

Radiator Restrictions

A dirty, obstructed, or leaking radiator core causes overheating. Scale deposits result from using hard high-mineral water in the cooling system. Heating these minerals causes the formation of a hard coating on the surfaces within the radiator. Scaling reduces the transfer of heat. Some hard water produces a silt-like deposit that restricts the flow of water. A radiator that is partially restricted should be removed and cleaned by a radiator repair specialist. Replace a radiator core that is plugged or has a heavy scale.

Flushing Procedure

Important: 

   • Remove the coolant thermostat before flushing the cooling system. Refer to Engine Coolant Thermostat Replacement .
   • Dispose of the used engine coolant properly.
      - Store the used engine coolant in a used coolant holding tank, while awaiting approved disposal methods.
      - Do not pour used engine coolant down the drain.
         • 
   • Dex-Cool® antifreeze is a very toxic chemical.
         • 
   • Disposal into a sewer system or contaminating the ground water is both environmentally irresponsible and illegal.

There are different methods to flush the cooling system. Back flushing is recommended. Special equipment is available. Follow the equipment manufacturer's instructions for use.