Coolant could be the primary cause of a cooling system failure. What is the condition of the coolant in the system? When a cooling system leaks, air replaces the leaked out coolant. The reaction between the air and the coolant creates a rusty brown substance that clogs up various components.

What to look for?

  • Corrosion is a form of rust that produces aluminum oxide. It appears in the form of a white powder.
  • Corrosion will literally eat away metal surfaces.
  • Electrolysis – There are two types of electrolysis, one is caused by bad electrical connections and grounds. Current for various electrical accessories take a path through the coolant causing electrolysis. The other type occurs because the acidic nature of the coolant and dissimilar metals in the cooling system create a galvanic battery in the cooling system.

Diagnosing electrolysis is easy.

Using a DVOM simply set your meter to DC volts and measure the voltage in the actual coolant. A reading of greater than 0.3 will accelerate the deterioration of the Heater Core and Radiator.

No Matter What the Cause of Failure is – ALL cooling systems must be properly flushed before installing a new Heater Core or Radiator. Failure to flush will void the warranty.

For a detailed education in cooling systems go to the April issue of Motor Age at