Why is My Radiator Leaking? - Radiator Failures, Leaks and Electrolysis

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Have you had your aluminum radiator or core leak, then replaced or repair it, only to see it start leaking again within year? Have you had a radiator fail from the inside out due to corrosion or pitting? What about having coolant leaking from the heater core, and the appearance of small black pinholes anywhere on the heater core? Or even a gradual loss of coolant? If you've noticed any of these issues you might be asking yourself, "Why is my radiator leaking?."

Well, any or all of these cooling system failures are tell-tale sign of a common cooling system malfunction know generally as Electrolysis.


Electrolysis is a chemical reaction that takes place between the coolant and metal surfaces and is the result of electricity flowing through your cooling system; causing an electrochemical charge across the aluminum. This can result in the rapid deterioration and corrosion of the components of your aluminum cooling system. Electrolysis can be extremely corrosive, very quickly. If present, it will eat away at the inside linings of a aluminum radiator, usually at the weakest points such as seams and welds. There are actually two different types of electrolysis that can happen in an aluminum radiator, but more often than not; a combination of these factors contribute to rapid deterioration of your radiator:

1. Chemical Electrolysis- This happens when a cooling system has a chemical imbalance due to a foreign mix of metals in the radiator. A mixture of different metals and minerals in a cooling system can actually create electricity, much like a chemical car battery. Water with high trace elements of minerals will create problems for aluminum radiators not normally seen in copper radiators. This can be due to several factors:

  • Not using a Waterless Coolant or using a 50/50 mix of coolant and NON distilled water (distilled water has no minerals in it)
  • Recycling antifreeze or not properly cleaning and changing old antifreeze
  • Lack of maintenance

2. Stray Voltage Electrolysis- When a stray electrical charge from an electrical component is coursing through the radiator (as well as the coolant) and is grounded by the aluminum. Since aluminum is the softest material in the system, this can lead to rapid deterioration of the radiator. Several factors can contribute to stray voltage Electrolysis:

  • Bad grounds or broken/loose/frayed wires
  • Electric components not properly installed or grounded
  • Alternator over charging
  • Grounding electrical components to the car frame and then mounting the radiator to the frame.

The best method for avoiding electrolysis damage with your High Performance, Wizard Cooling Aluminum Radiator is to be proactive with maintenance of your cooling and electrical systems. ALWAYS ensure that the radiator is not being used as the ground or inadvertently being grounded by other means. Make sure that all electrical component are properly installed and insulated.

We also recommended using a high performance, water less coolants like EVANS NPG Waterless Engine Coolant to avoid the addition of foreign minerals from a water source. It is also important to change your coolant to ensure old coolant (which can be corrosive) doesn't slowly erode the aluminum.

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