Aluminum radiators need extra care

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With aluminum radiators and heater cores becoming common, the National Automotive Radiator Service Association (NARSA) in Pennsburg, Pa., cautions fleet operators that these components require more detailed attention than their traditional, copper/brass counterparts. Aluminum radiators and heater cores provide better heat transfer than copper/brass, says NARSA, and can reduce vehicle weight and packaging requirements. They are susceptible, however, to conditions that are not as critical in traditional systems and can fail if technicians overlook specific maintenance details.

NARSA recommends using a 50/50 mix of organic-acid-technology (OAT) coolant and water; checking the system every two years or 24,000 miles; not mixing coolant types; and adhering to manufacturers’ recommendations.

Two checks technicians are probably not accustomed to making on traditional systems – but which are important for aluminum systems – are pH level and electrolysis.

Incorrect pH levels (too acidic or too alkali) will accelerate cooling system corrosion causing aluminum components to pit and flake. The flakes enter the coolant and remain in suspension until they reach a cooler area, where they drop out and build up until the system is clogged. This is called transport depositing.

A pH reading between 7.7 and 9.3 is considered acceptable.

Electrolysis means there is stray electrical current within the cooling system – often because of poor grounds at major electrical components. Excessive voltage (over 0.1 volts) causes the coolant to become an electrolyte, promoting galvanic corrosion and, often, system perforation.

A low pH level in a system that contains aluminum and one or more other metals exacerbates electrolysis because putting dissimilar metals in an acidic solution is the recipe for a battery. To demonstrate, try pushing a penny and a nickel into half an orange, about an inch apart. You’ll get a voltage reading across the two coins.

To learn more about the proper care of aluminum radiators and heater cores, obtain a NARSA brochure and caution labels. For more information, call (800) 551-3232.