How galvanic corrosion affects your car repairs

Galvanic corrosion affects nuts and bolts and your coolant

Galvanic corrosion occurs when two or more dissimilar metals are in physical contact with one another or in contact with a conductive liquid (electrolyte). In simple terms, Galvanic corrosion is the movement of electrons and ions from one metal to the other.

Galvanic corrosion occurs in all areas of a vehicle

You’ll find galvanic corrosion in all areas of a vehicle; nuts and bolts, suspension components, body panels, steering, bearings—anywhere where two dissimilar metals touch or can come in contact with a conductive liquid like salt water from the road.

Galvanic corrosion can even happen in the cooling system

Fresh engine coolant contains anti-corrosion additives that prevent the coolant from becoming conductive, even though the coolant is in constant contact with many dissimilar metals like:

• aluminum (engine, water pump, radiator, heater core,
• brass (thermostat),
• steel (metal heater hoses),
• copper (heater cores)
• alloys

However, once the anti-corrosion additives wear out, coolant becomes a fairly good conductor/electrolyte and then galvanic corrosion begins.

How the corrosion happens

Dissimilar metals and alloys have different electrode potentials. When two or more come into contact in an electrolyte, one metal (the metal that is more reactive) becomes the anode and the other becomes the cathode.

It’s the electropotential difference between the two metals that drives the movement of ions from the anode to the cathode causing the anode to corrode.

Galvanic corrosion is just a different type of corrosion

If you leave steel out in the open, moisture causes it to rust. This is caused by oxidation, which is why rust is called iron oxide. But galvanic corrosion needs an electrolyte to operate.

Worn out coolant cause cost you thousands

Once your coolant loses its protection, the corrosion will eat away at the metals in the radiator and heater core, causing pinhole leaks. Radiator replacement can easily cost upwards of $600- $800 and replacing a heater core usually requires the complete disassembly of the dash, costing $1,500 or more.

You can test the conductivity of your coolant with a multimeter

Follow the test instructions posted in this article to check the conductivity of your coolant.

©, 2023 Rick Muscoplat