Along with the evolution of the motor vehicle over the years have come various advances in vehicle technology, driven by a growth in manufacturer capabilities, customer demand as well as the need to produce vehicles which are more efficient. Some aspects of this advancement included new possibilities to reduce the weight of the vehicles as well as an increased use of electronics while still maintaining the costs of the vehicles within desired parameters. Along with these changes came the use of aluminium heat exchangers in place of the old copper brass parts that were used in years gone by. This led to an entirely new set of challenges in terms of cooling system maintenance, one of which is the occurrence of electrolysis. As long as the vehicles electrical systems are operating normally this problem does not occur but if it does happen at some point that there is a malfunction or a substandard repair on an electrical system then it is likely that this problem will surface and it is the objective of this article to impart an understanding of how this occurs and why it causes a radiator or heater to fail, sometimes within a very short space of time.
The process that takes place between the radiator or heater during electrolysis can be visualized by picturing what happens in the battery of your vehicle. Inside the battery there are metal plates of differing material, each one being connected to its respective battery pole i.e the positive or negative pole. Inside the battery casing there is an electrolyte which takes part in the chemical reactions taking place inside the battery. When there is a current flow across the poles of the battery there are certain chemical reactions inside the battery which drive this. At the negative pole there will be an oxidation reaction taking place while at the positive pole there will be a reduction reaction taking place. What happens during an oxidation reaction is that metal is taken from the surface of the plate and converted to an oxide. This process depletes the material at the negative pole of the vehicles battery. In the case of a vehicle battery however this process can be reversed when the battery is recharged. The same does not happen during electrolysis of the vehicles cooling system components.
In the case of the cooling system there are differing metals and alloys used in the radiator, heater and even the water pump as opposed to the materials used in the engine block etc. These materials are in electrical contact with each other via the engine coolant which will act as a conductor and an electrolyte. The different materials at the points mentioned will act as a positive and negative pole of a battery under the right conditions. As soon as there are stray currents generated in the vehicles electrical system e.g. when there is a bad earth in an electrical circuit, these currents will cause a reaction in the cooling system in the same way as what happens in the vehicles battery. An oxidation reaction is set off which will oxidize the aluminium components in the cooling system and because the radiator and heater have the thinnest material thicknesses these will usually be the first to fail when the oxidation process has removed enough material from the metals surface.
This type of failure can happen in both petrol as well as diesel vehicles. When a cooling system component fails it is important to find out the reason for this. If this is not done simply replacing the radiator will not solve the problem and a new radiator could fail in the space of only a few days or in really severe cases in a matter of hours. Of course such a radiator or heater cannot be covered by a warranty because without removing the cause of failure the warranty conditions will not be satisfied. For this reason it is vitally important to make sure that a radiator or heater installation is done by a professional who knows what they are doing. In this way you will have peace of mind that your vehicle will be back in tip top condition for trouble free motoring.