"Generally you won't know you have an electrolysis problem unless you have (a series of) unexplained leaks."

Electrolysis 101

What is electrolysis and why is it a problem in an automotive cooling system? Lets start by trying to understand electrolysis as it pertains to automobiles. Electrolysis is a destructive force that packs enormous potential to damage not just cooling system components, but to any aluminum engine part that has contact with the coolant. There are 2 distinct types of electrolysis, one caused mostly by improper grounding issues, called Type A, and the other primarily due to the chemistry of the coolant, called Type B. In a nutshell, if your electrolysis goes away when the battery is disconnected, you have Type A. If your electrolysis remains, you have Type B.

Let's Run a test.

Type A electrolysis involves an incomplete circuit, typically  a ground, that uses the coolant as a return path. This type of electrolysis is generally easy to isolate by pulling fuses, unplugging harnesses, adding grounds, etc. To establish the presence of Type A electrolysis, removal of a battery cable at the post is necessary.

Lets learn more about Type A electrolysis.

Type B electrolysis is similar to the dynamic of a battery. The coolant acts as a catalyst and allows and encourages ion movement, just like the electrolyte in a battery. The "electrodes" defined at the top of this page, are the aluminum components in the cooling system (like the lead plates in a battery). The coolant is literally infected. 

Lets learn more about Type B electrolysis.

Generally you won't know you have an electrolysis problem unless you have (a series of) unexplained leaks. However, to add yet another factor, in some parts of the country (southwest), electrolysis is much more prevalent than others. Electrolysis will manifest itself with unexplained coolant leaks in thin walled aluminum components, typically the heater or radiator, whichever may be more "electrically attractive" to the ion movement. Recent research suggests that the actual spot of the damage in a heater or radiator is influenced by the distance to the metals that are the cathode (the engine). It is suggested that even though new parts are installed, the distance is the same, and explains why the aluminum parts fail in the same places over and over.

Can Electrolysis be prevented? Absolutely! It has been said an ounce of prevention is worth a pound of cure, this could not be more true! The key to the prevention of Type B electrolysis simply means not letting the coolant wear out. When the corrosion inhibitors in the coolant wear out, were just begging  for electrolysis to start. Change the coolant every 2 years. Easy.

There are plenty of good uses for electrolysis, such as in the plating industry, where the goal is to move metal particles from one surface to another. Gold plated emblems and jewelry are successful applications of electrolysis. Of course another type of electrolysis is hair removal. Industrial applications of electrolysis include the manufacture of aluminum, and lithium, and hydrogen for hydrogen fuel cell vehicles. Other commercial applications include the manufacture of aspirin. But in an automobile cooling system, the presence electrolysis will only give us a headache!

If electrolysis has always been around, why is it such a big problem now? It used to be that the difficult electrical problems consisted of shorts, opens, and draws. With high tech cars, we have to worry about reference voltage, voltage feedbacks, bus speed, thermo resistors and variable grounds. Secondary spark voltages are only increasing, A/C and D/C currents and EFI signal amplitudes add an aggressive neutron and proton cocktail where water (coolant) conducts electricity by the movement of ions in the increasingly at-risk cooling system. In an unprotected cooling system these neutron and proton atoms magnify the strength of the electrolyte infected coolant. With more and more aluminum components under the hood and in the cooling system, longer maintenance cycles and more stray electrical energy, no wonder it's a problem!²

Type A Electrolysis | Type B Electrolysis | How to Flush

2 BMR Distributing Interject Electrolysis Arrestor.