- Generally you won't know you have an electrolysis problem unless you have (a series of) unexplained leaks.
- Electrolysis will manifest itself with coolant leaks in thin walled aluminum components
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.
- Type A electrolysis involves an incomplete circuit, typically a poor 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.
- 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", are the aluminum components in the cooling system (like the lead plates in a battery). The coolant is literally infected, allowing and encouraging ion movement.
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 as pie.
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 feedback's, bus speed, thermo resistors, voltage dividers, and variable grounds. Secondary spark voltages are only increasing, A/C and D/C currents and EFI signal amplitudes can 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, it's no wonder it's a problem.
Testing for Electrolysis
Can Electrolysis be measured? At the heart of any electrolysis discussion is it's measurement. If it can be measured, it's presence can be verified, which is extremely important when we are classifying, treating, and removing the electrolysis. To get started, lets take a couple of simple measurements, with a digital VOM (volt/ohm meter).
1) Simply attach the negative lead of the voltmeter to the engine block, or other known good ground, and with the positive lead, dip it in the coolant. Unless you read zero, you have electrolysis. If you measure less than .1v, your cooling system should be below the action level. If you measure .2v or above, keep reading.
2) Next, repeat the test with the positive battery cable removed. Still reading .2v or above? It's not a loose ground your after....the voltage is coming from within, and you most likely have type B electrolysis.
If your voltage dropped when battery was disconnected, you most likely have type A electrolysis. Type A may be isolated to a switched circuit, and must be isolated in much the same manner as finding a voltage draw: circuit by circuit. It may just be a loose or missing ground. It may be much more.
Regardless, if you have a reading of more than .2v, (two tenths), you may have damaging electrolysis.
- Generally, a reading of hundredths (.01-.09v) is below the action level, and will not result in aluminum failure.
- Aluminum damage will begins to occur at .3v
- "When the antifreeze/coolant wears out, it acts like the acid in a battery, allowing dissimilar metals to react, and create a voltage."
2) An electrochemical process by which electrical energy is used to promote chemical reactions that occur at electrodes.
Type B electrolysis is similar to the dynamic of a battery. The coolant acts like a catalyst and allows and encourages ion movement, just like the electrolyte in a battery. The "electrodes" defined above, are the aluminum components in the cooling system (like the lead plates in a battery). The "electrochemical process" mentioned is the aluminum particle (ion) movement, such that leaks (thinning of wall surface) occur. When enough ions have moved, this results in a failure (leak) typically in the radiator or heater due to the thinness of the tube wall surface. A thicker surface (like an aluminum casting) is not more resistant to electrolysis, but is not as likely to leak because it is thicker. However these thicker surfaces may leak anyway if the electrolysis occurs at a gasket surface.
When the coolant gets acidic will it act like an electrolyte, and set the stage is set for electrolysis to occur, and the destruction of thin aluminum components to begin. So how does coolant get acidic? Up until the mid '90's, the recommended service interval for coolant was 24 months. When changed at this interval, the coolant was removed before it was "spent". It still had good color and was still protecting the metals with corrosion inhibitors. When changed, all the old coolant mix was purged, along with any small amounts of acidic build up. As a result, Type B electrolysis in the early 90's was extremely rare. Beginning in 1996, with GM's introduction of Dex-cool, the recommended service interval of coolant grew to 5 years. GM wasn't the only automaker to use longer life coolants. New developments in coolant chemistry and a changing maintenance strategy has fueled these advances that are tested in laboratory conditions and on vehicle fleets. Unfortunately the successes in the laboratory have not always directly translated to a success in the field. It is not surprising that electrolysis is now a major under hood problem. Another factor is the increasingly tighter environmental restrictions on flushing and disposal of automotive flush water.
How do we get rid of electrolysis? Since Type B electrolysis is a chemical problem as mentioned above, the answer to ridding ourselves of this problem will be to neutralize the acid. In addition we need to remove the spent antifreeze, remove any metal particles in the deep reaches of the engine block, and "scrub" the internal surfaces of the block. Since large volumes of water and pressure are not environmentally feasible, the next best option would be to enlist the aid of modern chemistry. A chemical flush. I call it 'flushing with a purpose'. By exposing the inner surfaces of the engine lock to the effects of the chemical action, the deep reaches of the engine block can be cleaned. This cleaning may require extended time or repeated application dependent on the severity of the problem. Once cleaned, fresh coolant and a suppressing additive is added to the cooling system, along with a sacrificial magnesium anode pressure cap. The anode takes advantage of the fact that electrolysis will choose the metal to attack in a preferential order. Magnesium outranks aluminum on the 'Galvanic Series' list, thus giving desired protection to aluminum components.
Successful treatment of Type B electrolysis involves:
1) Chemical flushing to disturb the sediment bed in the engine block
2) Specialized coolant additive that enables new metal to "plate up"
3) Sacrificial magnesium anode that gives up surface electrons
4) Replacing Aluminum Heat Exchangers with ones made from Copper/Brass
-excerpts from Voltage Drop Solutions Automotive Electrolysis Solutions for Ford Vehicles copyright 2013 used by permission :ihih: