For a long time I thought I was the only one with this problem. Perhaps it’s because I never leave any of my cars alone for very long. It’s probably the price I pay for constantly changing stuff. This was a few years ago and we had just installed a LS engine into my orange ’66 Chevelle. We called the engine Lester Scruggs because its’ initials were LS. Along with the engine, we added a Be Cool aluminum radiator because it seems appropriate that an LS engine should have an aluminum radiator. Lester was an iron block 6.0L truck engine with factory L99 aluminum heads that had been ported. It ran its first few passes at around 11.70 at 122 mph, so it had potential. That’s when the problems started.
After only about two weeks and perhaps 1,000 road miles on a trip to Phoenix, the aluminum radiator started to leak out of the middle of the aluminum core. We weren’t sure what the problem was, but Be Cool sent us another radiator but this time, just for drill, we checked the coolant for electrolysis. The procedure is to place one probe of a digital voltmeter on the radiator cap boss for a ground and immerse the positive probe in the coolant, not touching the metal part of the radiator. Just like any storage battery, if you place two (or more) dissimilar metals in an acid, this will generate a voltage. The industry accepted maximum voltage is 300 millivolts (mv) or 0.30-volt. When I first tested my radiator, the reading was 400 millivolts with cold coolant. When the engine reached 180 degrees F, the voltage spiked to nearly 850 mv. This was a bit of a shock, because this much voltage is an indication of current flow and a transfer of electrons. This excessive voltage will literally destroy the thin aluminum tube in a radiator in a matter of weeks. But at least this pointed us in the right direction.
I won’t subject you to the entire, long drawn-out story but we never really fixed the problem. I worked with Jay Ross, who runs Applied Chemical Specialties and makes a high quality anti-corrosion additive called No-Rosion (No-Rosion.com). I learned far more than I wanted to about electrolysis as a result of diving deep down the electrolysis rabbit hole. Basically, there are two types of electrolysis: chemical and electrical. Often, electrical components like a charging system can ground through coolant causing electrolysis. The chemical part mostly has to do with the coolant becoming very acidic. In my case, the cause was neither of these two concepts. We could remove the charging system completely and at 180 degrees of engine temperature we still had 800+mv and even with pH-balanced coolant and very pure water, we still had a problem.
Jay mentioned that sometimes similar metals can actually transfer electrons and if those metal alloys are immersed in a common solution of coolant, one will feed electrons to the other with the transfer occurring through the coolant. Until recently, there was not much we could do about it until we eliminated the alloy that needed the electrons! Our fix for this problem was to replace the aluminum radiator with a brass-copper unit. As soon as I did that, the coolant voltage dropped substantially.How’s that for weird? What’s worse, I just now checked the coolant after a couple of years of running and it’s now up to 350 mv with the engine cold. Not good but at least this high voltage isn’t killing an aluminum radiator.
Just last week, a friend called with a similar electrolysis problem. He has a late model Chrysler Gen IV 6.4L hemi in a ’69 Chevy pickup and had heard about my testing and called to see if I had any recommendations. I told him to drain the coolant and flush the system and then add the No-Rosion anti-corrosion additive that I use in all my cars. His problem was a coolant system voltage of more than 500 mv. I told him he should begin by checking for excessive charging system voltage but if he found no problems, I suggested trying a brass-copper radiator to see if that reduced the problem.
I also contacted Jay again to see if anything had changed in the last couple of years and he told me he is working on a new anti-corrosion additive that addresses the electronegativity problem. It is based on chemistry fundamentals that deal with ions in solution and that’s as much as I know about it right now. While admittedly, this issue is a rare occurrence, I think that there are probably others out there with similar problems. Hopefully there will be more answers forthcoming.