Had occasion to purchase a new radiator today from manufacturer here in West Country who gave me a leaflet on this subject which I must confess I had never heard of as a cause for failing radiators. My scanner is on the blink so cannot reproduce the whole A4 sheet which details the simple test procedure for checking the coolant for an electrical charge but basically with a voltmeter on the range 0 -12v. with sensitivity of at least one-tenth of a volt with one test lead to battery ground and the other in the coolant (not touching any metal or the filler neck) Any voltage reading will indicate the presence of current through the coolant. A reading below 0.05volts is acceptable.
Heres the first paragraph which covers the problem.
Electrolysis is a highly destructive reaction casused by the passage of electrical current through coolant which destroys its corrosion prevention properties. A menace that attacks radiators and heaters and can destroy an entire engine within 12,000miles. Electrolysis occurs when electrical current flows through engine coolant in search of ground. It is most commonly caused when an electrical component or accessory somewhere in the vehicle loses ground usually from a broken or loose wire. When electrical devices lose their normal electrical path to the chassis or battery ground the current seeks out any other failure route. In most cases of radiator or heater failure loose or missing grounds can be traced to electrical cooling fans or relays. Another cause is bad ground wire from the engine to chassis.
We live & learn
Phil I
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Thanks Phil, that's a new one for me too.
I thought that it was a bit dubious, but a Google search for electrolysis and radiator came up with this site, and there's electrolysis in amongst all the other ways to wreck your radiator.
www.radiatorinfo.com/modine.html
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A very interesting topic, though the 12,000 miles seems a bit dubious to me! Electrolysis is usually to do with the breaking down of molecules in solution to produce gas and solids by the flow of an electrical current. For this you need (i) a very strong current flow (ii) a suitable electrolyte or conducting solution. This is also the method used for electroplating, where two electrodes are placed in a solution containing a metal salt and a high electrical current passed between the electrodes. One of the electrodes will slowly dissolve and a precipitate is formed on the other.
In the case of a car cooling system, given that most engine blocks are made of aluminium it is possible that a strong current passed through the coolant water could result in aluminium hydroxide production and the dissolving of aluminium, plus probably a bit of hydrogen and oxygen. As I am not a chemist, I am not familiar with the electrolysis of aluminium and antifreeze, but I do know that aluminium forms an oxide layer very easily which itself impends further attack.
For electrolysis to occur in the cooling system, it would be necessary for a high electrical current to be somehow injected into the cooling system. This could take the form of +12V on the thermostatic switch, or indeed any other similar sensors if they are wired incorrectly. I dont know what the electrical conductivity of antifreeze and water is, but I would think its very low. Also, consider the fact that many rubber hoses are used between the block and radiator, providing suitable electrical isolation in most cases.
The only path for a high current to leak into the cooling system as far as I can see would be the radiator switch. Perhaps its worth checking if the switch has a positive 12V section inside the coolant water?
Simon
SVPworld
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Electrolytic corrosion where two disimilar metals are in contact and then get wet (ie salt water from the road or from the contects of the radiator) is as old as the metal fabrication technique itself.
The radiator may be especially at risk but how many older 'classic' cars have well known rust problems due to the contact of disimilar metals...aluminium/steel.
In fact steel ships use this effect by bolting on blocks of zinc which acts as a sacrificial anode and literally rusts away leaving the steel hull untouched.
regards
Ian L.
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