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Electrolysis & radiator coolant?

Has anyone ever heard of a problem where the car’s cooling system – for example the radiator – is degraded due to electrolyis, and this condition is somehow connected with the radiator fan? I heard someone say this on the radio the other day. I’ve never heard of this. Apparently to diagnose this condition, you are supposed to measure the voltage between the coolant in the radiator and the car’s ground, and if it is more than a certain number of millivolts, then electrolysis may be occuring in the cooling system.

First of all, how could the voltage reading be anything other than zero? I mean the coolant is in contact with the engine, so it must already be at ground potential. And I don’t see how the radiator fan is connected to this. Isn’t the radiator fan usually electrically insulated from the metal parts of the radiator?

And what can be done about it? I mean should the millivolt reading excede the voltage specifications?

Just curious. Anyone ever run into this problem and could offer an explanation?

Sure! If you take volt meter and put one probe into the coolant and the other to ground, and if a voltage is measured it means the coolant has broken down and cooling system has become a battery.

But that’s 70’s-80’s technology


Ok, so to fix it you replace the coolant? How is the technology different today? YOu mean the coolant is different, or the cooling systems are different?


If you read voltage from the cooling system, replace the coolant.


Do you believe you are encountering this problem?

Tester is right, but I have also seen this with radiators that came from the Philippines. When some people had issues with their plastic/aluminum radiators, they would order these copper/brass replacements.

The problem is that the state of the art of metallurgy in the Philippines had some inconsistencies and some of the alloys, when used with aluminum heads and blocks would turn any coolant, or water into an electrolyte. But the erosion was usually to the head as the aluminum is a more active metal.

I have never heard of a fan becoming involved though. The radiator core is aluminum and mounted between two plastic tanks. I don’t believe the core is grounded anywhere, so if a voltage was somehow induced into the core, it could only find its way to ground through the coolant. That could cause erosion of the core I suppose. I just don’t see how that would happen unless the coolant became acidic, which some of the OAT additives in some coolants will do, and the radiator core becomes one plate of a battery, the block becomes the other one.

@db4690 … Mostly I asked because I’m just curious about what I heard the other day on the radio. I’m trying to understand. It appears it caused a battery situation, created by unlike metals between the radiator and the engine and worsened by a conductive coolant. That makes sense. I think I possibly may have experienced this problem, as my early 90’s Corolla radiator sprang a leak a year or so ago, and I had to replace it. When I looked up the service bulletins on AllData, it mentioned that some radiator problems had occured on this car and the service bulletin said to measure the voltage between the coolant and presumably the car’s ground. I didn’t do it, because I had flushed the system, put in new coolant when I replaced the radiator, and since the old one lasted 20 years and the replacement was inexpensive and easy to replace, it didn’t seem that big of an issue to worry about.