Antifreeze Voltage Measurements

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I read somewhere along the line that electrolysis at a low level occurs in the cooling system. With a high impedance voltmeter, connect black to ground and put the red tip into the coolant closest to block or radiator you can, although it does seems to work with the overflow tank. I read different limits, couple of postings say .2V is max and one said .3V.
Tests should be done with engine running and accessories on too just in case there is excessive current running through the metal of the cooling system. If the voltage goes down with the motor off, then you have a grounding problem.

I ran tests on 4 cars (highest V noted, 1-2 factory fill, 3 not sure)
1. 4 years old, ford 5.4 (yellow) - 60Kmi
2. 6 years old, ford 5.4 (green) - 30Kmi
3. 7 years old, gm dexcool - 85Kmi
4. 40 years old, ford 289, glycol, last flushed 10+ yrs ago
with only 8K mi on antifreeze.

Results (neg voltage)
1. .095
2. .080
3. .120
4. .270
Did just a radiator flush on #4, got .120V. Put in Autozone green glycol.

Guess it seems to make sense, the lower the voltage, less problems there will be. However, I don't know if there is a correlation to ph levels, suspect there is but can't find any ph paper around here.

Comments ?
Thanks
 
There should be a decent voltage developing between dissimilar metals like an aluminium rad and the block. If there isn't, you'll have corrosion.

If you use the voltmeter tip as one electrode, the voltage will depend on what the tip is coated with.
 
This method is old school and works very well. The new methods are keeping the additives at the right level with test strips and replenishing additives. Both methods or either method is a good idea to perform on engines (like the diesel engine) that are prone to electrolosis erosion.

Regular Antifreeze (ACI) every two years will accomplish the same results. Some antifreeze filters have additives that slowly add chemicals during the filtering event. And you can add a bottle of a quality antifreeze additive for electrolisis at the 1 year mark as well.
 
Here is what I posted a few months back...got it out of a Handyman magazine...


Check your coolant conductivity with a multimeter.
1. Start with cold engine
2. remove radiator cap
3. start motor
4. Set voltmeter to 'DC' (20 volts or less)
5. after reaching operating temp, insert positive (+) probe into coolant.
6. Rev engine to approx 2k and place probe onto negative (-) side of battery.
7. If the meter reads less than .4 volts your coolant is good.
8. readings above .4 volts the electrolisis additives are exhausted.
 
I did a voltage measurement on my mid 80s honda crx, and got very low voltages, ranging up to 0.03 V. However, I also had some 6-8 ph strips lying around, and trying to be thorough, I checked, the pH: 6.4! This coolant was 7 years old (bad me) and looked disgusting, but the voltage measurement was low, ie good.

I think the voltage measurement tells you if you're damaging your car by electrolysis, while the pH tells you something else? corrosion? I also feel like the voltage depends on which metals are used in the cooling system (Al heads, steel cylinders, heating cores...)

Needless to say, I flushed and refilled.
 
First of all, make sure the coolant is fresh.

Second, the common thing I have seen for this is advice to ground the heater core.

Third, when seemingly good heater cores serially failed on 89 to 97 Thunderbirds, the only cure seemed to be to trash the aluminum heater core and install a brass one.
 
That be true, but after replacing several heater cores on the same car and then installing an aftermarket heater core made of brass and never seeing the problem again sort of speaks for itself.

And this was not just with one car, but with several. Surprisingly, the Ford rep approved the repair since there was a long string of parts warranty tickets. Actually, now that I think about it, he's the one that (unofficially) told us to get an aftermarket brass heater core on one of them.
 
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