Some time ago, Duke W mentioned a tip he had beem given to test coolant. It was to put a voltmeter positive probe in the coolant and ground the negative probe. A reading of less than 250 mA was OK, more than 500 mA bad. I tried to do this several times but get a result I do not understand. The meter will not stabilize, but begins a slow countdown, 1 mA at a time. The initial reading when I start over is never the same, but where ever it starts, the countdown begins. Any thoughts or suggestions?
-
-
Re: Measuring Coolant Voltage
Hiya Scott -
Sorry, I'm not familiar with this technique. But if Duke said to use a voltmeter, then you should be seeing volts (V), not milliamps (mA). So I'm thinking that you might have your multi-meter set on the wrong scale?
Pete -
Re: Measuring Coolant Voltage
Gordon, Thanks. Duke's tip said millivolts and that's thats where I had the meter set; I just typed it wrong. I actually already tried reading milliamps before I originally posted just in case the tip had a typo.Comment
-
Re: Measuring Coolant Voltage
With a digital multimeter set on the voltage scale (set on a low scale to read up to 1 volt if it is not self ranging) remove the fill cap and place the positive probe in the coolant and the negative probe on a good ground, like the battery negative post. I've only done this test on conventional IAT coolant. I'm not sure if this "test" will yield the same readings on OAT (like Dexcool) or HOAT (like Zerex G-05 that I now recommend).
Try it again and tell us what you get. Also, what kind of coolant is installed and how old is it?
DukeComment
-
Re: Measuring Coolant Voltage
Duke, Coolant is good 'ol conventional Prestone. It is two years old which is why I looked up your old post and thought I'd check it. I did exactly as you described above several times and got the result in the my original post. I even tried it with the battery cut-off switch on and off and also using the block for ground.Comment
-
Re: Measuring Coolant Voltage
Other than ensuring that your multimeter is on a scale to measure 0-1 VOLT, I can offer no advice. I haven't run that test in some time, but when I did, cooling systems in good condition with antifreeze that wasn't excessively aged measured about 250 millivolts - NOT milliamps.
If your antifreeze is only two years old, I would not be concerned with the readings, but suggest it's time for an antifreeze change, and this time use Zerex G-05.
DukeComment
-
A Better Result
Tried again last night with the same results; unable to get a stable reading. Switched the meter to volts instead of millivolts and after a minute or so it finally stabilized at .075 volts (75 mV). Without remocing the connections, I switched back to the mV setting and got the same results as before; an unstable reading slowly counting down. Switched back to volts again and the reading stabilized at .075V. I'm not electrically savvy enough to explain why, but at least that's how I got the "test" to work. FWIW, the coolant was at room temperature.Comment
-
Re: A Better Result
...could be something wrong with the meter. IIRC the one I used was self ranging. That's a low reading, which indicates very low electrolytic activity in the cooling system, but you might want to borrow another meter to verify the readings.
DukeComment
-
Re: A Better Result
Just tried a high buck Fluke meter. Same result as originally. Tried both V and mV settings. I think it never really stabilized with either meter, it just slowed dowm to the point where it looked like it in the larger V scale. It got very slow around 57 mV, same as it did with the Craftsman meter I have at home.Comment
Comment