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Old 09-03-2001, 07:52 AM
engatwork's Avatar
Join Date: May 2000
Location: Soperton, Ga. USA
Posts: 11,235
A way to check coolant contamination

Anybody ever hear of testing coolant this way.

If the coolant's age or condition can't be easily determined, there is a quick check for coolant contamination using a Digital Volt-Ohm Meter (DVOM). Attach the positive DVOM lead to the radiator, then dip the negative lead into the coolant at the filler neck.

A voltage reading of 0.2 volts or less is very good. A reading of 0.5 volts should be considered borderline and anything over 0.7 volts is unacceptable. If the coolant fails this test, the cooling system should be thoroughly flushed and cleaned. Remove any engine temperature sensors and inspect them for contamination or other damage. Repair as necessary.

From the site.
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Old 09-03-2001, 10:13 AM
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Join Date: Jul 2001
Location: SoCal
Posts: 1,303
This doesn't make sense as stated at the site. Presumably there is an error (eg Ohms instead of Volts), or insufficient info is given (eg the ignition is on and coolant temp sensor active, creating a measureable emf source via the coolant - highly unlikely).

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Old 09-03-2001, 10:14 AM
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Yes, there is an electrolysis effect within the cooling system. I remember many years ago when the big rigs had HUGE brass radiators there were zinc plates inside as a sacrificial metal. You could put a voltmeter from engine to radiator and read a voltage. They then began using additives that would virtually remove this voltage.

If you don't see voltage when measuring as described, it may mean that there are additives present in the cooling system that are masking the electrolysis effect (laymen's explanation).

Some months back there was quite a discussion about antifreeze and additives for same. Someone, if my memory serves me correctly I believe it was Longston, works in the field and had a wealth of knowledge regarding the subject. Maybe he, or whoever it was, could comment.

Have a great day,
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Old 09-03-2001, 10:34 AM
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Join Date: Aug 1999
Location: Florida / N.H.
Posts: 8,768
Well, it works.
Not sure how yet, but I just got .1 volt.
If you have a plastic tank, as Jim has, go to bat ground with the positive.
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Old 09-03-2001, 01:09 PM
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I would expect that putting the other lead in the radiator fins would be more meaningful.

Have a great day,
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Old 09-03-2001, 02:24 PM
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Join Date: Aug 1999
Location: Florida / N.H.
Posts: 8,768
[QUOTE]Originally posted by LarryBible
[B]I would expect that putting the other lead in the radiator fins would be more meaningful.

Why ???
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