Grey stuff in rad opinion

[syrinxstar]

[quote author=Rich link=board=2;threadid=14475;start=msg138097#msg138097 date=1081834633]
the fundamentals of electricity are getting thoroughly mangled in this thread. [/quote]

You're right again Rich. Apparently you believe that voltage potential is some magical quantity that exists independent of other electrical phenomena. ??? ??? ???

Voltage potential is a function of current and resistance. End of story - don't bother trying to explain your way out that. When you place one lead of a voltmeter on the battery ground and one lead in the coolant you're getting a reading that is a function of the small amount of current flowing between the leads and the collective resistance in the path that the current flows. So is the voltmeter giving a reading of conductivity, resistivity, or amperage? No, it's giving a reading of volts but that reading is dependent on the resistance of the system. It's all related Rich!

I guess the simplest way to end this is to look at your own actions. You've measured the potential between the coolant the battery ground. Why would you do this? Obviously you're trying to assess the state of the coolant. What could the coolant possibly add to a voltage measurement? What would you conclude if you went back a week later and found a different reading? Does coolant spontaneously generate voltage? current?? Nope, the coolant serves as a resistor in the circuit and that resistance (conductance) presumably changes over time, and this all possibly ties in to how "good" your coolant still is.

Plain and simple and, yes, a fundamental of electricity and circuit analysis.

 

[cruiserdan]

Nice piece Simon.

It should be noted that the "control" vehicles are both early production 93's, not a very representitive sample I fear. :-\ It would be nice to find a 95-up vehicle in the crowd. Photoman is out becaues he has played with radiators too much on his to be of statistical use.

 

[Rich]

Mike,

A number of members have posted their voltages readings measured between the coolant and ground. If you believe that this is measuring the conductivty of the coolant, please tell me what the conductance of the coolant is for each report. umhos-cm would be an appropriate unit of measure for stating the conductivy of a fluid.

Of course this is a rhetorical request, because you can not possibly ascertain the conductivy of the coolant based on only knowing the voltage between the coolant and ground.

I fully understand the relationship of voltage, current, and resistance, and how to measure each. If you also understand that relationship then you will agree measuring only voltage does not allow one to ascertain conductance without also knowing the current that is flowing through the same material.

I measured the voltage myself to ascertain if there is a possiblity of a stray current problem, which, if it had existed, would be a problem with the electrical wiring in the truck. I had no intent nor expectation that I was assessing the state of the coolant.

 

[syrinxstar]

[quote author=Rich link=board=2;threadid=14475;start=msg138355#msg138355 date=1081882952]If you also understand that relationship then you will agree measuring only voltage does not allow one to ascertain conductance without also knowing the current that is flowing through the same material. [/quote]

I agree and I've never stated that a voltmeter will display conductance; simply that when you measure voltage, it will be dependent on the resistance and current between the leads. If you remember, you wrote that the coolant-ground measurement does not measure the conductivity of the coolant but, effectively, it does and it's a prime factor in that voltage reading. The coolant-ground resistance will presumably change over time in response to a degrading coolant. The current will change based on the current voltage level across the battery terminals. Accounting for (normalizing) the battery voltage, each time you make the coolant-ground voltage measurement you are effectively making a resistance (conductance) measurement because the normalized current will drop out in the ratio of final voltage over initial voltage. So will I get an actual conductance reading, no. But over time I'll get a percentage change in that reading that I can presumably attribute to the change in coolant resistance.

Rich, you've been taking a very literal view of the situation. I've challenged you to "think outside the box" and understand how simple measurements can be used to gain insight on variables that are more difficult to determine, at least with the standard shade tree mechanic's tool chest. Often times it's not possible or practical to make direct measurements of variables - this is where inference and deduction come in to play. 8)

 

[IdahoDoug]

If I'm interpreting this right, I believe what Rich is saying (and I agree) is that these voltage measurements on various vehicles are essentially meaningless in terms of measuring coolant conductivity. The reason they are meaningless is that to assess loss of current due to high or low conductivity you'd have to know the starting current for each vehicle so you'd in turn know how well or poorly the current was conducted.

Said another way, conductivity simply expresses what % of the current gets through the circuit. In this discussion the coolant is part of the circuit in question. So knowing only the reading after the current has passed through the coolant tells you nothing about the coolant's conductivity. It only tells you that whatever the current started as (Y - unknown quantity), it was measured as X (X being our various readings posted). To measure conductivity you'd need the Y. As far as I know, the size and shape of the water jacket and its many contacts with various vehicle components, would make establishing Y near impossible. Kinda scary to think of all the places the water jacket could pick up stray current, actually - yeesh!

Even knowing conductivity of the coolant may not be useful as I'm not aware of any correlelation between coolant's conductivity, and its state of wear or ability to protect the engine. There may be one, it's just that I don't know of it.

HTH,

DougM

 

[syrinxstar]

[quote author=IdahoDoug link=board=2;threadid=14475;start=msg138412#msg138412 date=1081887404]
you'd have to know the starting current for each vehicle so you'd in turn know how well or poorly the current was conducted.[/quote]

Doug, you'd find this by measuring the voltage across the battery terminals. Each time you make the measurement, you scale it by whatever the voltage happened to be at the moment across the battery (eg 12-18V). You'd want to make sure the same "load" is on the battery (i.e. no additional accessories, stereo off, etc.) In this way, the current gets normalized and you can essentially cancel it out when you make the measurement next time, taking the ratio of initial voltage and final voltage.

You're right on the bottom line - I have no idea if taking this measurement is even meaningful. I'm not intending to be argumentative either - just merely pointing out that you can get a reasonable estimate of the change in coolant conductivity over time by just using the coolant-ground measurement.

 

[RavenTai]

[quote author=syrinxstar link=board=2;threadid=14475;start=msg138258#msg138258 date=1081871635]
What could the coolant possibly add to a voltage measurement? What would you conclude if you went back a week later and found a different reading? Does coolant spontaneously generate voltage? current?? [/quote]

coolant can generate a voltage if there is corrosion (especially galvanic corrosion) or other chemical reactions taking place, I thought this is why we were taking measurements? with the engine off I get no voltage potential between the block and neg post of the battery, so I do not think the voltage we see in the coolant is stray voltage from another circuit but generated right there in the cooling system

http://www.reliability.com/articles/guest_article03.htm

 

[Rich]

[quote author=syrinxstar link=board=2;threadid=14475;start=msg138395#msg138395 date=1081886065]
I agree and I've never stated that a voltmeter will display conductance; simply that when you measure voltage, it will be dependent on the resistance and current between the leads.
...
If you remember, you wrote that the coolant-ground measurement does not measure the conductivity of the coolant but, effectively, it does and it's a prime factor in that voltage reading....
[/quote]

Mike,

In a previous post you directly stated, while quoting me, that measuring the voltage between coolant and ground is measuring the resistance of the coolant.

Immediately above you again restate that measuring the voltage between coolant and ground effectively measures the conductivity of the coolant. Both of these statements are false.

You do not know how much current is flowing through the coolant. You do not know what the path of the current flow is. If the measurement varies over time, you have now way of knowing, based on that measurement of voltage between coolant and ground, how the change is being influeneced by factors external to the coolant. Battery voltage is only one of many variables that can cause the voltage measurement to vary over time that are independent of the coolant's conductivity.

If you choose to directly measure the resistance from coolant to ground you would still have no way of knowing what the contribution to resistence is attributable to the hoses, to the engine head (which is grounded to body) and the engine block (which is grounded directly to battery).

My whole point is if you wish to know whether or not you may have a stray voltage problem with your cooling system that is or could be causing corrosion problems, then measuring the voltage from coolant to ground is a meaningful measurement. If you wish to measure to conductance of the coolant in order to know something (meaningful or not) about the coolant, then you will need to do something very different than measuring the voltage potential between the coolant and ground.

 

[syrinxstar]

Rich -

I've used coolant resistance and conductance interchangeably. They are related, get over it.

Current will take the path of least resistance when I create the coolant-ground circuit - it's not going to travel through every atom of the engine in my measurement. It would be fair to exclude significant variability imparted by hoses, blocks, and heads. Again, the current doesn't have to necessarily flow through them but it does have to flow through the coolant and given the poor conductivity of fluids compared to the rest of the metal in the coolant-ground circuit, it will likely be the dominant resistance. Obviously there are a ton of factors that can affect the measurement, temperature being a prime example. It's not unreasonable to believe that measurements taken on a cold engine, and adjusted for the state of the power supply (battery), that measurements of voltage over time will be proportional to the conductivity of the coolant. I've not said that this is a particularly sensitive measure of conductivity and in fact I'd believe that it's a rather gross measure. Depending on how much a change is needed to detect would dictate whether the method is acceptable. You've not offered anything particularly enlightening to dissuade me of this and my guess is this feeling is reciprocated.

 

[cruiserdan]

Genlemen, gentlemen

Let's not pee all over hot radiators, it smells bad

 

[semlin]

Doug, thanks for your comments. I did warn you about the java.

I agree with you that the 80 is well engineered. The question is, for what applications and what stresses? I suspect engineering them for north america is an afterthought. This happens to be the only place in the world these trucks with gas motors would frequently be run flat out at high revs on sustained steep grades , and the onyl place in the world where people driving them would be expecting performance comparable to a V8 on hill climbs. There are a few places in Europe with the steeps maybe but they mostly run the diesels there. Otherwise the rest of the road does not have the roads for it or, in the case of Oz, the hills.

Are you really that sure it is healthy for these motors to run at over 3,000 rpm geared down under a heavy load on a sustained basis? Are they not running significantrly hotter when they do this than at 2300 rpm on a flat in overdrive?

 

[turbocruiser]

[quote author=semlin link=board=2;threadid=14475;start=msg138678#msg138678 date=1081907456]
Doug, thanks for your comments. I did warn you about the java.

I agree with you that the 80 is well engineered. The question is, for what applications and what stresses? I suspect engineering them for north america is an afterthought. This happens to be the only place in the world these trucks with gas motors would frequently be run flat out at high revs on sustained steep grades , and the onyl place in the world where people driving them would be expecting performance comparable to a V8 on hill climbs.
[/quote]

Trust me, these vehicles are abused throughout the wide world in much much much worse ways than we would imagine. The Middle East in particular is prime example, over there the people run these things flat out through sand, through terrific temps, through everything. They frequently install turbos exactly like the one I operate with no problem. They run them as hard and as long as possible. Even when I was in Central America, all the 80's that were there were abused and abused over and over again with AC on full, with all sorts of stuff loaded up on the roof, with all sorts of stuff towed, on and on and on. I think we should simply strip the hypothesis that NA spec'd cruisers cannot handle the super seriously demanding NA driver or driving conditions. I also think we should, in an effort to adhere to scientific method, confirm or at least allow either the voltage or the ph readings to, as I suggested, help as another analysis for when the coolant may need replacement. Lastly, I think we should stop screwing around with all this thought (as fun as it is), find out what the cost to send the samples for analysis is, and then split that cost up among those that are interested in analyzing it. JMHO.

 

[turbocruiser]

Sorry, wanted to add that, when I wrote that we should strip the thought that 80's are not adequately spec'd, I only intended to say this from a scientific or statistical perspective. Not intending to imply that it was a flawed or faulty theory, just that it was one of many possible theories and many possible variables, and probably a variable appropriate to eliminate while we focus on others. Also, was not intending to say that we were collectively screwing around in wasted effort, far from it, this is one of the most productive and thought provoking screwing around sessions I can recall! Anyway, I'm in the habit of reviewing my posts a few rum and cokes later and making sure it is not worded wrong to anyone.

 

[cruiserdan]

Rum will rust yer Newton valve I suggest Keystone Light.

 

[turbocruiser]

[quote author=cruiserdan link=board=2;threadid=14475;start=msg138722#msg138722 date=1081911238]


Rum will rust yer Newton valve I suggest Keystone Light.
[/quote]

Well, Dan, ahh, I only use OEM, (thanks by the way for making that so possible) and, I always keep a spare available so let the Newton Valves Rip Baaabbby!!! By the way, if you are really consuming that crap Keystone Light, let me seriously find a way to send you and Beowulf some of that terrific Boddingtons that you know is so much better for the old Newton Valve! I'm still searching for the 24 pack though!!!

 

[cruiserdan]

Hmmm,

I'm a tad surprised that a Colorado lad would bad-mouth Coors... (even if it is "private labeled")

 

[e9999]

how weird, page 3 was going on full blown on electrical stuff that I ended up skipping when some of what I read did not exactly jibe with the electrical circuit basics I remember, and then page 4 seems like a different world. So abruptly...
Surrealistic!

anyway, want to add one thing to the melee and I don't even want to check first what that contradicts of not.

This is how I picture the situation.
There are 2 voltage levels: 12V (OK not exactly 12 but will do) and 0V. The 2 battery electrodes.
Picture a multitude of little wires between the 2, each one being a separate circuit and function, some rea, some carrying stray currents, one of them having the coolant as its conductor. What you are doing is measuring the voltage level somewhere along the "coolant" wire. Depending on the location you will get a different reading because the "resistance" (read distance) to the closest ground varies. Forget current through the voltmeter if it's any good.
Nothing different than measuring the electric potential at various location in a liquid layer with 2 electrodes in it. You can do a whole map of equipotential surfaces that way. Anyway, clearly the reading will be a function of the resistivity of the liquid. Measure the voltage at a given location (say rad cap) and if the rest of the circuits do not change (!) but the voltage changes with time, bingo that's your coolant resistivity changing.
I'll check mine for fun.

Thazzall for me...
E

 

[Beowulf]

>> let me seriously find a way to send you and Beowulf some of that terrific Boddingtons ... <<

I was dozing off but I THINK someone mentioned my name... and I KNOW they mentioned my beer of choice.

Send away my friend, send away.

-B-

 

[e9999]

eh, I like the bit about gray sludge inside the inlet hose to the rad!
So, if I take the hose off and see no gray sludge, does that mean I probably don't have sludge in the rad then?
yea for that test!
E

 

[Rich]

Mike,

Your argument continues to be incorrect. Electricity does not follow the path of least resistance. For example, in a circuit with two resistors in parallel, say one with a resistance of 5 ohms, and another with a resistance of 100K ohms, with a voltage potential existing across both, current will flow through each, in direct proportion to the resistance of each. It works exactly the same in your engine. The physics are no different. If your coolant is at a different potential than ground then current will be flowing through the coolant, hoses, block, and head, grounding connectors, and body in proportion to the resistance of each.

Even things as simple as the hoses do not remain constant. After 40K miles my upper radiator feed hose was internally coated on the inside with a thin brown "mineral" deposit. Likewise the metal upper feed pipe was internally coated with grey sludge.

I wouldn't be at all suprised if the amount of moisture, dirt, and oil on the engine, wiring connectors, and engine mounted electrically operated devices, and also the age and condition of the same has a significant impact on the typically low voltage potentials being measured from radiator coolant to ground.

With respect to the coolant, the ethelyne glycol itself is what predominately determines the conductance of the coolant. So even if you were to invest in the equipment necesary to measure the conductance of the coolant, you would not gain any insight into the remaining life of the coolant, without taking further measures necessary to minimize the impact that glycol has on the measurement.