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nissan
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Discussion Starter · #1 ·
Hey Guys,

So the pootrol ate a all aluminium radiator in three years.
diagnosis was stray current.
trying to find the source, I had all sorts of strange things going on with it last week and advice was get a analogue mulitmeter, and flush the system so you have water only in there.

OK, thats done.

So I went to it this morning, bearing in mind I filled and drove and drained the cooling system about 10 times at least last week with tap water to get it as clean as I could, and it is clean water in there now and I havnt driven it since then.
went to it and with everything off including ignition, it was reading 0.5 V
**** I thought to myself...
so I started unplugging things from the battery 1 by 1 until there was nothing left.
still 0.5V (depending how far you dip the probe into the coolant)

So I disconnected the USI-160 battery controller, no change, and started disconnecting things from both back batteries until they were isolated completely, IE no earth or power connected to them. Still no change.

Then I thought, ahhhh of course, the laminova intercooler has coolant mix in it, that must be storing a current blah blah, checked that and it had -ve voltage of about 0.2V
**** I thought, so I have no drained that and flushed it with water and then blown the lines dry so there is nothing in it, to eliminate variables.

Feeling chuffed that I had got it sorted and there would be no stray current now as all 3 batteries do not have their +ve terminal connected and only the cranking battery has its earth on, I check again.
0.5V STILL!

So I am stumped.

I ran some water into a bucket and tested that, 0.2V with both probes in the water. :shock:


No I am a little confused so I have supplied photos...
but basically the digital multimeter set on 2V (cause on 200mV it maxes out) reads 0.5V
the analogue one read higher earlier (5) but as in the photo is reading around 2.4 and as per the chart it says multiply by .01 (2.4*.01 = 0.024) photo doesnt show it, but yes it is in 0.1V setting...

SOOOO, is the digital or the analogue gauge right?

photos for reference:


The test piece:





the reading on the digital meter as shown in the arrangement above




and the analogue reading (pulled probs from digital and plugged to analogue)



reference table







Reading in the bucket (I know the analogue one is a bit hard to read cause its off centre, but its ~0.2) so 0.2 * 0.01 = .002




Why is the digital and analogue so different?!




And more to the point, why does my water have a voltage?!

the tap water and the water in my coolant....

Just for reference, on 20v setting on the digital gauge it reads 12.01V on the battery and 0.5 something in the coolant, so that scale seems to be correct...

blew the ass out of the analogue one by sticking it on the battery in the wrong setting...oops, might be taking that back for a swap over :p

any and all help appreciated guys!



Cheers, Andy
 

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just a good guy.
2009 gu ute
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do you have an earth going from rad to body. try that it worked on my 200sx when I was losing rads to oxidization.
 

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Y2KGUII ZD Wgn
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do you have an earth going from rad to body. try that it worked on my 200sx when I was losing rads to oxidization.
The subject of bonding has come up before, another thread a few months ago, there is no overall agreement on what should be done, some steadfastly say just keep the radiator fully isolated but that is not easy when the medium is water based and carries the current. I'm definitely no expert in this field but I went through a huge exercise on my 5.5m Ally boat with bonding after I found stray current I could not locate causing issues, so personally I think bonding is what I would be looking at seriously, I know it's not exactly the same but still pertinent.

http://electricalnotes.wordpress.com/2012/09/07/difference-between-bonding-grounding-and-earthing/
 

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Premium Member
nissan
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Discussion Starter · #5 ·
Thanks Bobby I will look. I did post in a couple of places.
I do not intend on earthing the rad tbh.
I always used demin water with my coolant but was told to use tap water to do the stray current testing.
 

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nissan
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every shop who makes their own radiators has their own opinion
same as if u google it and u just run round in circles

in the end the radiator shops don't want to warrant your radiator so they don't really give any advice
on fixing it so they are not liable

ive had people fit a million earths and it still didn't fix problem
 

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nissan
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i was told it was get into the pores of the metal and there was some additive that will nuetralise it so you can start fresh 3 yrs isnt too bad ive heard of them going in 3 months if all else fails possibly a sacrificial anode
 

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nissan
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Discussion Starter · #8 ·
3 years is OK. But it's not good enough. Can't go anywhere without a radiator and you can't exactly carry a spare and it's not something you can really keep an eye on.

What is it you are saying gets into the pores of the metal?

Cheers, Andy
 

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nissan
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Discussion Starter · #10 ·
I was going to do that.
But I have that issue with the water having voltage with nothing connected.
 

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nissan
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Just saw yr first pic
U might be measuring it wrong
Put the black lead from multimeter to battery ground
Put the red lead in radiator filler hole but the end of red lead must not touch metal radiator
It must only touch the water
That's how I test them in conversions

Not sure how far red lead has dropped in the filler hole in that pic so I thought I would ask

More earths don't usually help
If u had a bad earth many other things would fail in the car
 

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nissan
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Discussion Starter · #13 ·
Hey mate, I just dummied that up like that for the photo, but Yeh it wasn't touching as it was just floating in the end tank.

Cheers, Andy
 

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I saw somewhere else on the forum a post about waterless coolant. Don.t know much about the stuff but I wonder if this fluid can electrically isolate the radiator and not act as an electrolite to cause this corrosion.
 

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nissan
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Andy they analogue meter will be more of a true reading than digital due to how the internals of meter work, the voltage you are reading in bucket would be inaccuracy of meter, pics aren't working for me to see what you have done

Lets look at the technical properties

1. if you have a stray voltage generated by the car electrical system you will measure it from any part of the motor to -ve of Battery not just in the coolant, is this happening? I would guess no, measure it. earthing will negate this issue

2. dissimilar metals and a acidic liquid generate a voltage, this is what a battery is, coolant with 2 different metals in it will generate a voltage, maybe a sender mounted in radiator to create this.

3. is coolant compatible with the alloy used to make radiator, alloys are all different hence why some GM engines don't like particular coolants, sacrificial anode will help vaguely remember some early Falcons(may have been something else) use to have this to reduce corrosion issues

Hope you get it sorted, is corrosion an issue with factory/Nissan radiators or after market replacement?

Alternately fit a copper one:)
 

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nissan
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I saw somewhere else on the forum a post about waterless coolant. Don.t know much about the stuff but I wonder if this fluid can electrically isolate the radiator and not act as an electrolite to cause this corrosion.

i saw them use it on wheeler dealers its pretty expensive but when the engines at operating temps you can open the radiator cap because there is not water to make steam or pressurize
 

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Andy,
The difference in the readings is because the digital meter has a much higher internal resistance. With the reading in the bucket? Tap water is not pure, nor is rain water after is collected from a roof. This contaminates the water. Pure water is an insulator. It is only the contaminants that make it conduct electricity.
 
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