Help! Voltage in heat exchanger and tank!

[golkhl]

Trying to chase down an electrical gremlin and need some help. When testing for electrolysis in my cooling system, i found that my afco heat exchanger and moroso aluminum coolant tank are electrically charged. Any ideas? Usually this is caused by a missing or bad ground. Only ground in the heat exchanger loop is the coolant pump, any other ideas on what might be causing this?

 

[golkhl]

Pic of heat exchanger voltage.

 

[golkhl]

Pic of heat exchanger coolant tank voltage.

 

[BruceH]

Trying to chase down an electrical gremlin and need some help. When testing for electrolysis in my cooling system, i found that my afco heat exchanger and moroso aluminum coolant tank are electrically charged. Any ideas? Usually this is caused by a missing or bad ground. Only ground in the heat exchanger loop is the coolant pump, any other ideas on what might be causing this?

You could ground them but the voltage seen is because of differences in the galvanic scale. I'm sure you are aware of galvanic corrosion, commonly referred to as electrolysis. Every metal has a different galvanic number and the differences cause electron flow which makes corrosion possible.

Aluminum and steel will always have electron flow between them due to galvanic differences. You could use a sacrificial anode to concentrate the electron flow to something else. You could also provide an insulating barrier between the tank and frame.

 

[golkhl]

Thank you for the info. Bruce. Ordered a couple of ground straps, was thinking i could ground the heat exchanger, radiator, and possibly the aluminum tank. Any other tips, tricks, advice would be much appreciated.

 

[BruceH]

Thank you for the info. Bruce. Ordered a couple of ground straps, was thinking i could ground the heat exchanger, radiator, and possibly the aluminum tank. Any other tips, tricks, advice would be much appreciated.

I think that a ground strap would accelerate electron flow and corrosion. The voltage being read is because of the path to ground through the multimeter. I thought I had pointed that out in my first response but after rereading it the thought isn't real clear on my part.

I'm on some meds right now and might not be thinking this through correctly but as I remember my USAF corrosion training unless the two dissimilar metals have a contact path corrosion can't take place. A ground strap completes the contact path and is not desired unless it's needed to dissipate static electricity.

What I'm saying is that imo you would be better off leaving it alone or insuring a positive separation between metals with a barrier like rtv, plastic washer, etc.

More than likely there isn't an issue as is imo.

Your best bet is to educate yourself on galvanic corrosion and make the decision you feel most comfortable with.

 

[golkhl]

Bruce: thank you again for the info., i am thinking that i have a bad ground somewhere, and the stray voltage is finding its way to the coolant system. Checked the ground wire on the coolant pump, checked the battery ground, could not find the engine ground wire? Heat exchanger is an afco(no fans) and is rubber mounted. Heat exchanger coolant tank is mounted to the fan shroud, with no metal to metal contact. I am really at a loss at this point.

 

[Pentalab]

You have the BLACK test lead plugged into the WRONG jack on your DVM ! It should be plugged into the COM jack...and not the DC 10 A max jack.

As is, you have the DVM switched to read 200 vdc. It should be on 20 vdc. Your readings are bogus.

 

[Candy10]

LMAO.

Its common. Bruce is spot-on as to why. If you want to add a bunch of grounds to everything, it won't hurt. But it likely won't help either.

If you are detecting corrosive resistance, adding grounds won't matter. I think Bruce pretty much summed this up, but let us know what you find,,,,,,, when you figure out how to use a DMM


EDIT: I mispoke (mistyped), adding grounds CAN speed up the process.

 

[hamish]

You have the BLACK test lead plugged into the WRONG jack on your DVM ! It should be plugged into the COM jack...and not the DC 10 A max jack.

As is, you have the DVM switched to read 200 vdc. It should be on 20 vdc. Your readings are bogus.

I am seeing what you see, OP, better get out the DVM manual.

 

[golkhl]

Thank you for the heads up on how to set up the dvm, but still seeing voltage in the coolant system.

 

[Candy10]

Lets start over.

WHY are you testing this?
WHAT is your gremlin?
Did you probe the coolant itself? (with ground probe to battery neg)
Is the reading you are getting a big deal, worth worrying over?

Ill answer the last one; maybe.

From a radiator shop; "Make sure the radiator/HE is never used as a ground." This will increase the corrosion process, so forget the ground strap to radiator idea.

Is your ignition ON, or the engine running?

 

[golkhl]

Had electrolysis in my engine coolant, while trouble shooting that problem i found that most of the coolant system had voltage.

Thought the gremlin was a bad ground, as a bad ground leads to stray current, which takes the path of least resistance often resulting in cooling system electrolysis.

Simple fix would be to add a radiator anode, but the petcock on my CSF radiator is M12x 1.25, and the anodes available online are 1/4".

Not trying to make a mountain out of a mole hill, but just want to make sure everything is in proper working order.

Thanks again.

 

[BruceH]

Thank you for the heads up on how to set up the dvm, but still seeing voltage in the coolant system.

Due to differences in the galvanic scale there will be electron flow when dissimilar metals come into contact with each other. The multimeter is making them come into contact with each other.

 

[Candy10]

Had electrolysis in my engine coolant, while trouble shooting that problem i found that most of the coolant system had voltage.

Thought the gremlin was a bad ground, as a bad ground leads to stray current, which takes the path of least resistance often resulting in cooling system electrolysis.

Simple fix would be to add a radiator anode, but the petcock on my CSF radiator is M12x 1.25, and the anodes available online are 1/4".

Not trying to make a mountain out of a mole hill, but just want to make sure everything is in proper working order.

Thanks again.

Its all good, man, just wanted to be sure your testing right. There will always be a reading, is what I'm getting at.
However, I don't know what the "acceptable" limit/range would be.
Bruce might know.


Now I see the chart^

 

[JeremyH]

Bruce is spot on. Your readings look pretty normal to me, or what any one could expect to see in other words. Another tip would be to use the best scale on your meter for what your testing, looks like you are set at the 200 volt dc setting for reading fractions of a volt. I would use that 20vdc setting. Edit I see pentelab already noticed it too.

We use zincs as anodes on the ship to protect aluminum and steel from corrosion.

 

[golkhl]

Trying to source an m12 x 1.25(csf radiator petcock threads), to 1/4" npt(zinc anode thread size) so that i can install an anode.

M12 x1.25 male to 1/4" npt female adapter is not a common size, if it exists at all.

 

[Candy10]

I went out and checked mine,, it was buggin me.
Engine coolant .20v (car off)
S/C coolant .34v (car off)
S/C coolant .05v (pump on, engine off)

I didnt think to go back an check the engine coolant with the key on.

Might test again with the car hot, because bored haha.