voltage in radiator coolant

[AECS]

So here it the story.

I installed a new aluminum radiator and heater core yesterday, and all was well, then I checked the coolant to negative terminal to be sure I didn't have ground issues, and i got almost one full volt! Not good at all.

The weird thing is as the coolant cooled the voltage dropped, to .3 volts. I grounded the radiator to the frame where the battery and passenger headlight grounds to the body. Pulled and cleaned where the battery grounds to the frame, where the 24v negative buss grounds to the block, and where the block grounds to the cab. I am still getting .17 volts, but the coolant is now ambient temp, so I will have to see what happens tomorrow after I drive it a bit. This is driving me nuts!

I am using a Fluke 77 and a Craftsman meter, they zero when the leads are shorted. Also I read zero ohms verifying grounds.

I get zero volts checking coolant with battery's disconnected.

If I am at under .2 tomarow at operating temp I am going to let it ride as is, what say the experts?

 

[trukhead]

Perhaps the coolant is going acidic and the dissimilar metals of the coolant system are acting like a battery and creating a voltage. All the metal parts of the coolant system are directly connected to ground. Acidic solution (the coolant) and dissimilar metal will generate a current.

 

[AECS]

Thought about that...Wouldent I get voltage with out the batts hooked from coolant to ground?

 

[MarcusOReallyus]

Thought about that...Wouldent I get voltage with out the batts hooked from coolant to ground?

Yes.

So, your grounds are not what they should be. That much voltage is going to EAT your radiator, so you must solve this quickly. Even .2 volts will do a number on you. BTDT.


I suggest cleaning ALL your grounds thoroughly, and make sure you get into threads, too. (A bore brush of the appropriate "caliber" works well for this, chucked into a drill.)

Get them shiny bright! Then coat them with either dielectric grease or a conductive grease.

I'd also add a good ground between the radiator and the battery terminal, and another to your heater core, and to the block. Bring them all together to one common connection with your battery ground terminal. People with boats call this "bonding". I'm sure it will be a bonding time for you with your truck.

You are getting some voltage somewhere, and you need to kill it.


Also consider adding a zinc to your system. It's not a substitute for good grounding, but it's another layer of protection. You can find them to fit in place of your petcock (if your radiator has one), and I've seen some that are part of the radiator cap, and finally, there's one place in California that makes one to fit in your radiator hose. I have one, and it looks to be decent quality.

 

[doghead]

Did you use new coolant?

 

[doghead]

http://www.arrowheadradiator.com/Electrolysis Article.htm

Tons of reading if you google " voltage in coolant".

http://www.rondavisradiators.com/tech.htm

 

[renodogs]

Trukhead is correct. You have a very small amount of B+ being generated by the chemical reaction of the coolant and the radiator. This is better known as electrolysis. Use a GM radiator coolant (pale yellow) specifically made for aluminium radiators. Running the old school green anti-freeze works fine in older style radiators, not so much in the newer stuff. Can you get away with it? Yes, Will it hurt anything? in time, yes. Also, if you have rubber seals in new aluminium radiator, they will eventually go away from the methanol used in the green coolant. The methanol is the 'puppy killer' component in anti-freeze, and the GM stuff is formulated to avoid electrolysis that will always start using the green stuff. All late model aluminium blocks and heads for GM require the pale yellow coolant for this reason. The basic anti-freeze coolant can be made by mixing straight methanol and glycerine to produce the coolant. Essentially, it's the old German Afirka Korps mixture from WW2. Methanol eats away at rubber seals by dry rotting them. My buddy found this out the hard way with his BMW because didn't use the right anti-freeze in his car. oopsie.

Something of note* Ford requires an additive to their coolant for the early 7.3 diesel engines to avoid 'pinholes' developing in the block and water pumps from electrolysis. I have owned 7.3's for many years and always run the additive to avoid this problem. My kid was a service writer for Ford in their commercial division and saw this condition fairly often after an aged 7.3 diesel came in for maintenance. As was mentioned before, checking for a good ground in your system is mandatory. I've been fixing electronics for over 34 years and if there's one thing I have seen people neglect or don't understand, it's the concept of a good ground. You have to treat a ground wire just like you would the positive side. It's the other side of the battery positive post, and without it, anything in between acts as a 'load'! This is the reason why alternators mysteriously go up in smoke, batteries overheat, and windings in starters short. Ground is ground, the world around.

That said, on military vehicles there are two things that commonly are at fault: corrosion and the careless Private Numnutz who gets a little too vigorous with that OD green paintbrush. Clean all contacts with a decent wire brush, coat the area with any auto parts store battery connection spray (the red stuff)- but don't spray that stuff into or onto the alternator regulator area. Running a ground from the frame of the radiator, to the alternator, to the battery is a way to check if that is the problem, but it really isn't necessary. Nonetheless, if you still have the B+, get rid of your coolant and switch to GM coolant. You could also try the additive that Ford recommends for their 7.3 diesels, but I think that's something I would do as regular maintenance to avoid electrolysis problems in the future.

 

[doghead]

http://interject.com.au/additives-new-2/

 

[AECS]

Thanks for all the info. I hate to admit this, but my screen name, AECS, is my rating, I am an Aircraft Electrician. I have been wiring and repairing aircraft electronics in the Navy for 20 years... But this has me stumped.

Electricaly I know that the grounds are good, I have an aircraft grade bonding strap from the radiator ro the same lug the battery negative wire is at on the passenger side, I have very bright and shinny ground points at all known to me grounds under the hood.

I only get voltage when the truck is turned off, it goes to .015 on the fluke with the truck running. I think that the alternators charging are interupting the hole flow in the phantom circuit, so that is my next search, to check all the wires in the charging circuits.

I did not replace all the coolant, but I will get a PH test done to verify the coolant has not gone to acidic.

Thanks again for all the input.

 

[spectre6000]

I recently had my radiator (original) rebuilt because the electrolysis between the coolant and the lead in the joint solder caused it to effectively fill up with mineral deposits after it sat in storage for so long. It was so full of crap, I'm surprised it flowed at all. You could see the white crystals coming through the solder in the corners on the outside of the radiator such that if it were dipped and the deposits dissolved, it would have leaked like a sieve. This is an issue with our trucks that I think is underappreciated, especially with the lower mileage units like mine that sat in storage for a long time. I went through and replaced or rebuilt everything cooling system related at a not-insignificant expense.

 

[Keith_J]

The aluminum is losing electrons to the iron and copper in the system. You need to electrically isolate the radiator and heater core from the chassis. And use modern coolant rated for aluminum components. Pentosin G12 is an excellent choice, commonly used in Audi/VW automobiles.

 

[AECS]

Keith, that is contrary to everything I have read and learned. The radiator is supposed to be at ground potential. I may be wrong, can you explain a bit more your reasoning?

 

[Keith_J]

This is chemical voltage, the aluminum is oxidizing, electrons are flowing from the aluminum, to the iron/copper parts through the chassis. Over time, this will erode the aluminum as it turns to aluminum hydroxide and or aluminum oxide. Well, it IS protecting the iron and copper from oxidization.

Basically, you have made a short-circuited battery where the coolant is the electrolyte. Yes, the engine block should be bonded to the front battery negative terminal as well as the chassis, that is for the intended electrical system. But aluminum parts of the cooling system should be isolated electrically from the engine block and chassis to prevent electrolytic current flow.

 

[renodogs]

The aluminum is losing electrons to the iron and copper in the system. You need to electrically isolate the radiator and heater core from the chassis. And use modern coolant rated for aluminum components. Pentosin G12 is an excellent choice, commonly used in Audi/VW automobiles.

---------------
That is simply not possible. As long as you are using some form of liquid, it will remain conductive in the electrolysis world given the suspended impurities in the coolant, such as iron. Isolating the radiator much like an insulated/isolated ground used in hospital A/C and computer application power plugs is a nice hypothesis, but in reality, unless you completely eliminate the very fluid you are using to carry away heat, your efforts will be for naught. Therefore, to keep electrolysis down to a minimum, you must monitor the PH in the coolant itself and ensure it is neutral. Basic chemical physics will always win over our best laid plans when dealing with coolant and dissimilar metals. Yes, the iron and aluminium have free electron swaps, but that can be minimized by denying the electrolysis process by running a properly balanced PH coolant. No acid, no electrolysis.

For example: pour Hydrochloric acid on iron and what you will end up with is the chemical result of iron oxide, or better put, iron salt. Salt is the end result of all acid/metal reactions, and electrolysis is just a slow process of the same thing. Aluminium oxide, or AL salt is a natural result of this exchange. This can happen with oxygen and aluminium, or a host of other metals that are ferrous based.

 

[doghead]

I'm surprised you did not use new coolant.

How much was your new radiator?

 

[Keith_J]

No, this is GALVANIC corrosion. Bonding the aluminum to the iron block will accelerate corrosion. Aluminum oxide is an insulator but due to galvanic corrosion, aluminum hydroxide is formed which is more ionic than the oxide and also has a higher dissolution rate, forming a gel in the coolant.

In other words, aluminum IS reactive to WATER, it is only the insulating nature of aluminum oxide that protects it. Yes, new coolant can help.

 

[AECS]

Doghead,

It was 250, and the coolant is being swapped out this weekend. It never occured to me that it would become acidic and create a battery. I live on the base and they don't even like us changing the oil in our driveway let alone antifreeze. So this weekend I will borrow a 20 gallon drip pan from work to completely drain and flush the system.

after driving it today it was over 1 full volt again with no batterys connected and read to ground. Voltage droped as the engine cooled....

 

[doghead]

Coolant is probably one of the most ignored fluids that actually does require constant maintenance and replacement.

 

[RAYZER]

So positive meter lead in the coolant and neg to ground?
I guess it goes without saying, use distilled water in the cooling system.

 

[phil2968]

A short story on my experience with pure water. My dad bought a motorhome. We filled the fresh water tank from his North Georgia hand dug well. The fresh water gauge would not read. I crawled into the cabinet to check the sender. I found 3 sets of stainless steel screws about an inch apart though the wall of the tank. When I shorted the screws together the lights lit up on the gauge. I could not make it read the level on its on.
He went on a trip and used all the water. He refilled in Texas and the gauge worked perfectly.
His water at home was to pure to pass current to make the gauge work. The Texas water had more minerals and it worked! Water, the other component in coolant is very important.
Sometimes tap water could be part of the problem.