Blade switch on the battery will keep electricity from speeding up galvanism. Good to flip the switch every time the car is parked. Easy to reach from the driver’s seat with your feet out the door when getting in or out. Water heaters all have a sacrificial anode; seems like a good idea for any metal tank with water in it. I’ve seen them hanging from radiator caps as well as for the drain hole.
Charlie

 

The coolant in my 68 is a dielectric. It's pure ethylene glycol. There is no water in the system. There has been no water in the coolant since 1974. I pulled the original engine and stock aluminum radiator to install a GM ZZ4 and a BeCool aluminum radiator. The engine passages had no rust in them....they were coated with a white dust that was left there by the silicates added to the pure antifreeze. The 35 year old radiator showed no signs of corrosion.

The original factory aluminum radiator was leaking in 1974 due probably to the original owner using water in the radiator. An acquaintance at the time was in the Army Reserve and served as a tank engine mechanic. The tank engine was derived from an aluminum aircraft engine. They were required to use pure ethylene glycol in the cooling system to prevent......corrosion. I've followed his advice ever since.

I've used pure ethylene glycol in my 1997 Thunderbird daily driver since I've owned it. My wife wanted me to buy the car since it looked like my 1990 Ford Australian Falcon. No corrosion. Drove my 1995 Caddilac, inherited from my father, for about 10 years with pure ethylene glycol also.

A great advantage of using pure ethylene glycol is that it doesn't boil at temperatures below ~300 degrees F. This means that the cooling system is never pressurized. Much much less problems with leaks. My Third serpentine belt broke on the freeway. The engine temp was pegged before I could pull off at the side the road. Immediately looking at the engine to see the broken serpentine, the coolant hoses were very hot, but not pressurized.

Also, my 68 brake system is waterless. Silicon brake fluid to prevent water absorption.

 

I agree with those who don't see a problem because GM did not ground the radiators in the first place. You should not have to do that as it has not been a common issue for Corvettes. I have an aluminum radiator and it has a large shroud with the two 11" Spal fans. For controlling the cooling fans I have the DeRale PWM Electric Cooling Fan Controller.

While In college in Fort Myers, Florida I lived on a 36' boat and learned more than I wanted too about corrosion. They put Zinc Sacrificial Electrodes on the out drive when it is made from aluminum. For the fiberglass Hull we used Copper Bottom paint but on anything aluminum you need to apply a special paint and renew any zincs that showed evidence of breaking down. A new boat moved in and withing weeks there were issues. Someone had his Neutral and Ground reversed in his A/C Electrical system and whatever he had done his neighbors all watched their anodes melt away in days. They inspected his wiring and found the problem. I am glad they found it quickly as I was three boats away from him and my aluminum was protected by the zinc.

I have told this story before but for those who missed it. My neighbor was an old Navy guy and bought a new Sears and Roebuck 12" Aluminum skiff to use as a dinghy for his 51' Sailboat. One of the first things he did was tape out the waterline and then he painted it with the regular Bottom paint that had a high percentage of Copper in it. You are not supposed to do this as the copper in the standard Marine Bottom paint ate away the aluminum so fast that the next day we could push our fingers through the hull. There are different types of paints and procedures for Wood Hulls, Fiberglass Hulls and Steel or aluminum Hulls.

Recently another member sent me an article that suggest that Distilled Water is not quite as good as using Reverse Osmosis water inside the cooling loop. From now on I will be using the R/O water inside my cooling system. One of the most important things is to flush your cooling system every five years or so and replace the radiator cap when you flush the radiator.

 

I agree that you should not need a ground on the radiator.

Until the day you develop an electrical issue cause a part wears out, and your coolant flush is a couple years old, and capable of conduction..
It would take both to have a problem.

 

So, here's one of two leaks, can't see the other as it's on one of the center tubes. If you zoom in on the second tube from the left you can see a tiny crack right on the tank where the tube meets the tank.
This is what happened to my old Rad. I have a anode that fits in the drain plug that I will install in the new one. I believe although I have gotten so much conflicting information about grounding I will follow Leigh's advice and put a ground wire on it. I was going to pour my coolant back in. Nothing but distilled water and prestone. It looks super clean and isn't very old. But after reading all of this new fresh coolant it is. After install I will indeed take voltage readings.

 

The aluminum will want to be the positive anode if you let it. All you can do is not let the antifreeze conduct, and ground the aluminum. In a corvette, it is not a matter of IF you will ever have a ground issue in the car, but WHEN. Solder and AL have their own galvanic issue, and they touch! So you need to prevent the electricity from flowing.

I am sorry you had this happen.
Here is an article that discusses it fairly well:
link
In your case I would check carefully for what that article causes "Stray Voltage" . In a Corvette it is probably due to a bad ground somewhere.

It bit me once too.
I had a Ford Taurus SHO since almost new. Cool driving car but a PITA repair nightmare. No coolant issues for six years. Then it ate two aluminum heater cores in a six month period. Solder joint leak like yours at a fin. Obviously something had changed in the car. I presumed it was an electrical issue, I tried all the tests & fixes and could not find it. I was highly motivated, changing the heater core on that car was a ****. Entire dash must be removed, steering column, both front seats. 2 day job. Did not want to do that a third time. I would have torched / sold the car instead. Changed it to a copper heater core, grounded it, and never had another problem with that for another 10 years. Rad was fine. Fresh antifreeze. No zinc anode. So I cannot say for sure the ground fixed it. But even the best freshest& antifreeze mix will conduct electricity, at least a little bit, and the aluminum is the weakest link.

 

So I made up this.

And I threaded it into the lower fitting for a fun sucker coolant line.


Radiator grounded. Filled system and burbed out air this evening. Will take voltage readings tomorrow.

 

I can tell you that if you have a computer controlled C3 and your radiator is grounded... You WILL have issues at some point in driveablity when the voltage starts going up in the radiator fluid, causing the CTS sensor to go batshit crazy. I have had several calls about this type of issue over the years and the problem was always rotted out insulators at the bottom of the radiator. Voltage usually was in the 3-5vdc range and CTS sensor usually goes cold reading of around -32*F when it's 70*F and pouring tons of gas down the TBs on an 82 C3. Just a bit of tidbit info for the CFI crowd that isn't in the GM service manual. Check your voltage of the fluid.

 

Interesting information about the coolant temp sensor. And I do respect your opinion Buccaneer.
However, I have been advised all over the internet that voltage readings above .3 of a volt are damaging. And your talking 3 volts and higher in the coolant. Should never be higher than .5 of a volt.
As I do run a CTS I will indeed heed your warnings.
As I am constantly working on one thing or another on my car. Seems my coolant never gets old. However in the past I always tested coolant using a strength of mixture tester. Didn't know to test low voltage. But then I never before had a issue like this before.
One gentleman in another thread mentioned that his DeWitts Radiator came with a ground connection on the lower rail.
As I stated when I started this thread, I have read a ton of information all over the internet on this topic.
Seems split down the middle as to grounding a radiator or not.
I would be out in the garage taking voltage readings right now if it wasn't for a sleeping grandchild. My car shakes the whole house. So I'm waiting for the toddler to wake.

 

Thanks and you are absolutely correct. 3-5vdc is HUGE for a voltage and can be damaging and IMO, anything over .2 is a lot, but that's what the readings were and it was causing VERY bad issues with the CTS sensor and the ECM. When electrolysis starts and left unchecked due to maintenance neglect, this WILL cause issues. At first, they thought I was crazy asking about coolant voltages, this was a corvette shop no-less. I made them a believer though.

To prove a point in one case, I asked what the CTS temp was reading in ambient temp, pretty close to normal readings. Then inserted into the engine, data stream was way negative reading, thus the huge amount of fuel dumping into the engine, the ECM thinking from the cold CTS data being sent to the ECM it was a very cold engine and it wasn't. I've seen some odd stuff over the years with CFI that isn't in the GM manual.

 

I have seen first hand the effects of a defective ETS. Or CTS depending on the engine style. Bottom line, sometimes this won't even throw a code. The ECU just thinks it's cold.
However, back to brass tacks as it were. Radiator grounding.
Coolant that over due for maintenance is going to find a ground whether the radiator is grounded or not. The engine block is well grounded and needs to be.
The idea of a ground on the radiator is about saving the precious radiator.
When voltage gets that high in the coolant. I would think there are multiple issues. Poor grounding of the engine block, poor grounding of other electrical accessories, etc. As well as old coolant.

 

Well the toddler finally woke up and I could shake the house.
took the following readings.
Car turned off, .520 mV.
Car turned on, radio and blower fan running, Same.
Car running, low load, .530 mV.
Car running, high beams on, fans running, high load on Alternator, .630 mV.
A.C. readings. Both low and high loads, 0.
These readings in mili volts show almost no voltage in the coolant whatsoever. In fact a lot of cheaper meters wouldn't even measure this low.
I'm thinking I'm good to go. New rad, fresh coolant, sacrificial anode in the rad. New ground wire just in case. And Voltage less than 1,000ths of a volt.

 

OK anybody ready for Chemistry review class?
If not skip this post LOL.

I'll bring this down to the most basic level. We won't be calculating any voltages or anything!

This is a galvanic series chart. It is why batteries work. Two dissimilar metals make a battery, and electrons flow.
The metal at the top of the chart wants to be the anode. This is the one that gets dissolved.

So in a copper rad / iron block system, the iron is higher on the chart, is more noble, it will be the one that gets dissolved, it becomes the (negative) anode. (Like the zinc on the left in the pic below) And there is a .2V "potential" between them.
IF ELECTRICITY is allowed to flow, or the two metals come into contact with each other, electricity (electrons) will flow.
In this case the (-) electrons will leave the iron metal / engine block, which creates (+) charged iron ions (Fe+3), which dissolve off the engine block, and these charged particles now float around in the liquid coolant, and make the water more conductive than it was before.
Guess where these dissolved Fe+3 ions want to go? That's right the (+) copper cathode/radiator. The collection of pos ions on the cathode makes it positive, so it attracts the (-) electrons thru the return circuit, like a vacuum.
.
How do the electrons get from the anode to the cathode? They travel via an electrical wire, current flows. Via metal to metal contact. In this case of a car, they travel along thru the rubber, which has dirt coatings on it. Or thru the rubber itself. If you rub the rubber with moving ions (water flow) you will create a static charge which will take the stuff on the rubber conductive. The dirt or deposits are what actually let the electrons travel. The electrons get back to the copper radiator, which becomes the (pos) charged cathode. There are some negative ions are created, which travel in reverse, (things like oxides and carbonates which are not as damaging).( But I figured that would just confuse.) As the iron (+3) ions find electrons at the copper cathode, they turn back into solid iron (neutral) and coat the copper radiator. That is the rusty brown (iron oxide coating) you always see inside copper radiators. It looks like "rust" because it is. It came from the engine block. Did you ever notice the inside of the rad hoses have the same brown coating? Came from the engine block, and makes the rad hoses conductive like a wire, and lets the electrons go back. So you can not prevent the electrons from getting back. With new hoses maybe, but not for long. The negative ions also carry negative electrons back, so even new hoses does not help much.

But when you switch the radiator to aluminum, it is higher on the galvanic series chart than the iron block. So everything reverses. The situation with the metals reverses. If they are electrically connected, the aluminum will want to be the neg anode, left on the pic below, and it will give up electrons to the return wire. As the aluminum metal loses electrons, those (neutral) atoms turn into Al+3 ions, and aluminum leaves the radiator, one atom at a time. And then it deposits on the engine block, which is on the right in the pic below. It is now the cathode, because aluminum is higher on the galvanic series chart. And the the difference between them is not only reversed, it has a "potential" voltage difference of .3 to .4V. So the "battery or galvanic action" is twice as strong in this aluminum / iron system, than it was before in the copper / iron system.

So to prevent this you could "cut the wire" preventing the electrical circuit. Easy if it is a real wire. But since the oxide coatings on the rad hoses are enabling them to conduct, only fresh rad hoses will do that. Also those pesky negative ions. With fresh hoses and fresh solution, the process is ridiculously slow. But the liquid solution becomes more and more conductive as things dissolve, and the process speeds up. You need to keep the glycol mix non-conductive, by using only pure distilled or deionized water in it, and having a rust inhibitor to protect the metals. But it will deteriorate anyway. So it needs freshened regularly, to keep the charged ion content low. This ion content shows up very easily as voltage on your multi-meter. That is the easiest way to "separate" the two metals, electrically speaking.

If anyone is interested, I could set up a demo video. I haven't done that sort of thing in a year or so since I retired from the chem lab teaching.

Regular tap water greatly complicates the whole situation, because it contains carbonate, which very easily turns into negative ions, and makes rock hard white concrete scale. The stuff you see in hot water heaters.




What you do not want is for your nice aluminum radiator to take the place of the zinc in the pic above, and look corroded like that zinc.
Zinc is the best because it will always dissolve. So throw some of that in the system and you got the AL rad covered.

The ground wire trick works, because in a chemical battery, the positive terminal is the cathode, and the negative ground is the anode. Our Aluminum radiator is also a neg anode. The electrons are attracted to the ground on the battery. If the ground wire, is connected to the al radiator, has a good connection to the neg battery terminal, and is a much better conductor than the hopefully only weakly ionized glycol water solution, ( think of it as a very skinny wire), so it easily drains off the (-) electrons or sucks them back to back to the battery, preventing them from going thru the more difficult or "restricted" trip, thru the glycol mix. Electricity will always take the path of least resistance. So even if your glycol mix is getting old, your rad ground wire conducts much better, and the electrons go that way, because it is easier. The car's battery is kind of like a big vacuum cleaner sucking the electrons off the AL rad, and sending them to the battery, and NOT back to the engine block. The car's battery is another whole loop off to the side. We have two loops. We want to starve this one. So we deprive the engine block of it's electron return flow, and that stops the anode corrosion. We cut the "wire" above. No aluminum ions created, no negative ions created either, no solid metal aluminum atoms leave the radiator. Aluminum rad saved. Same thing with whatever electrical gadget is creating (-) electrons or static, and pumping them out thru the engine block. That part's own ground needs to be the easiest way for the electrons to get back to the battery. We need to make the glycol return way difficult, and the ground wire electron return path much easier.

Having both is like a two pronged protection approach:
(1) distilled water / non-conductive glycol stops the ion flow in the "salt bridge" loop above and (2) the ground wire on the rad deprives the engine block of it's electron return flow, cutting the "wire" return loop above. The zinc chunk in the rad is a 3rd level of protection, because it wants to be the anode. For as long as it lasts. The faster it corrodes away, the more battery action you have going on in your coolant.

Honestly, I tried to make it simple. Electro-chemistry is a College level subject!
It was a 4-8 student AP Chem Class I taught in high school!
If you read all this, and understood 75%, you just graduated!

 

I think you are good now. Great in fact!
It is too bad you did not measure the old glycol out before you changed it.
Hmmm... maybe I'll go check the glycol in my 30 year old S-10 pickup, because that truck really gets abused and neglected.
It might give us some good mV data.

 

Well, it could have been interesting data indeed had I taken voltage measurements before I drained the old rad. But I didn't know at the time. That was the reason for this thread. To learn.
Today I know a lot more than I did almost 3 weeks ago when I found 2 very slight leaks in my 2 year old radiator.
But truthfully, that coolant wasn't very old. I had changed a waterpump maybe a year ago. If it was that long ago. And the system was flushed and filled with fresh coolant at that time. And that coolant was only about a year old as that radiator was installed just under 2 years ago.
Did my rad leak because of electrolysis? Or was it just not made sturdy enough? Not certain I'll ever be certain. But it's been a real inconvenience. So I'm doing whatever I can to ensure this one will last.
Time will tell.

 

Yeah it could have had a thin spot.
You did do the zinc anode also right?
Now it is like you put three "safety chains" on it.
I don't think it is going to roll-off-the-trailer no matter what.
You should be good!

 

Thanks @leigh1322! That was a fascinating read.

It seems that the best thing you can do to protect your aluminum radiator is to do a proper LS swap. Aluminum radiator + aluminum heads? Everyone has that. You need the aluminum block, too, which are only the numbered LS engines, plus a few like the L33. Check your zinc at every oil change.

That was really interesting to see a DeWitts radiator with a ground spade. I need to look harder at my truck (C5 contemporary, but with an iron block), and see if there is something similar.

EDIT: No ground on the truck radiator, as far as I can see.

 

I've been procrastinating changing the coolant in my 2017 GMC truck that just hit 100k miles. After reading this whole thread I'm ordering some new GM coolant today!

 

Dewitts on Radiators:

They suggest distilled water and they do not think grounds are a problem, they even recommend one. Their coolant has an additive package is greatly improved vs normal green coolant, and the non-propylene glycol formula has better heat transfer properties than p-glycol.

What coolant do you recommend?

Actually the quality of the water you use is more important than the brand of coolant. Aluminum is very sensitive to minerals and chemicals in all sources of water, and only distilled water should be used. We recommend that you purchase a "pre-mixed" extended life coolant of your choice. This eliminates any chance of using the wrong source of water and simplifies the process of mixing, filling, and adding coolant. A coolant recommendation sheet will come with all new radiators and you can download this sheet by clicking here.

Why are my electric fans not running?

When you purchase a DeWitts Radiator & Fan Combination, we install the temperature switch (195on/175off) into the radiator inlet tank. When the temperature hits 195, this switch contact closes and the fans will come on. In order for this to function correctly, the radiator much be properly grounded. A ground strap is provided on each package and the installer must connect this wire to a good chassis ground or the fans will not function. If your fans were operating and then stopped working, a good test is to remove the wire from the switch and touch it to a good ground. If the fans come on, then the problem is likely the switch. If the fans do not come on, then check the main fuse for each fan.

 

A huge public Thank You to Leigh, our resident scientist and all around good car guy!
So basically speaking it looks as though DeWitts has a ground on their radiators for a temp sender more so than a electrolysis preventer.
I understand that DeWitts is a leader in the quality aftermarket radiator industry. And by all accounts they do seem to make a quality product. However what Leigh has put up does not show them addressing the issue of electrolysis.
Perhaps they don't see this as a real issue.
And if you look all over the internet, you will find much discussion on the topic, and many opinions.
I'm glad I started this thread. As in this thread we have also witnessed 2 opposing views on the topic.
Myself, I'm following Leigh's advice. I believe he's a pretty sharp guy. And he has helped me out before.
Anyone with any real data to support what they believe to be the correct answer.
Please post away.
We are here to learn.