Electrolysis and the Fluctuating Ammeter

[Top End Dean]

I've had close to 60 old Mopars over the years and some had electrolysis related problems. And some with this "Dancing/twitching amp meter" issue, which by itself never really seemed to cause any problems other than the headlights surging at idle. I never realized that electrolysis and that dancing needle could be related, or that they could cause some very expensive damage to my pride and joy by way of electrolysis in the cooling system. This info applies to A-B-E-C bodies, Pick-ups and Vans so first I'll give you the rundown on what I was working on and then what fixed it.
I had owned my 1966 Dodge D-100 for about a year with the original 225 and 3 on the tree, it had the "Dancing/twitching amp meter" from day one. After that first year I updated to a 440 with Edelbrock heads and Intake, aluminum water pump and MP housing, a new Ron Davis aluminum radiator and a 4 speed. I rebuilt the original starter and alternator at Gen Star in Glendale and I had told Gary about the twitchy amp meter when I dropped them off. When I picked them up he said the alt had a loose stator plate and that could cause the twitchy needle.(?It's been a while but I think that's what he said?) BTW the engine compartment had been completely stripped and repainted too. So I fire up the all new engine and Waa Laa, the same twitchy needle. Now what? Well, I've never had any damage from this issue before right? So when I have some extra time I'll take care of it. Fast forward a year and out of no where I start getting little specs of coolant on the engine and air cleaner. Where the hell is it coming from? Several weeks later and a lot of inspecting I finally get my answer. My expensive aluminum radiator has several tiny pin holes in it. WTH?
So I suddenly remember what the guy at Ron Davis told me about checking for voltage in the coolant IMMEDIATELY after starting your car for the first time with the new aluminum radiator. Yep. I didn't follow that advice and it cost me dearly. So I bought a VOM (Volt/Ohm meter) and tested my system. With every electrical system on, headlights on high beam, heater blower on high, radio, etc I was reading 3 volts in the coolant! Yes THREE volts. I was also getting a 2-3 volt spike when the starter was engaged. In a stock cast iron engine with a brass/copper radiator it's not that much of an issue. But if there are aluminum components in the system it's a BIG issue. After cleaning and upgrading grounds and cleaning the rusty clips in the fuse block I got it down to .3 volt. I was still getting a .8 volt spike when the starter was engaged but it was much better than before. The twitchy needle issue was still there though. I talked to Gary in between all this and he had given me a few suggestions like running a jumper from the regulator to the battery and or removing one fuse at a time to help narrow down the problem. Then one other thing he said about the ignition switch having too much resistance in it occurred to me. I had two new switches on the shelve so I changed it out and BAM! No more twitchy needle and ZERO VOLTAGE in the coolant. All this time it was an other wise perfectly operating original ignition switch. In the end there were many things that contributed to this problem, but the switch was the root cause. I hope this helps other people out there with this issue before they lose any expensive components like I did. I know there are many of you who have dealt with one or both of these issues so please chime in with your experiences with Electrolysis and the fluctuating ammeter!

Here are two very good links with knowledge and info about this problem. The first has a lot of knowledge info and the second has some great products to help fight this demon as well!!! Hope this helps!

http://www.sancarlosradiator.com/VoltageDrop/index.html
http://www.ve-labs.net/

Keyword: Electrolysis, Ammeter, Electrical system, Cooling system.

 

[autoxcuda]

Key was the first step in checking electrolysis. Second was being persistent to remove it and finding the root cause.

Thank you so much for posting the whole experience.

This is 76 mV or .076 volts. My system: Reverse osmosis water, Justice Brothers Super Radiator Cooler (RC22p), and Justice Brothers Cooling System Protector (CSP/1p)

Two year later it was in the mid 80's mV. I had to drain it to remove a cylinder head.

 

[Abodybomber]

Excellent post, thanks for the info. (nice diagnosis work!) So used to this, on" feedback " era cars, never thought about it on muscle car era equipment,. As we add newer upgrades on older cars, something to think about.

 

[RedFish]

Old coolant will show more voltage than fresh coolant even in new cars that have a much different system ( more grounds routed back to the battery via a wire ).
They say one can test coolant with a volts meter. More than 4 tenths of a volt at 2000 rpm means replace the coolant. I don't know if one could get a reading that low in a classic car.

 

[Abodybomber]

Old coolant will show more voltage than fresh coolant even in new cars that have a much different system ( more grounds routed back to the battery via a wire ).
They say one can test coolant with a volts meter. More than 4 tenths of a volt means replace the coolant.

Correct.

 

[67Dart273]

What you are describing is not "exactly" electrolysis. Electrolysis is sort of just exactly what it "says", that is, you are creating a battery by means of "dissimilar metals" and an electrolyte, AKA your coolant.

In other words the block, and whatever the radiator is made of, plus the coolant, have become a battery.

That is not exactly what is going on, with what you describe here. What YOU have is a (vehicle) battery / grounding/ charging problem.

Now you very well COULD have electrolysis, as well. But the readings you are getting re: the alternator and starter are purely electrical system.

My first thought is that TOO SMALL battery main ground along with poor engine to body grounds

However, your readings CERTAINLY are something to think about. There is no doubt that "twitchy alternator" could cause damage as you describe.

 

[autoxcuda]

Old coolant will show more voltage than fresh coolant even in new cars that have a much different system ( more grounds routed back to the battery via a wire ).
They say one can test coolant with a volts meter. More than 4 tenths of a volt at 2000 rpm means replace the coolant. I don't know if one could get a reading that low in a classic car.

What I have seen fairly consistent in the Automotive Repair industry trade magazine technical articles and in boxes of new heater cores is 3 tenths of a volt (300mV).

I have less than 1 tenth of a volt in my 1968 Barracuda (.086 Volt or 86mV pictured above). :dontknow:

I agree with 67Dart273 that the huge 3 volts was mostly not from electrolysis (if at all). It was from poor grounds and a faulty ignition switch.

Maybe we shouldn't be calling this a electrolysis test so much as it is a test for stray voltage in the coolant system.

Just we should periodically check for voltage with a test light or voltmeter in series with the battery ground terminal with all the electrical draw turned/taken off and ignition off.

 

[67Dart273]

AutoX I would assume that measuring for electrolysis / chemical voltage is normally done with the engine off? In fact I would assume the car battery could be disconnected.

 

[autoxcuda]

AutoX I would assume that measuring for electrolysis / chemical voltage is normally done with the engine off? In fact I would assume the car battery could be disconnected.

I've always seen/done it with the battery connected. My published articles don't specifically say connected or not. But if they don't specifically say to disconnect the battery, I think it's safe to say they want it connected.

But I see what you are saying about disconnecting the battery to eliminate the grounding and electrical system issues and focusing on the coolant itself.

I see value doing it with the engine off and on. That's how the original poster found he had a bad ignition switch.