Electrolysis and the Fluctuating Ammeter

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 a week of 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.

Thank for the write-up, I wonder how this would work, never needed to use one.

My aluminum thermostat housing is my sacrificial anode, :edgy:

it took 9 years to have to finally replace it. maybe I should check for voltage.

does this apply to only cars with aluminum radiators ?

Not just cars with aluminum radiators.
"Dissimilar metals and alloys have different electrode potentials, and when two or more come into contact in an electrolyte (An electrolyte is a substance that ionizes when dissolved in suitable ionizing solvents such as water), one metal acts as anode and the other as cathode. The electro-potential difference between the dissimilar metals is the driving force for an accelerated attack on the anode member of the galvanic couple. The anode metal dissolves into the electrolyte, and deposit collects on the cathodic metal."
That about sums it up.

Again thanks for posting this, I just installed an RC30 Ve Labs rad cap 16psi to protect my new aluminum radiator. By chance my system has a low 0.19VDC with headlights on but why take a chance? After more research I also dropped in a bottle of NAPA Kool 4056 to control coolant acidity, which plays a role in corrosion.

I'm using an 18psi VE Labs Rad Cap on my '66 D-100 along with the Smart Ground. I also flushed the cooling system with Inter-Ject Coolant Flusher using the "Live" flushing method, that being a round trip to Prescott and back which is about 200 miles. Then I did a water rinse and finally I re-filled the system with purified water, Inter-Ject Electrolysis Arrester and Red Line's Water Wetter. I'll be driving the old D-100 quite a bit over the next few months so I'll post again down the line and let everyone know how everything has worked.

Remember, I am a novice. That meter has been disconnected for years due to risk of fire. Lights are stable at idle.

On the coolant balance, using Ma Mopar's 26 inch copper radiator and conventional green coolant, the balance has been corect for years. It is measurd with the disposable test strips. Two eared factory style 16 lb cap is used.