1badtantrum

My brand new Aluminum aftermarket radiator (2009 C6Z06) accumulated dozens of holes mostly sitting in the garage...Culprit, radiator electrolysis. I made a battery or a plating device and didn't even know it. Radiator (brand new) was installed in March 2016. Engine was new so no existing fluid in block. Fluid fill consisted of 2 bottles of Red line water wetter and store bought deionized water. After dyno break in and 2 track events ~6 hours of run time with about 2.5 months summer storage time the radiator was riddled with holes across the horizontal aluminum cooling tubes.
Background:
I was prepping the car for the upcoming track days. I noticed my overflow tank was completely empty. Weird, but I was messing with things over the summer and remember adjusting some hose clamps. No big deal, just add some fluid. Added 1 bottle of water wetter and started to add deionized water and fluid was dripping down on the floor. Car was on jack stands so I looked under and fluid was running out of dozens of holes across the bottom half of the brand new in March radiator. Called the manufacturer to explain my defective radiator and then we were discussing the failure details and I began my radiator electrolysis education.
Diagnosis/Debug:
After consulting the radiator manufacturer, daughter (fresh out of chemistry), battery engineer and friends, I tried some things, measured potentials and think I have a solution. I removed the radiator and thermostat then flushed the coolant fluid from the block. I took many voltage measurements around the engine, frame, radiator mount, etc. The car has an emergency 'cut-off' switch which isolates the battery (+) from the car. I took measurements with the battery physically disconnected from the car and measurements with the safety solenoid off in the normal shut down state the car sits in. All voltages were '0.000' with respect to the ground terminal in the rear of the car. I installed the new radiator in the car and measured the voltage of the radiator, engine, etc. All reading were '0.000' volts. I added Royal Purple, purple ice and by there recommendations, filtered drinking water (store bought). I measured the PH of the store bought drinking water and it was ~6.7. Acid is known to exacerbate electrolysis, 6.7 is only just barely acidic. I then measured the voltage of the aluminum radiator (Vrad) to ground. Uh-oh...Vrad=-0.520V. The voltage of the fluid in the overflow tank (Voflow) and Voflow=-0.207V I was so alarmed by this, I immediately drained the fluid and flushed the $20 Purple ice and $8 of water out of the cooling system.
After discussing my chemistry experiment I decided to try antifreeze and see if it's chemical buffer properties would help. After flushing, reconnecting plumbing and filling cooling system with about a 50/50 antifreeze and deionized water. I measured the radiator and found Vrad=-0.383 to -0.410V and the voltage of the fluid Voflow=-0.090
Since I have removed the transmission lines from my radiator, I pulled out the original transmission lines and looked at the connectivity with the original radiator and trans. It appears that the original radiator is in fact grounded through the transmission lines to the transmission, to engine ground, frame ground etc. The grounding of the radiator is a debated topic. After looking at the stock trans lines etc. I grounded the radiator tank using the supplied fan mounting bolts via some 12 gauge wire to the frame ground points on the frame rail. After grounding of course the radiator voltage Vrad=0.000V, the fluid voltage Voflow=+0.069V. Ungrounding the tank would quickly see the voltage ramp (or drop if you consider polarity) to Vrad=-0.370V and the fluid Voflow=-0.050V.
I connected the radiator to ground and left if for the evening. Voltage after stabilizing for 14 hours was Vrad=0.000V and Voflow=+0.080V

Since I would really like to run without antifreeze, I may flush the system and go back to deionized water with the tank grounded and take measurements. I can't afford to buy a radiator every 5 months.

Any thoughts or experience are appreciated.

RX-Ben

Interesting. You certainly are not the only one with an aftermarket radiator so this issue seems to be relatively rare.
You can get a sacrificial anode for <$15 - swap it in for the drain petcock.

1badtantrum

Agreed...quite rare. The only noteable difference is the lack of grounding via the transmission lines. The block was resleeved, so perhaps the new iron sleeves are more 'reactive'. Thanks for the sacrificial anode thought. I did consider but since grounding the radiator tank, I'm similar to the stock grounding setup and all seems well.

phipp85

That is certainly an interesting chain of events. At least it was a simple fix via a cheap grounding wire. Well if you don't include the new radiator cost its cheap.

RX-Ben

And grounding the radiator is typically a recipe for galvanic corrosion, but my guess is that in this case, it corrects the attenuated grounding that was occurring between the radiator and the diff/trans/rear chassis.
Are the cooling lines that connect to the radiator actually hard lines, all the way to the diff/trans/heat exchanger, or are there rubber flex sections?

phipp85

They have some short sections of rubber.

RX-Ben

Are they grounded via support brackets?

phipp85

Yes. One on the block and two or three along the torque tube. I replaced mine with starlite hose and AN fittings.