Ground Your Aluminum Cooling System Components!
 

I have noticed that more and more of my customers' radiators inlcude a ground strap. One of my most knowledgable shopowners told me today that he grounds ALL aluminum radiators and heater cores. He said that he was having heater core failures within two weeks of installation and after he grounded them, the failures stopped. Just thought I'd pass it along.

That's strange, one normally insulates dissimilar metals to avoid setting up a galvanic reaction. Do you know what they are trying to accomplish?

yep. i agree with craig.

cant see any benefit to grounding them.

tom w

I agree. An aluminum radiator in contact with a dissimilar metal via the coolant, which is a weak electolyte, constitutes a galvanic cell.

If you "short" the dissimilar metals together, galvanic corrosion will be faster. Most radiators in my experience are electrically isolated from vehicle ground so the "short" doesn't happen.

See any basic chemistry text. The above concept is at about 300 years old.

Duke

Then how about a sacrificial anode ?


.

That would be the aluminum itself, hence the failures.

The above concept is at about 300 years old. Yes, it is very well known, but why did Mercedes' engineers build the original W124 evaporator core of aluminum and copper thus assuring the failure of a part that requires the removal of the entire instrument panel to R&R?
regards,
Mark

probably because it was cheaper (than an all copper one) and they didn't consider the chemistry at the time.

Just like the damn fuses!

why aluminum evaporators fail
 

The failure mechanism in the saga of A/C evaporators is metal fatigue cracking. The very thin stamped aluminum heat exchanger plates had a sharp crease at the bends (German precision stamping die?), and the repeated hot-cold-hot expansion and contraction from off-to -on-to off eventually leads to cracking--and leaking. Aluminum will work harden much more than copper.

This is NOT to say radiators and heater cores don't fail from internal corrosion (or erosion)--they DO! It is a real technical challenge to keep the entire cooling system protected and free of corrosion and mineral deposits. There is cast iron, polished steel, brass, copper, aluminum, magnesium, stainless steel, some oil likely, heat, high turbulence, boiling at times on the hot surfaces, extreme cold in the radiator (causes mineral deposition),etc

Moden 'coolants' do a great job.

Gentlemen, I am not a chemist nor a metalurgist, and unlike many of you, I do not pretend to be. I was merely passing along the result of experience from someone who makes a living working on cars and my own obseverations of the replacement parts that they use to do so. I only cited engine cooling systems. Evaporators were not part of my alert. Some of you take things out of context. If you don't think it's a legitimate problem, then simply ignore it. For those willing to learn there is a GM TSB on the subject. It has to do with Dexcool becoming electrically charged and internal arcing burning tiny holes in the aluminum cooling system components. However, you might be successful in preventing the problem simply by ignoring it. Parts are warranted, your labor is free.

I, for one, do not doubt what you've observed, I'm simply trying to understand the purpose of grounding the radiator. Assuming that the concern is galvanic type corrosion due to the dissimilar metals, grounding does not make sense. If there is a different concern related to the radiator "becoming charged" then grounding may be a reasonable solution. I have never heard of cooling system components becoming charged, do you have any info on this TSB, it sounds interesting.

I'll try to get the specific TSB number. One of my customers ( a GM service manager) told me he would look it up for me.

Thanks:)