If you can be bothered to read it I just copied and paste this from a engineering article of aluminium vs brass radiators.
Galvanic corrosion occurs when an anode metal is in contact with a cathode metal through an electrolyte solution. The anode metal will dissolve and collect on the cathode metal producing an electrical charge as well as destroying the anode metal. This is how a battery works, but is quite destructive to a cooling system. The coolant can act as an electrolyte solution, particularly when tap water is used instead of distilled water and your antifreeze is not changed at the proper intervals. The additives in antifreeze that help protect against corrosion will breakdown which is why your antifreeze must be changed on a regular basis.
Galvanic corrosion requires dissimilar metals, and if you remember from our previous segment,
Construction Differences, a brazed aluminum radiator is all aluminum where as a copper-brass radiator contains copper, brass, and a lead/tin solder. This solder makes a copper-brass radiator more susceptible to galvanic corrosion than aluminum.
If you know a little about the chemistry of aluminum and copper, you may be aware that copper has a higher nobility than aluminum. A metal’s “
nobility” determines whether or not it will corrode when in an electrolyte solution with a dissimilar metal; however, in our case, this is a bit misleading. Copper may have a higher nobility than aluminum, but that simply means it is not the metal that will corrode. Instead, copper will attract the metal that does corrode, which will be the lead/tin in the solder since it has less nobility than copper and brass. When galvanic corrosion does occur, the solder holding the copper-brass core and headers together will deteriorate creating leaks and weak spots within the core.
Since modern vehicles and parts are designed for aluminum components, there is significantly less risk of galvanic corrosion with an aluminum radiator. If you are a die-hard copper-brass radiator fan, you may be tempted to replace the stock aluminum radiator with a copper-brass radiator. This would be an expensive mistake. While your copper-brass radiator would not be at risk of corrosion, all of the aluminum components that your coolant touches will be at significant risk of galvanic corrosion. That’s because, as we mentioned before, aluminum has less nobility than copper; therefore, it will corrode preferentially to the copper-brass. Needless to say, this means expensive repairs to your engine and other components.
Corrosion Review
While there are a few similarities to resisting corrosion between both aluminum and copper-brass radiators, there are some significant differences due to how each is constructed.
- Aluminum
- Radiator is all aluminum thanks to the brazing process, which reduces the risk of corrosion.
- Protective oxide layer is highly resistant to corrosion and self repairing. Aluminum is added to many alloys to enhance corrosion resistance.
- Most modern vehicles are designed for aluminum parts, reducing the risk of galvanic corrosion.
- Copper-Brass
- Radiator is composed of dissimilar metals due to the solder, which increases risk of corrosion.
- Protective oxide layer is not as resiliant as aluminum’s, thus aluminum is often added to some brass alloys to improve corrosion resistance.
- Most modern vehicles are not designed for copper-brass, increasing the risk of galvanic corrosion.
Due to the number of dissimilar metals in a copper-brass radiator, it significantly increases the risk of corrosion in a cooling system. Even if it isn’t the radiator itself that corrodes, it can cause other metal components in the system to corrode. Combining that with the fact that most vehicles and parts are designed around aluminum components, an aluminum radiator has less risk of corrosion than copper-brass.
This segment of our discussion has a significant impact on our over-all look at aluminum vs. copper-brass, but we did allude to the fact that you still have to maintain your antifreeze at regular intervals regardless of which radiator you use. So perhaps there are some differences in maintenance requirements that we need to look at. We’ll tackle exactly that in Part 4 of our discussion.
I'm just trying to wrap my head around it. Never hurts to consider all possibilities.
