Coolant tube/pipe galvanic corrosion?

[ambrynmc]

So there is one item that I haven't seen anyone address and I'm not sure if it is a real problem or if I'm just over-thinking it...galvanic corrosion (GC) in the cooling system.
Based on what I was taught, if you have to use different metals together on anything, you should check their compatibility on a GC chart, like the one below…
If the two metals are close together, they will have a lower chance of eating one another. If the two metals are far apart, they will try to destroy each other (I’m over simplifying…). On this chart, any combination below the red line is not recommended.
Based on this, an aluminum engine is most compatible with aluminum (duh) and steel. The worst metal choice is stainless, followed by nickel and copper. This leads me to my actual question, does any of this even matter? I’ve seen several conversions that used copper-probably because it is easy to fabricate and stainless-probably because everyone thinks “stainless is the best” (except in this case). Has anyone experienced any problems with copper or stainless?
I know that you should check your coolant “voltage” to make sure there is little to no voltage potential in it to help reduce GC. I know you can monitor and /or test your coolant to, but I don’t know anyone that does this. Any thoughts on this?

[Buggin_74]

It's one of those things where in theory and in practice are two very different things.

I've been running mine for years with stainless pipes and aluminium header tank and they still look like new inside when i swapped engines a few months ago.
Although they are all isolated from each other by rubber hose.

Galvanised water pipe is meant to be the worst yet my rotary bug built in the 80s was still fine inside when I ripped all the pipes out in about 2001.

As long as you use quality coolants which have all the corrosion inhibitors in them anyway and change on regular basis there shouldn't be any issues.

[Ol'fogasaurus]

There was a move a while back to put a sacrificial anode or something like that in the top of the radiator but I never head much about it after that. It is a problem with boats moored in a marina where running water is (like a river going into salt water) or where someone moored near by hooked up to shore power has a bad electrical system in their boat causing problems for others but again, I haven't heard much squawking about it for a while.

Lee

[ambrynmc]

As long as you use quality coolants which have all the corrosion inhibitors in them anyway and change on regular basis there shouldn't be any issues.

I was starting to think that might be the case. So change the coolant every 2 years (or as recommended) and you're good

[CobraJet]

It's one of those things where in theory and in practice are two very different things.

I've been running mine for years with stainless pipes and aluminium header tank and they still look like new inside when i swapped engines a few months ago.
Although they are all isolated from each other by rubber hose.......

I'm a retired Plumber that has seen the results of galvanic corrosion many times when people fix old leaking galvanized pipe with copper pipe. Just about every problem I've had to repair had to do with the person not properly electrically isolating the copper from the galvanized. This allowed the two metals in contact to flow a minute amount of electricity. In effect they acted as a mini battery of sorts!

A common way to eliminate this problem is to not have a continous electrical path between the two different metals. The easiest way to do this is to use a dielectric coupler.

On our auto coolant systems this can be done by simply using rubber or silicon hoses between the different metal types.

[Snyiper]

Hmmm metals are not touching but the coolant/water is compleating the circut for the electrolisis...

[falcor]

The surface area of the metals are also a factor on how agressive the Galvanic reacion will be, a small stainless area to a large aluminum is less dangerous than a small aluminium area to a large stainless one.

[perrib]

Distilled water and phospate free coolant would be your best defense.