Just for the record, Electrolysis needs an agent for it to work. In other words just bolting two dissimilar metals together isn't quite enough. Put some water in there btwn the metals and now you have have a Battery which is Electrolysis. Doesn't take much water, moisture out of the air is enough to get things started.
CK5
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Chemical reaction with aluminum heads... blown headgasket
- Thread starter dirtwarrior17
- Start date
This is why changing your coolant at the right intervals and keeping the right mixture is even more critical on engines that use aluminum and iron materials, whether it be intakes or heads.
Take apart a motor that had aluminum components and wasn't maintained correctly, the "erosion" of the aluminum is very evident.
Take apart a motor that had aluminum components and wasn't maintained correctly, the "erosion" of the aluminum is very evident.
dirtwarrior17
Banned
can electrolisis happen on a iron block with iron heads and manifold?
84_Chevy_K10
Banned
dirtwarrior17 said:
Yes, once the additive package in the coolant is gone, it can occur in cast iron engines, too.
dirtwarrior17 said:
Galvanic corrosion can not, by definition, occur with two identical metals. Apparently electrolysis is not the correct term for what we are describing, but in reading the dictionary definition, it sounds like it describes the same thing.
Explanation
Definition Electrolysis
Galvanic chart
84_Chevy_K10
Banned
Dorian,
Radiator is copper.
Radiator is copper.
84_Chevy_K10 said:Dorian,
Radiator is copper.
Who? Any chumps here not running AL radiators? Heh, oh wait, I'm not either.
Yeah, didn't even think about that, yet another dissimilar metal added to the mix. Heater core as well.
84_Chevy_K10
Banned
dyeager535 said:Who? Any chumps here not running AL radiators? Heh, oh wait, I'm not either.
Yeah, didn't even think about that, yet another dissimilar metal added to the mix. Heater core as well.
Yep.
That was the point I was making. No matter what you're going to have several types of metal involved here.
Tim-
I believe you will find that the dissimilar metals must be in a close proximity for the ion transfer necessary for the galvanic process.... Your radiator/heater core is too far away.
As far as electolysis: I think you will find that an electric field must be applied for electolysis, which isn't happening between heads and a block.
-Ben
I believe you will find that the dissimilar metals must be in a close proximity for the ion transfer necessary for the galvanic process.... Your radiator/heater core is too far away.
As far as electolysis: I think you will find that an electric field must be applied for electolysis, which isn't happening between heads and a block.
-Ben
How about the multiple grounds through the block?
The link I provided even for galvanic corrosion mentions electrical contact, and electrolyte, so is that still different than electrolysis?
The link I provided even for galvanic corrosion mentions electrical contact, and electrolyte, so is that still different than electrolysis?
BigBen said:
Negative. As long as an electrolyte is present (coolant), galvanic corrosion can occur. The more conductive the electrolyte, the more distant the two metals can be.
BigBen said:
As Dorian said, the engine is part of the grounding path for the electrical system, therefore it has an electrical charge passing through it.
jarheadk5 said:
Not so fast......
True that the distance varies based on electrolyte, and I must admit that I would have to go do some homework to look up the dielectric constant in coolant..... But we're talking distances of fractions of inches... not inches or feet.
So I'm still pretty sure that the distance between a block and the radiator (through coolant) is sufficiently large enough that when compared to the dielectric constant it is an isolator and not a conductor.... thus taking galvanic corrosion out of the game with the Radiator/Heater Core.
jarheadk5 said:
The engine IS part of the ground path, but all the same ground. Therefore there is no electrical potential between these parts (The whole point of a "chassis ground")... and no electrolysis.
BigBen said:
I knew this textbook would come in handy at some point, even though I already know most of what's in it...
From Chapter 12 - Cleaning and Corrosion - of the "A&P Technician General Textbook" by Jeppesen-Sanderson:
One of the basic characteristics of metals is their electrode potential. In other words, when two dissimilar metals are placed in an electrolyte, an electrical potential exists. This potential forces electrons in the more negative material, the anode, to flow to the less negative material, the cathode, when a conductive path is provided. As discussed earlier, corrosion occurs when electrons leave an element.
For the record, I understand what you're saying, but all it takes is a path. Old coolant, with wear particles from the waterpump and minerals from tapwater, is going to be that path. It won't be an efficient path, but it'll be a path nonetheless. The effects will be far more noticeable on parts that are closest together, i.e. Al heads and/or waterpump on an Fe block. Aluminum will be damaged the most, because it is more anodic than iron or steel. The radiator & heater core will get their corrosion damage from the mineral deposits they collect from the coolant.
jarheadk5 said:
BigBen said:
My above-quoted statement is incorrect. What I should have said was "since the engine is part of the grounding path for the electrical system, it has electrons flowing through it." Since electron flow is the basis of corrosion in general, and galvanic corrosion in particular, the fact that the engine is part of the grounding path makes it more prone to corrosion than if it were not.
