ARCHIVE Wits' End- I really hate galvanic corrosion

[80JDM]

Let's do an experiment?

Let's take 2 plates the same size unpainted untreated, 1 from carbon steel and 1 from Aluminum (Al)

Let's put them outside in the garden, exposed to elements why do you think the iron will rust and corrode where as the AL not at all. Al hould corrode more than Iron, Al is less noble metal

Why no one installs sacrifice anode on AL boats and ships ?

Disclaimer - I have a PhD in Chemistry and was the Chief Chemist of a large shipping organization

Isn't the surface of untreated aluminium naturally corroded with a layer of aluminium oxide crystal preventing further corrosion to continue below the crystal layer much unlike iron?
Disclaimer - I have NO PhD in Chemistry and was never the Chief Chemist of a large shipping organization. I am versed in youtube bumblefuckery.

 

[flintknapper]

Isn't the surface of untreated aluminium naturally corroded with a layer of aluminium oxide crystal preventing further corrosion to continue below the crystal layer much unlike iron?
Disclaimer - I have NO PhD in Chemistry and was never the Chief Chemist of a large shipping organization. I am versed in youtube bumblefuckery.

The answer is yes. It is also a very hard substance and begins to form immediately (1.5nm-2.0nm) in moist air. As you said, it has the effect of protecting the aluminum. Aluminum has a high affinity for water/moisture so in most environments its a virtual certainty it will form a layer of Aluminum Oxide. But this doesn't mean that under certain chemical/electrical conditions that it won't corrode. Aluminum and Zinc are commonly used as Anodes for just this reason.

 

[Bambusiero]

yeah, all that about aluminum oxide film forming is true - but...it is a very thin film that microscopic pinhole flaws can penetrate & form corrosion pitting in high moisture/salt/galvanic environments - so don't rely on it long term. That's why higher quality aluminum parts are anodized for a much thicker oxide barrier. if it's important, you still don't put it in contact with other metals, like flint says.

 

[NLXTACY]

Ok, it’s been 18 months and I shelved this idea for really no good reason. Distractions I guess.

Something odd came up today. Customer with an 80 comes in. Truck is immaculate. Like not normal for Southern Oregon. He’s got small pits in his thermostat housing and his radiator top tank is leaking. He just did a complete coolant overhaul four years ago (according to him). It’s just odd because of how well it’s been maintained.

He did have a bunch of accessories and wiring done to his truck a few years back, after the maintenance work. He’s noticed little electrical gremlins here and there since but nothing that he noted brought him too much concern. He thought perhaps his radio was causing feedback issues in the wiring.

Turns out he has a corroded ground by his headlight AND he didn’t have one of his block grounds tightened after the engine work. The bolt was hand threaded to start but never tightened.

Voltage in the coolant was .43v

It’s very likely all of the corrosion occurred in a very very short time because of bad grounding. His cooling system likely would still be perfect had that not occurred. But since this is the first time seeing his vehicle I can make a 100% determination.

Anyway, I think I’m gonna turn on a batch and give this guy a new drain petcock.

 

[PNWTreeOctopus]

Ok, it’s been 18 months and I shelved this idea for really no good reason. Distractions I guess.

Something odd came up today. Customer with an 80 comes in. Truck is immaculate. Like not normal for Southern Oregon. He’s got small pits in his thermostat housing and his radiator top tank is leaking. He just did a complete coolant overhaul four years ago (according to him). It’s just odd because of how well it’s been maintained.

He did have a bunch of accessories and wiring done to his truck a few years back, after the maintenance work. He’s noticed little electrical gremlins here and there since but nothing that he noted brought him too much concern. He thought perhaps his radio was causing feedback issues in the wiring.

Turns out he has a corroded ground by his headlight AND he didn’t have one of his block grounds tightened after the engine work. The bolt was hand threaded to start but never tightened.

Voltage in the coolant was .43v

It’s very likely all of the corrosion occurred in a very very short time because of bad grounding. His cooling system likely would still be perfect had that not occurred. But since this is the first time seeing his vehicle I can make a 100% determination.

Anyway, I think I’m gonna turn on a batch and give this guy a new drain petcock.

Brb, gonna go tighten all my ground connections up…

 

[NLXTACY]

Brb, gonna go tighten all my ground connections up…

Honestly it’s REALLY got me thinking.

 

[PNWTreeOctopus]

Honestly it’s REALLY got me thinking.

Oh I flew past thinking and just panicked.

 

[NLXTACY]

Oh I flew past thinking and just panicked.

Well it means that it’s not JUST about regular maintenance. Anyone can introduce the problem just by adding crap to your rig or just from doing regular maintenance stuff and not completing it all the way down to a bolt.

 

[Malleus]

Well it means that it’s not JUST about regular maintenance. Anyone can introduce the problem just by adding crap to your rig or just from doing regular maintenance stuff and not completing it all the way down to a bolt.

My 2¢ here: I've been griping about draining my radiator since I bought my first 80 in 1998. The problem, for me, is that when the petcock is removed, the radiator bathes the lower corner of the engine bay in coolant, which not only makes a mess, but has to be washed off.

Ford used to have (and may still, IDK) a petcock that would drain the radiator 90° (down into a pan under the radiator), by turning the petcock but not unscrewing it all the way. It was a two piece affair so the base screwed into the radiator, and the drain screwed into that, with a O-ring seal (or maybe just a cone seat, I never took it apart). There may have been a crimp in there somewhere, because I remember not being able to disassemble the petcock by turning the drain part. It would open, but not come completely out. (I'm doing this from memory, so I may not have all the details correct)

IIRC, it also had a nipple on it, so you could connect a hose and drain the coolant into a necked container. Made for a very clean drain.

I'd pay real moeny for an 80 series radiator petcock with a 90° drain built in it.

 

[PNWTreeOctopus]

Having just spent the better part of this winter replacing cooling system parts and vacuum lines I am absolutely the guy who would forget to tighten up the grounds correctly.

I’m with @Malleus, a less messy drain for the rad would be excellent. I’m making use of the block drain with a hose for this very reason.

@NLXTACY, looks like your R&D list has one more item….

 

[Kernal]

IME I find it difficult to get good leverage on the small "wings" of the stock radiator petcock, would it be possible to design a plug that has larger/longer wings for easier removal? And/or develop a mini-tool that slides over the wings
for more leverage to help unstick a stuck petcock when working in that cramped area??

 

[NLXTACY]

IME I find it difficult to get good leverage on the small "wings" of the stock radiator petcock, would it be possible to design a plug that has larger/longer wings for easier removal? And/or develop a mini-tool that slides over the wings
for more leverage to help unstick a stuck petcock when working in that cramped area??

It’s designed with a 10mm head so an open ended wrench fits right over

 

[PNWTreeOctopus]

IME I find it difficult to get good leverage on the small "wings" of the stock radiator petcock, would it be possible to design a plug that has larger/longer wings for easier removal? And/or develop a mini-tool that slides over the wings
for more leverage to help unstick a stuck petcock when working in that cramped area??

I’m 100% in agreement. I have a brand new radiator in right now and it’s still hard to get the wings without tools.

 

[ZetheGSD]

Yeah it felt like I was breaking my fingers on the petcock last December. A 10mm to loosen this would be a god send.

 

[Sonofaskipper]

Ok, it’s been 18 months and I shelved this idea for really no good reason. Distractions I guess.

Something odd came up today. Customer with an 80 comes in. Truck is immaculate. Like not normal for Southern Oregon. He’s got small pits in his thermostat housing and his radiator top tank is leaking. He just did a complete coolant overhaul four years ago (according to him). It’s just odd because of how well it’s been maintained.

He did have a bunch of accessories and wiring done to his truck a few years back, after the maintenance work. He’s noticed little electrical gremlins here and there since but nothing that he noted brought him too much concern. He thought perhaps his radio was causing feedback issues in the wiring.

Turns out he has a corroded ground by his headlight AND he didn’t have one of his block grounds tightened after the engine work. The bolt was hand threaded to start but never tightened.

Voltage in the coolant was .43v

It’s very likely all of the corrosion occurred in a very very short time because of bad grounding. His cooling system likely would still be perfect had that not occurred. But since this is the first time seeing his vehicle I can make a 100% determination.

Anyway, I think I’m gonna turn on a batch and give this guy a new drain petcock.

Whatchu tryna say bout Southern Oregon rigs?!

 

[NLXTACY]

Whatchu tryna say bout Southern Oregon rigs?!

They are a mess

 

[PIP]

Good idea.

I would design it completely differently though. First, I'd not do it in aluminum because it would require anodizing to hold up (preferably type 3) and anodized aluminum is an insulator. I'd make it from stainless and make it hollow. I believe what I'd do is machine from stock large enough to drill and tap the exposed end for 1/4 NPT. Have the body neck down and threaded with the ring seal to pass into the radiator. Inside the radiator I'd drill a cross hole through what is essentially a tube around 3/8" diameter. The cross hole would facilitate draining the radiator without removing the whole enchilada. In the end of this tube I would fix the zinc nugget. I'm not a super fan of the spring pin holding it in place because I've built products with small spring pins before and they are a PITA to assemble plus hard for the end user to maintain down the road. The simplest method could be adding external threads to the zinc nugget, like 1/8 NPT that screw into the open end of the stainless, but then what happens as the zinc disappears? Does it fall off and float through the engine? Maybe a better approach would be a reduced ID at the end of the stainless tube and affixing the zinc with a stainless machine screw accessed from the other end.

The device would ship with either a 1/4" pipe plug or a 1/4" petcock of some sort.

That's probably how I would do it. If you want a few thousand of them let me know. LOL.

 

[DivByZero]

The answer is yes. It is also a very hard substance and begins to form immediately (1.5nm-2.0nm) in moist air. As you said, it has the effect of protecting the aluminum. Aluminum has a high affinity for water/moisture so in most environments its a virtual certainty it will form a layer of Aluminum Oxide. But this doesn't mean that under certain chemical/electrical conditions that it won't corrode. Aluminum and Zinc are commonly used as Anodes for just this reason.

Fun fact: if you machine aluminium perfectly smooth, and keep it free of contamination (IE, fingerprints), it's perfectly reflective and never oxidises. Aluminium requires some level of surface pitting for the oxygen to "settle on" in order for oxidisation to occur. A perfectly smooth aluminium surface will not oxidise. We use machined aluminium "mirrors" inside laser scanners where I work. Lasts forever, and no refraction to mess with the deflection.

 

[Kernal]

I generally reach down from above to loosen the petcock and can barely reach it with my fingers. I was thinking of something like a socket that has a wide groove cut out side-to-side so it would fit over the wings/ears of the petcock, possibly with a short movable arm ie: so it could be snaked down from above, slide the split socket-like tool over the wings, move the attached short arm to something like 90 degrees off the axis of the tool, turn the arm/socket tool and loosen the petcock??

Or, design it with longer/wider wings/ears for more finger leverage??

I'm sure whatever Wits End comes up with it will be a well designed/built tool

Thanks

 

[PIP]

Fun fact: if you machine aluminium perfectly smooth, and keep it free of contamination (IE, fingerprints), it's perfectly reflective and never oxidises. Aluminium requires some level of surface pitting for the oxygen to "settle on" in order for oxidisation to occur. A perfectly smooth aluminium surface will not oxidise. We use machined aluminium "mirrors" inside laser scanners where I work. Lasts forever, and no refraction to mess with the deflection.

Very interesting. I'd think there would be a process involved beyond machining to get a "perfect" finish on aluminum- Like lapping. To get it to a perfect mirror finish.

One of the products I'm involved with uses mirrors for images. Those expensive little mirrors are first surface so the images aren't distorted. I will have to ask what kind of material they are made from.