Electrolytic engine cleaning

[Richter12x2]

I ran into an issue getting the GT6 head and engine block clean because of all the nooks and crannies, particularly on the early '67 head with the external pushrod guides. Finally, I ran across a thread on truckforum.org about how one guy used electrolysis to save a rusted engine block that his builder had told him was junk.

The idea is that you submerge the piece of metal in water, add a salt to use as electrolyte (baking soda in this case) and add a ready supply of current (from a 10 amp battery charger) and as the ions move from the the negative portion (the engine block or head) to the positive (the anode that you have managed to find) the rust will move away also.

I picked up a plastic 55 gallon drum for $10 and 20' of copper tubing ($17 from Lowes) and got cracking. The formula I used was roughly 2 teaspoons of baking soda per gallon of water, but your mileage may vary. Adding more increases the current through the water. I started with 1 teaspoon and on the 10 amp setting, my gauge showed the battery charger was only putting out 4 amps. After adding another teaspoon, that cranked up to just over 9 amps, which I figured was good enough to cook overnight.

Here's some pictures of the progress:

Head in the barrel

Process started, at 1 minute, can already see bubbles beginning to churn off the block.

After about 1.5 hours

After 4 hours it was bedtime and I was a little leary about letting it go all night, so I pulled it out and checked it, and it was cleaner, but still had a ways to go. Since this was a 'spare' head, I figured I'd see what happened. I cleaned the copper tubing and stuck it back in.

This morning, I pulled the head out and gave it a quick scrub with a scotchbrite pad. Paint and a gasket that I couldn't even see under the oil and sludge came off with barely more than a touch of the scraper.

Because of the electrolysis, surface rust comes back in minutes, but can be scrubbed away with a toothbrush to get ready for paint:

These are the little buggers that made it such a pain to clean.

I just shot some paint on to keep it from rusting over again, to see how it sat and make sure it didn't lift. When I do the head we plan to go on the car, we're going to take a little more time for prep, but overall I'd call this a success!

 

[hilsideser]

I tried it a couple of years back after finding a post on a tractor site. That guy used Arm & Hammer Laundry Soda. Had a heck of a time finding it, but recently saw it at our local grocery.

(my '71 has a block # KD9492 E with the external push rod tubes, too. It had been recently rebuilt before I got it...)

 

[tdskip]

Regular baking soda works well too actually.

Nice to be able to plot something in there and come back when everything if off it eh?

 

[Gliderman8]

Ditto on everything you said!
I made the same setup when I restored my car. Anything that was rusted or need the paint strip spent time in the tank.
Be careful about leaving it on in a closed area overnight.
I still use mine for lots of other projects.

 

[John_Mc]

Be careful about leaving it on in a closed area overnight.

Forgive my ignorance: What are the risks? Do you end up producing explosive hydrogen gas, or some other noxious fume? What are the risks to the block of leaving it in too long?

 

[Richter12x2]

If you use stainless as your cathode, it works really well but releases trace amounts of something carcinogenic from the chromium. Same reason you're not allowed to chrome plate things at home. :laugh: (Although as I was setting this up I was thinking "All you'd have to do is reverse the polarity and fill the barrels with your copper, nickel and chromium baths." Barrels are cheap. :laugh: Cheaper than the heavy fines and the toxic waste disposal fees at least.

And even though I did it in the garage overnight, I started off by opening the garage door as I went in. I don't think there's anything in there that'll get ya, but better safe than sorry. Lord knows I've ended up on the wrong end of whatever's in spraypaint and cleaning agents enough, I don't want to spend my days on a respirator fighting to breathe.

Oh, actually I think it does release hydrogen, too. But appparently just about enough to launch an empty coke bottle 20 feet in the air or so.

For cast iron, there's not much risk because it changes very slowly. If you left aluminum or another soft metal in there long enough, you'd come back to a bucket with only water in it, from what I've heard. They recommend against submerging aluminum at all.

 

[Richter12x2]

That guy used Arm & Hammer Laundry Soda. Had a heck of a time finding it, but recently saw it at our local grocery.

I saw that recommended too, I went after it tonight because I thought "How cool, I can finally get rid of that oil smell in the garage AND clean my engine!" :laugh: When I compared the price lb for lb, the baking soda was about half the price though, so I couldn't bring myself to try it when the baking soda worked well enough.

As an experiment, when the amps were sitting at about 4, I dropped a handful of sea salt in, too, probably no more than a couple of tablespoons into 40+ gallons of water, and it shot up about .6 amps within a few seconds. Sea salt is quite a bit more expensive and quite a bit more corrosive though, so I don't know if I'd trust a bath of salt exclusively without some careful testing. :laugh:

 

[angelfj1]

Actually what you add to the water is not critical. All you need is to produce an electrolyte, which allows the solution to conduct electrical current. Just don't use strong acids. In fact I have used a solution of water and vinegar. It's the current that does the cleaning.

<span style="font-weight: bold">The only other critical factor is polarity. The object being cleaned, to the negative.</span>

 

[Gliderman8]

Be careful about leaving it on in a closed area overnight.

Forgive my ignorance: What are the risks? Do you end up producing explosive hydrogen gas, or some other noxious fume? What are the risks to the block of leaving it in too long?

I'm no chemist, but I do think hydrogen off gas is what's produced. Thought I remembered reading that in the article that I built mine from. I would think it is just small amounts, but better safe than... well you know!

 

[Richter12x2]

Got the block we're going to use dipped, scrubbed and painted today, Niki has more pictures probably to follow of the process - I snapped a few of the final result

 

[ekamm]

What kind of paint are you using on the outside of the block?

 

[Richter12x2]

The silver in the pictures is POR20, a high heat enamel by the people who do POR15. The plan is to topcoat it in red with the POR Engine Enamel. We've got the first coat of red on now and it's not coating nearly as well as the POR20 did, it's looking like another coat or two to get it to look good.