Hello, I want to share a simple chemical process I just used recently for the first time to remove rust from a flathead Ford block. The process is called "chelation" (key-lay-shun), this process uses readily available materials and used correctly it is safe for you and your parts. These materials are available on Amazon and other sources, distilled water, tetrasodiumEDTA, citric acid and you will need some PH test strips. The ratio of tetrasodiumEDTA to water is important but not critical. So, let's begin, to 12 gallons of DISTILLED water add 5 lbs. of tetrasodiumEDTA. Stir/agitate until all solids are dissolved, to that solution add approximately 5 1/2 lbs. of citric acid. Only add enough citric acid to bring the solution to 6.5 PH. The flathead Ford block was left in the container for about 36 hours, when removed from the solution the surface of the block was dis-colored with a reddish brown residue that was easily washed off with a power washer to reveal a perfectly clean surface. WD-40 was applied after the block was dry.
I’m a big fan of reverse electrolysis but I’m really liking this method! Was the block completely de-greased before submerging?
Great. Thanks for sharing. We've often discussed the benefits of citric acid. Lots of threads about rust removal. But your explanation was more detailed than any I've seen. That's appreciated. Also, this is the first I've heard of using tetrasodium EDTA along with the citric acid. And I don't think that I'd heard of going to the trouble of using distilled water. Means a little more time effort and cost, but I imagine there's a good reason for it. The proof's in the pudding. Your engine block looks real good. One thing. We've also heard that using this method might not be the best thing for machined surfaces. Please do us all a favor and closely inspect your machined surfaces to see if you can determine if any actual metal has been removed. Can you still see the cross hatch in the cylinders if there was any? Can you measure the lifter bores to see if they're oversized now? Anything at all now or in the near future that might tell us that using this procedure might not be good for this purpose. Thanks. Good luck with everything.
Some details that I did not include in my initial post, the part needs to be free of oil and grease, and the part needs to be COMPLETELY submerged in the solution. This chemical reaction will not affect the parent metal. The solution has a PH of 6.5, that is considered neutral, not acidic, non alkaline. This is similar to Evapo-rust but a lot cheaper, I think I spent about $135.00 total. I used the same process on the crank. The subject block had been baked and boiled about 15 years ago and sat in my garage and got rusty, when I pressure washed the water passages the amount of crud that came out was unbelievable. Any more questions, ask away! Tom
It looks like all of the machined surfaces are now etched(rough). This is why I won't use any acid on machined cast iron. Does the EDTA 4na work without adding the acid?
Im not knocking your process as it obviously works well. Ive had the same results using tap water, less citric acid and no other ingredients. Tom, have you ever tried just the CA soak and rinse by itself ? @hotcoupe
Chelation is how Evaporust works. The thing about using citric acid is it eats away the metal, in addition to the rust. If you are careful about how long you let the rusty part soak it's okay, but chelation just removes the rust and doesn't harm the metal.
Initially, I was encouraged to see this thread, as I thought it would be a breakthrough in rust removal. I have also been trying to figure out how to get a direct replacement for Evaporust at a lower price. Quite frankly, I have had no success. A quick visit to obtain the definition of Chelation from Wikipedia will show you why this is : "Chelation is a type of bonding of ions and molecules to metal ions. It involves the formation or presence of two or more separate coordinate bonds between a polydentate (multiple bonded) ligand and a single central metal atom. These ligands are called chelants, chelators, chelating agents, or sequestering agents." Not having a good basis in chemistry, this information was too obscure to help me out at all. As I said, I was initially encouraged, but the last couple of posts and a quick look at enlarged versions of the OP's pictures have caused me to doubt my initial impression. Without "before" pictures to compare to, a close inspection of the enlarged photos does seem to show etching as mentioned above. This etching is typical of surface damage done by exposing a machined surface to acid for too long a time. Several years ago, there was a thread on here by someone who had left an engine block in a Molasses solution (also a mild acid) and ruined it. The OP himself says that the pH of the solution he is using is 6.5, which is acidic, though only slightly. When I have a chance, it would be interesting to see what the pH of fresh Evaporust is. All of this being said, I will say that I am quite impressed by the results achieved by the OP, and will probably use it myself where critical machined surfaces are not involved. Whether he has found a replacement for the admittedly expensive Evaporust is in my opinion, is still in doubt in my opinion.
Good stuff, I know and old school engine builder that used transmission fluid to coat his parts if they are not used right away , WD40 has some water formulated in its make up
The scale has values ranging from zero (the most acidic) to 14 (the most basic). As you can see from the pH scale above, pure water has a pH value of 7. This value is considered neutral—neither acidic or basic. Normal, clean rain has a pH value of between 5.0 and 5.5, which is slightly acidic. Tom
Just a thought - why not coat any machined surfaces with a film of grease before submerging in the bath? Wouldn't this prevent any possible etching on those surfaces?
I don't see any significant etching on those parts, I do see what appears to be some damage that is due to rust that was there prior to this process. But those sealing surfaces will be fine with a quick cleaning with some emery cloth. Same with the crank journals, a quick polish with some fine emery or crocus cloth and they should polish up nicely. But I agree, it would be good to see some before shots of the same parts.
Fifteen years ago I had the block boiled out and so the shake and bake procedure, the block sat in my garage and rusted. After pulling the block out of the solution I washed it with a power washer and the crud that came out of the water jackets was incredible. Included in the mess that came out of the water jackets were MANY pieces of what looked like rust colored sand, I could easily crumble the pieces. Later today I'll polish a crank journal with a piece of scotch brite and post images
Yes... rust damage, not etching. Looks to me there are before pictures. Shows the rust. As you say, gasket surfaces aren't as critical. Metal to metal machined surfaces are. I was going to say that this is exactly the thing I would be most concerned about as far as machines surfaces and using this method. Any machined surface that has been rusted and then had the rust removed, has lost some of its metal that had been converted to iron oxide. I think that if metal to metal machined surfaces aren't rusted at all, it might not be a problem. Unless maybe you leave it in there forever.
Best not to let rust get inside the engines in the first place. Don't be taking them apart if you don't have to. Take steps to store them well. Grease 'em up and put 'em in plastic bags. Not talking down to anybody. I ruined a perfectly good engine one time by disassembling it and not storing it well. Rust.
Not sure you can accurately call your process "chelation", since you are using acid. But test away. I can tell you from personal experience that acid WILL attack machined cast over time. I ruined a set of EAB flatty heads leaving them in acid for a few days. They were so soft you could scrape the metal off with your fingernail.... Acid also etches steel, leaves a nice sandblasted texture that primer sticks to nicely.
Again, the ph of the solution is 6.5 that is considered NEUTRAL. 0-6 is considered acid, 8-14 is considered alkaline. 6-8 is considered neutral. Tom
It seems to me there may be a little misunderstanding by some about citric acid. Yes, it's an acid but if you've ever had any citrus fruit, ie oranges, lemons, limes, or had a drink of Tang or country time lemonade, you are taking into your body citric acid. Maybe I'm way over thinking this but it seems people are so concerned about the effects of "acid" that they are overlooking the fact that citric acid is actually not a bad thing. The same can be said about acetic acid, commonly known as vinegar. Larry
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