Evaporust for Stuck pistons?

Has anyone had success using Evaporust in an engine with pistons stuck? I have a Detroit Diesel that I can't get to turn over and was considering pulling the head and using some to get the pistons loose, if that is indeed the problem. Think that it would penetrate between the rings and cylinder wall? Obviously would be changing oil afterwards, so wouldn't worry about contamination that way.

Several YouTube channels I watch are using it profusely in tool restoration, so figured it would be worth a shot in this application.

Seems like someone asked this just the other day...

I've never tried it, and probably never will, but my concern is it works by removing oxidized metal, which means it would further etch into the cylinder walls and the sealing surfaces of the rings.

It is a mild acid, introducing acid to an engine is never good. Problem is, even if it did break the engine loose, if for some reason the engine didn't get started and run, the acid would be trapped in and around the pistons and would continue to corrode the surfaces.

If an engine has had liquid water siting in a cylinder long enough to stick the engine, chances are the rings will not be free enough to seal. The cylinder will soon carbon up, leak by the rings, overheat, and do further damage.

If soaking in light oil doesn't do it, chances are it will need to come apart.

Might not be the pistons. Pull the rear
covers and attempt to wiggle each
component. Last one I had stuck was the
blower.

My thoughts are if the cylinder is that rusted, in the end the cylinders will have to have sleeves put in. If that is done it will need new pistons too. Might as well drive the pistons out with a block of wood and a hammer.

I use Evapo-rust on a lot of stuff. Steve, it's non-acid. It works on surfaces but it's not a penetrant so net useful for stuck pistons. If you get them out it will do a good job cleaning them up after a good wire brushing.

Evaporust is a chelating agent and is slightly basic not acidic. It will chelate and remove mostly iron ions but will also affect some other divalent metal ions such as magnesium and calcium. It does not clean so you have to clean the piston top with brake cleaner or what ever you want to remove most of any oil or contaminant that is present.

I have used it many times with only one failure. I just fill the cylinder a few inches over the piston top and check every once in a while to see if the piston is free. It may need to soak for a few weeks. The evaporust will soak to the rings and beyond. It will NOT affect non-rusty steel or iron. I also use it to clean carbs and electronic parts such as variable air capacitors.

The active ingredient is Ethylenediaminetetraacetic acid. commonly called EDTA. It is a very mild acid and is used medicinally to neutralize heavy metal poisons. It will penetrate quickly into rust and slowly into steel or iron, but would be slowed or stopped by oil.

There are hundreds of chelating agents, molasses, Roundup, EDTA, and many industrial chelating agents used for lime scale removal. Nothing about Evaporust points to it being EDTA. It is likely a mix of several chemicals including one of the many industrial chelating agents.

EDTA is not used as pure EDTA since it is poorly soluble in water. It is used as an acetate salt, typically the disodium salt. A salt, (disodium EDTA), of a weak acid, ( pure EDTA), is a weak base. What is typically called EDTA by the layperson is really disodium EDTA and is a weak basic buffer.

I have several jars of disodium EDTA and it will not work or function like evaporust.

Molasses is a weak chelating agent which may explain some of the rust removing properties of a molasses and water solution.

Roundup is also a chelating agent which is the reason for the white slime that forms in Roundup when mixed with hard water.

Evaporust worked for me for freeing rusted pistons or other parts better than a penetrating oil soak. It may be worth a try. I like the fact that evaporust will remove the rust so the piston is not being moved and dragged through the rust as it would be with penetrating oil.

(quoted from post at 06:18:33 07/17/19)
There are hundreds of chelating agents, molasses, Roundup, EDTA, and many industrial chelating agents used for lime scale removal. Nothing about Evaporust points to it being EDTA. It is likely a mix of several chemicals including one of the many industrial chelating agents.

EDTA is not used as pure EDTA since it is poorly soluble in water. It is used as an acetate salt, typically the disodium salt. A salt, (disodium EDTA), of a weak acid, ( pure EDTA), is a weak base. What is typically called EDTA by the layperson is really disodium EDTA and is a weak basic buffer.

I have several jars of disodium EDTA and it will not work or function like evaporust.

Molasses is a weak chelating agent which may explain some of the rust removing properties of a molasses and water solution.

Roundup is also a chelating agent which is the reason for the white slime that forms in Roundup when mixed with hard water.

Evaporust worked for me for freeing rusted pistons or other parts better than a penetrating oil soak. It may be worth a try. I like the fact that evaporust will remove the rust so the piston is not being moved and dragged through the rust as it would be with penetrating oil.

Click to expand...

Electro, it is not a big deal either way, but there is a LOT that points to Evaporust being EDTA. The formula is proprietary and apparently well guarded, but there are literally hundreds of posts on many different forums over a number of years about the similarity in performance. Where I work we get it in powder form and it goes into a number of different products.

Showcrop,
For me it is really more for academic interest as to what is in evaporust. I have found nothing on what is actually in evaporust. I did find a lot of conjecture from many keyboard experts but nothing with any scientific explanation associated with their "expert" opinions. I have found that these experts say with all the assurance they can muster that it is composed of phosphoric acid alone, citric acid alone, oxalic acid alone, EDTA alone, and all of the above combined. None of which makes sense to me. Lots of conjecture but no real explanation to back up their claims.

EDTA will chelate aluminum, evaporust does not. EDTA works to chelate as a basic solution salt. It has very little solubility in an acid solution. Evaporust is not a base, it is either neutral or slightly acidic although my litmus paper testing has always shown it to be neutral. EDTA will not have much effect in a neutral solution, it will have some effect, but not much.


If there are truly LOTS of reasons that point to evaporust using EDTA as the chelating agent then I would be interested in the chemistry that supports that reasoning or links to a real explanation, not just the opinions of some keyboard experts.

Unlike the keyboard experts rambling on potentially dangerous topics such as medicine or electrical advice, nobody is going to die from a wrong opinion as to what is in evaporust but for me it is truly just for academic interest. However, accurate information is useful but the ramblings of all those keyboard experts out there is not at all useful. And no Showcrop, this is not directed at you, I appreciate your help and comments, but towards all those keyboard experts in the internet land (and there are a few on this site).

What was stuck on the blower? I've heard a couple of different places that they can be an issue. Is it a matter of oxidation between the case and the rotors?