I can't locate a shop in Boise that has a Redi-Strip system to get the scale out of my engine blocks, so I'm making my own 'redneck hot tank' - a 55 gallon drum with a turkey fryer burner underneath to heat it. I'll be buying some Red Devil lye (NaOH) to put in the water, but I was wondering if I should add any other chemicals to the mix.

Anybody have any suggestions?

 

Well, I dont know how well this would work, but you might try Castrol Super Clean. It's mostly lye in the first place anyway. It seems to degrease stuff very well when cold, so when heated up it should work great. I've never tried it heated up, but I think it would work.

 

A scoop of oxy clean actually helped the most when I was giving my cylinder heads thier preliminary scrubbing in the utility sink.

Just out of curiosity, how are you going to dispose of all of that lye and water once you are done? Is it safe to just dump on the ground?

 

I'll pour some chlorine bleach in there to neutralize the caustic. I'll also dilute it a lot. I had pulled all the bearings out of the block so I don't expect that there's any lead or other heavy metals to worry about, just iron. Iron is good for the environment.

Previously, when I soaked some parts in molassas, I poured the used solvent onto my lawn. No harm done there, the grass is still quite green.

 

I think you want to add some acid to neutralize the 'base' lye. Essentially, lye is like super strong baking soda, and you know what happens when you add baking soda to an acid covered battery. So, if you take a sample of your soup, and add some vinegar (weak acid) and the result it neutral, you know you are on the right track to make a neutral (acid - base) solution. I don't think bleach will do what you want.
tom

 

I really don't know how to tell you how bad this idea is...

There are safe ways to do things. Check out a large city near you for someone with the proper equipment.

 

If it's rust and scale you're trying to remove rather than grease, why not use the electrolytic process? Much safer, and you can pour the by-product right on the lawn or anywhere else you want fertilized:

http://www.stovebolt.com/techtips/ru..._derusting.htm

http://myweb.tiscali.co.uk/andyspatch/rust.htm

I've done this, and while slow, it does work. Any grease or slime on the block can easily be removed at the do-it-yourself car wash.

(If you use the Castrol Superclean, be sure to wear rubber gloves. That stuff will dry out your hands big-time!)

 

Regarding what to do with the leftover lye, since it's Sodium Hydroxide, I was intending to neutralize it with Chlorine either by using bleach or HydroChloric acid. Chlorine combines with Sodium to make salt, as in table salt and sea salt.
But I've got other things that need degreasing, so I'll be using it again.

Regarding rust removal, I got a plactic barrel today with the intention of using it for the electrolysis method. It's too small for the block, but it's perfect for heads, intakes, bellhousings, etc.

I can get nice steel drums, but I'm afraid they won't work right in an electrolysis setup.

 

Nope, gotta use plastic or something non-conductive for that. But you could use metal if you put a liner in it, like a piece of an old pool or waterbed liner or some other heavy-duty plastic sheeting.

 

Dumping the iron parts in a tank filled with water and citrous acid works great if you let it soak for a few days.

 

I've tried using molassas, it does a good job on surface rust, but I'm trying to get at scale in the water jackets.

 

Well the bottle of Castrol Super Clean says biodegradable on it, maybe that's an indication? It does kill grass though. Works great on driveways.

 

You might want to try muriatic acid. Let soak overnight.

 

I've heard that the problem with HCl is something called Hydrogen Embrittlement. I'll have to google that to see what exactly that means, but I imagine that it has to do with the breaking of the Iron bonds by the infusion of Hydrogen.

 

Hydrogen embrittlement is common in petroleum pieplines that come into contact with H2S.

Any metalurgical engineers out there that can explain it to us?