Carl. I've been using your molasses dip idea to clean up rusted parts. It works great. But I bought some Aussie Cleveland 2V heads and I've been trying to get the rust cleaned out of them, especially in the water jackets.

It's taking time. Seems like our Oz friends don't use anti-freeze. The scale is pretty bad.

But I've noticed something strange. I've had the heads out for a little while because they were turning blue. At first I thought it was because they were soaking for so long that the molasses did something weird to the metal. Then I remembered hearing that the Oz stuff is high nickel and that high nickel iron turns blue when it's been cleaned.

None of the other y-block stuf that I've cleanedf turned blue, just a nice grey color of bare iron and bare steel.

Ever seen something like this?

 

Paul,

At first I thought you had been invaded by those Intel Ad guys.

Carl will know about engine parts for sure, but I can tell you that high-nickel wrought alloys plus sulphur can make some nice blue sulphates on the surface. Certain nickel-oxides are definitely a blue color depending on how thick they get. Either could be forming in the molasses mix and the oxides are tightly adhered to the metal surface. That's the primary reason nickel alloys (Stainless steel, etc.) are so corrosion resistant. The oxides that form do not allow much oxygen diffusion and they are bonded so tightly to the nickel alloy surface that they don't chip off or crack easily. They effectively keep the oxygen away from the metal once a thin layer forms.

 

George, As usual, I'm floored by the wealth of knowlede you provide.

So now I'm wondering, in light of the strong bond that the nickel makes with the surface iron, what is it going to take to get those silly heads descaled. I may just have to take it to my machinist and have him hot-tank it. Except for the scale that remains in the water jackets, the head is quite clean now.

BTW, that was a clever quip about the Blue Men. Those guys look too weird.

 

Just to be clear, Paul, the nickel-oxide is a form of corrosion that bonds strongly to the underlying alloy. In those alloys, a very, very thin corrosion product forms and then the corrosion stops because oxygen can no longer penetrate to the bare metal alloy below. The initial corrosion actually stops further corrosion!

I get the impression that these heads are not one-off versions, so I'm sure Carl and others have plenty of experience and can advise you as to what's normally used to clean them up.

 

Thanks for the clarification, George. I'm planning on leaving the blue coating on the heads before I paint them. That ought to be a pretty strong primer layer. The heads will be surfaced prior to being bolted on so that surface will be clean. I'm guessing that if I polish the ports and then let them get oxydized before use, they might actually stay cleaner, resist that carbon build-up.

I'm having a recollection that someone recommended steam furnace descaler for cleaning out water jackets in blocks and heads. I'll be checking around for that tomorrow. I have a 312 and a 223 and those Oz heads that need de-scaling.

 

Paul, Ive seen the blue before but not on heads.
You say the scale is still there but its sealed in a blue film??
Can you poke it off and flake off the scale or has it done some form of bond?

The cleaner used in hot water furnaces is Hydrochloric Acid, nasty stuff to work with without lots of care and protection. Plain old Muriatic Acid is a diluted Hydrochloric and will also dissolve the rust BUT both will also attack virgin metal aggressively so you have to be real attentive. Its not a sit and let soak for a day; you will have mush. You need a plastic container.

Also the acid needs to be neutralized. This will require first rinsing thoroughly in clean water and then immersing in a tank of warm water with baking soda dissolved in it to neutralize the acid.
The end result will flash rust in an instant so you need to oil all machined surfaces and maybe paint the exterior.

Phosphoric Acid will also dissolve rust but is much less aggressive to the base metal. This is what is used in most acid dips.

Another product is Sodium Hydroxide aka Lye. This is an alkaline as opposed to an acid and also does a nice job on rust and wont harm the base metal. I use this a lot when Im doing production work on engines since it is much faster than molasses BUT it also requires full protective gear, especially when heated to 175 F. A 275 gallon home heating oil tank cut in half works good for big items and you still get to use the legs for support.

 

There you are.

The blue is on the outside surfaces that have been cleaned by alternating washes of molasses and oven cleaner (another of your clever ideas. I found a source where I can get the good stuff for $1.00 per can. I bought a case, Hot Damn.) The outer surfaces and the ports are clean (and blue). The water jackets still have scale in them.

I've used HCl before. Nasty. I might have some Phosphoric Acid left over from some furniture refinishing. I'll give that a try. Meanwhile, the heads are going back into the molasses as soon as there's room in the barrel.

Thanks, Carl.

Oh, yeah. Almost forgot to mention. Lye will neutralize HydroChloric acid, so there's a nice way to clean that up. NaOH + HCl -> H2O and NaCl - salt water.

 

Could one of you explain to me what this molasses rust remover is? I'm always cleaning rusty stuff and would like something quicker than the sit for 4 days in straight C.L.R process. Thanks, -4speed

 

This molasses process is slower than, well, molasses. But it really works. It won't touch grease and paint but it will completely eat rust and leave a bare iron surface. It also eats brass, copper, and aluminum.

I bought a 55 gallon barrel with lid for $8.00. Then I went to the feed store and bought about 10 gallons of molasses. It was cheap. Put some water in the barrel, put the molasses in, fill the barrel about 2/3 full, and, vwa-lah, Carl's cold tank rust remover. Completely bio-degradeable, good for the evergreens (contains iron when you're done).

Put your rusty heads in and leave them for two weeks. Take them out and pressure wash them. You'll see grey iron washing off the parts, the residue of rust when the Oxygen is removed. The rust is gone. No damage from sand-blasting, no need to wire-brush or scrape, no scratch marks, looks like new.

To get the grease, carbon, and oil off, use oven cleaner.

Search this web site for the complete story.

 

Oxalic acid may be another alternative. It used to be the major ingredient in most of the cooling system flushes you could buy. Remember the ones that also had a neutralizer powder in a separate compartment of the container? Anyway, oxalic is pretty gentle on iron but is very effective at on rust and scale. Last time I bought oxalic was from the drugstore in a powdered form. It works very quickly when mixed with hot water.

 

Thanks menten, Fenders' might have to give that one a try! -4speed