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Questions on Removing rust inside bottom of block by electrolysis

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BigBlockMopar
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Re: Questions on Removing rust inside bottom of block by electrolysis

Post by BigBlockMopar »

Dave Koehler wrote: Sun Aug 04, 2019 5:23 pm I was trying to remember which detroit blocks invariably had a wire chunk floating around in there. Chrysler or Ford?
...
I've found steel wires in big-block Mopar heads a few times.
Never in the blocks.
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Re: Questions on Removing rust inside bottom of block by electrolysis

Post by engineman1642 »

electrolysis is more of a line of sight type cleaner. I have a 55 gal drum set up for it ,removes outer rust nicely but inner rust and scale not so much.I have left heads and blocks for days without any internal removal.Molasses works but it takes time sometime it takes a lot of time.
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Re: Questions on Removing rust inside bottom of block by electrolysis

Post by Kevin Johnson »

engineman1642 wrote: Mon Aug 05, 2019 8:23 am electrolysis is more of a line of sight type cleaner. I have a 55 gal drum set up for it ,removes outer rust nicely but inner rust and scale not so much.I have left heads and blocks for days without any internal removal.Molasses works but it takes time sometime it takes a lot of time.
We used to use bubblers to circulate the solution in electropolishing baths.
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Re: Questions on Removing rust inside bottom of block by electrolysis

Post by BigBlockMopar »

I’ve cleaned up radiators and carious small parts with citric acid.
Rust turns into a white powder and settles down.
Good flushing with water is needed to get it out and neutralise the acid.
Citric acid is used in soda drinks and all kinds of liquid soaps.
It also smell like a cleaning liquid when used.
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Re: Questions on Removing rust inside bottom of block by electrolysis

Post by fordified »

Electrolysis doesn't take 20 minutes to make a difference. It's more like 2 days. By the time you spend the money on getting your electrolysis rig up and running and then the cost of electricity, your probably at $100. I can pretty much guarantee you'll be disappointed in the results to boot when it comes to doing a block like that.

As someone mentioned electrolysis is directional so your anode has to be in the line of sight to where the rust is. You have to keep moving it to different places or connect dozens of them at different places to remove the rust. There are places that it won't reach.

As someone else mentioned, having a machine shop do the work is a bargain and no I don't own a machine shop. If you can spend $200 to get the block cleaned and rolled with shot then you'll be miles ahead in the long run. The block will come out looking better than new.

Spend some money and do it right.
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Re: Questions on Removing rust inside bottom of block by electrolysis

Post by Elroy »

fordified wrote: Mon Aug 05, 2019 2:41 pm As someone else mentioned, having a machine shop do the work is a bargain and no I don't own a machine shop. If you can spend $200 to get the block cleaned and rolled with shot then you'll be miles ahead in the long run. The block will come out looking better than new.
Its amazing how good a block looks when done this way, it really is. They also seem to be less resistant to future rust afterwards. I believe the shot must seal the pores of the cast iron to some degree.
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Re: Questions on Removing rust inside bottom of block by electrolysis

Post by Krooser »

I use molasses. A 40 lb bag costs $18.00 at the feed store and makes up three 55 gal drums.

Soak the block for a week....take it out, wash it and repete until it's clean enough for you.

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Re: Questions on Removing rust inside bottom of block by electrolysis

Post by Krooser »

I use molasses. A 40 lb bag costs $18.00 at the feed store and makes up three 55 gal drums. Mix with water.

Soak the block for a week....take it out, wash it and repete until it's clean enough for you.

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Re: Questions on Removing rust inside bottom of block by electrolysis

Post by Schurkey »

I've done electrolysis. Even bought a 24-volt big wheeled battery charger to speed things up.

That said...Not hugely impressed. The chunk of metal you're using to absorb the rust has to be cleaned periodically or there's no conduction, all the voltage won't flow any current and the rust removing process stops.

The process is deeply reliant on the sacrificial metal, and as soon as the process starts...the sacrificial metal goes away.
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Re: Questions on Removing rust inside bottom of block by electrolysis

Post by modok »

How molasses removes rust is quite a mystery.
I've been spilling coffee in the passenger footwell for 15 years, day after day, it's accumulated.... and you know what?
It's sticky, real sticky, but not any rust down there.

What the heck?
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Re: Questions on Removing rust inside bottom of block by electrolysis

Post by 4vpc »

peejay wrote: Sun Aug 04, 2019 6:11 pm
4vpc wrote: Sun Aug 04, 2019 1:31 pm Anhydrous citric acid granules mixed with water is the cheapest easiest way I found of removing corrosion from anything ferrous. It's cheap (Ebay) and safe to use. De-grease and blast your block clean inside and out, use your coathanger again to get the loose and thick stuff out then either throw it in a bath of the stuff, or just fill it up and leave it.
Interesting! Will that stuff eat galvanizing like hydrochloric will?
Probably, I know it cleans off zinc plate. I've been using it for years, if it's used cold it's slow, if you heat it it does the job much faster.
To quash some incorrect theories posted above:

You will have found its common use and name so you can be assured exactly how safe it is?

It does not eat into the metal if there is no rust there unless you leave it in for a silly amount of time (like a month or so) then it starts to attack it. If you don't want to take the risk then simply grease the parts you are bothered about.

The part does not rust when you bring it out, if you let the stuff dry on it leaves a brown film over it which stops passive corrosion (from humidity etc).
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Re: Questions on Removing rust inside bottom of block by electrolysis

Post by 4vpc »

modok wrote: Sun Aug 04, 2019 11:53 pm I've seen SO much damage from acid washing or shot blasting or bead blasting, it's not worth it. to do it right you need to mask off ALL surfaces and bolt holes and areas you can't clean, and then clean it afterwards anyway. IMo most of the time it would be, in retrospect, faster to just wire brush it.
Rust isn't really a bad contaminant, it's not great, but it's not too bad, It's more of a polishing agent than an abrasive.
glass beads, steel shot......that's DEATH to bearings.

Of course, jut MY opinion. I'm sure all methods work great when done right, I just see it go wrong so many times......
It depends on the type of acid, who is using it and how.
I remember a customer bringing in a block, I eyed it suspiciously. "I've had it shot blasted!" he says, my heart sinks. "They've cleaned it all out though" he says, dumping it on the floor. I turn it over noting the small piles of shot on the floor. Turns out he'd previously kept it in his garden for 10yrs, I pointed out a crack in it caused by it being frozen and sent him on his way.

I would never use abrasive media on blocks, always liquid, but do wonder what pieces of broken up glass bead would do if still in there. I don't think it would damage anything but soft bearing material and aluminium. Anything iron or steel is harder than the glass itself, I won't be testing it though...
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Re: Questions on Removing rust inside bottom of block by electrolysis

Post by modok »

Oh....you'd be amazed.
I've seen aluminum block that was bead blasted EAT it's lifters. I mean EAT. 1/8 clearance, barely made it 500 miles.

All in pressure control and distance, to get in the zone where it's working, but not embedding in the material, not rocket science but....easy to mess up.
Wet blasting should be a lot better, but complex rig, looks like a real PITA

Something like a WET shot blaster might work great, but.....still would not clean out the water jackets where you can't see.
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Re: Questions on Removing rust inside bottom of block by electrolysis

Post by Kevin Johnson »

I mentioned previously that while electropolishing, bubblers can be used to agitate the solution. This helps to reduce the tendency towards line-of-sight migration of ions through the solution.

Below is a discussion of different types of bubblers/circulation used in electroplating. This has application in electrolytic removal of rust as well. Good luck.

https://forum.caswellplating.com/forum/ ... r-aeration
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Re: Questions on Removing rust inside bottom of block by electrolysis

Post by Schurkey »

exhaustgases wrote: Tue Aug 06, 2019 3:18 am
Schurkey wrote: Tue Aug 06, 2019 1:15 am I've done electrolysis. Even bought a 24-volt big wheeled battery charger to speed things up.

That said...Not hugely impressed. The chunk of metal you're using to absorb the rust has to be cleaned periodically or there's no conduction, all the voltage won't flow any current and the rust removing process stops.

The process is deeply reliant on the sacrificial metal, and as soon as the process starts...the sacrificial metal goes away.
The block would be negative and the other metal is positive, ??? That makes the block the sacrificial metal???? And why the rust would leave it and be attracted to the positive material.
My experiments with electrolysis were more than a decade ago. I've LONG since forgotten which way the battery charger leads are connected. I deliberately did not specify lead position in my previous post.
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