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Questions on Removing rust inside bottom of block by electrolysis

General engine tech -- Drag Racing to Circle Track

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rockosocko
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Questions on Removing rust inside bottom of block by electrolysis

Post by rockosocko »

I'm wanting to know if any of you guys have done or tried to dump a whole engine block in a 'vat' to remove rust by using electrolysis?
This 283 that I'm going to be freshening up looks like it's NEVER been hot tanked for rust after pulling the freeze plugs out and looking down in there. (and NO, can't afford $150-200 for a 'shop' to do it around here.. It's OUTRAGEOUS what some shops charge in the Memphis area JUST TO VAT 1-block..!)
I had a numbers matching '72 Monte Carlo that I rebuilt the motor on and at the time using my pressure washer and coat hanger to get down in between the cyls at the bottom of the block, and got out about 4 FULL cups of rust/crap! And that was AFTER having a shop 'hot tank' it.. go figure. Probably just let it soak for a few hours.
I don't want to let this go, and always be in my mind of "I should-a"..

I have a plastic 55gal drum, some stainless flashing from a chimney for the Anode that can be expanded fully around the inside of drum.

Thanks for your time and input.
E
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Re: Questions on Removing rust inside bottom of block by electrolysis

Post by Walter R. Malik »

rockosocko wrote: Sun Aug 04, 2019 12:16 pm I'm wanting to know if any of you guys have done or tried to dump a whole engine block in a 'vat' to remove rust by using electrolysis?
This 283 that I'm going to be freshening up looks like it's NEVER been hot tanked for rust after pulling the freeze plugs out and looking down in there. (and NO, can't afford $150-200 for a 'shop' to do it around here.. It's OUTRAGEOUS what some shops charge in the Memphis area JUST TO VAT 1-block..!)
I had a numbers matching '72 Monte Carlo that I rebuilt the motor on and at the time using my pressure washer and coat hanger to get down in between the cyls at the bottom of the block, and got out about 4 FULL cups of rust/crap! And that was AFTER having a shop 'hot tank' it.. go figure. Probably just let it soak for a few hours.
I don't want to let this go, and always be in my mind of "I should-a"..

I have a plastic 55gal drum, some stainless flashing from a chimney for the Anode that can be expanded fully around the inside of drum.

Thanks for your time and input.
E
Do it yourself with a rigged 55 gallon plastic drum and keep track of the electric power being used ... it will surprise you.
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Re: Questions on Removing rust inside bottom of block by electrolysis

Post by 4vpc »

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

Post by BillK »

rockosocko wrote: Sun Aug 04, 2019 12:16 pm can't afford $150-200 for a 'shop' to do it around here.. It's OUTRAGEOUS what some shops charge
Some of you guys should actually have to pay the bills that a machine shop has. Then you might understand why we have to charge what we charge. It costs me over $600 every few months to have my Jet Spray washer pumped out and it isn't even caustic like an old school hot tank (what you are calling a vat) I cant imagine what that costs. Not to mention the employee costs etc etc. I have an oven and shot blaster for most cast iron stuff and it uses a crap load of gas and electricity.

If you want to try it I know some guys that use muriatic acid from Home Depot and claim it works ok. Put the block an a stand, fill the water jackets with acid. Let it sit however long then drain it out and rinse it. Then do the other side. Then you have to neutralize it. Then you have to get rid of the used acid ? By the time you are done you will probably think the $200 is a bargain :)
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Re: Questions on Removing rust inside bottom of block by electrolysis

Post by Kevin Johnson »

Years back I had a visit from the county inspector. Very first thing he asked about was solvents for cleaning parts. You will need receipts from the legal hazardous waste company. Good thing I was not using any acids.

I thought people were using molasses?

About 50 years ago my Dad brought home some citric acid from the lab and cleaned all the rust off of my bicycle. Works great, I agree. All those active sites will come back pronto if you don't use a good sealant/protectant of some sort immediately after.
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Re: Questions on Removing rust inside bottom of block by electrolysis

Post by Dave Koehler »

Yeah, those blocks from the mid 70s on back could be really clogged up.
Some we would soak and later jet spray clean, remove, rinse the water jackets from different directions.
Then let it set for a few days to totally dry out. Some of the thicker accumulated stuff would then break loose.
Then back in the tank or jet cleaner.
Kind of a rinse and repeat until it was ll all out.

These days a 3500 psi Harbor freight pressure washer might do the trick to blast that stuff loose.

Oh, and people also complained way back when it was an outrageous 50 bucks.
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Re: Questions on Removing rust inside bottom of block by electrolysis

Post by PackardV8 »

rockosocko wrote: Sun Aug 04, 2019 12:16 pmI had a numbers matching '72 Monte Carlo that I rebuilt the motor on and at the time using my pressure washer and coat hanger to get down in between the cyls at the bottom of the block, and got out about 4 FULL cups of rust/crap! d that was AFTER having a shop 'hot tank' it.. go figure. Probably just let it soak for a few hours.

Thanks for your time and input.
E
Yeah, those blocks from the mid 70s on back could be really clogged up.
Some we would soak and later jet spray clean, remove, rinse the water jackets from different directions.
Then let it set for a few days to totally dry out. Some of the thicker accumulated stuff would then break loose.
Then back in the tank or jet cleaner.
Kind of a rinse and repeat until it was ll all out.
X2, Dave. Most of the foundries were not particularly good at getting all the casting sand and core wires out of blocks. Given cores are expected to withstand molten iron, the residue can really be cooked in there. When we're working on the older engines, sometimes a 1/4" round rod and a ball pein hammer is the best tool for loosening that fifty years of crap in the bottom corners of the water jackets. One Packard V8 block had been treated to some really nasty radiator stop leak. It took two days of baking, shot blasting, pressure washing and hammer and chisel work to get that one clean enough to begin machine work.
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Re: Questions on Removing rust inside bottom of block by electrolysis

Post by Dave Koehler »

I was trying to remember which detroit blocks invariably had a wire chunk floating around in there. Chrysler or Ford?

Did their process get better?
I recall it stopped being an issue with mid 70s and up.
I always assumed the antifreeze improved and people got used to running it year round.
Way back people only bought the expensive antifreeze for wintertime and ran straight water in the summer. Sounds silly but there it is.

Drag racers run straight water for the most part. I have seen and can guarantee that straight water will eat a pin hole in the brand new installed steel core/freeze/frost plugs in one summer season. It will also create that rust sludge at the bottom. That's why brass plugs are available. :D
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Re: Questions on Removing rust inside bottom of block by electrolysis

Post by Joe-71 »

What I found to work amazingly easy was to put the block on an engine stand, move it outside where you can turn it over part way, and use my portable sand blaster with 175 PSI, and play sand from Lowes, which is finer grain than regular blasting sand. There are usually four grades of sand for the sand blaster, but the Lowes' playground sand just works better because it is so fine, and it doesn't damage the liners. Tilt the engine over, and let the crud drop out, and repeat if necessary. All the scale will be gone, no need to neutralize afterwards. Use the high pressure washer to remove any grit, and it is ready for core plugs. Joe-JDC
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Re: Questions on Removing rust inside bottom of block by electrolysis

Post by peejay »

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

Post by 77cruiser »

Just cleaned an old tractor radiator of rust about a month ago with CLR. Worked pretty good. Neutralized with Purple Power.
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Re: Questions on Removing rust inside bottom of block by electrolysis

Post by peejay »

exhaustgases wrote: Sun Aug 04, 2019 7:08 pm
BillK wrote: Sun Aug 04, 2019 2:09 pm I have an oven and shot blaster for most cast iron stuff and it uses a crap load of gas and electricity.
And what temperature is used? How come a simple over heat can warp heads and cleaning with 700 degree's F doesn't need to be completely remachined from stress relieve and massive distortion? Really curious.
It's not the heat, it's how it is applied. Overheating an engine adds the heat to the exhaust ports and combustion chambers first, and it spreads from there. Usually not even that evenly, as you can have areas with film boiling running super hot and other areas that still have coolant contact running relatively cool. Having a few hundred PSI randomly pushing on the chambers and the valvetrain waggling the metal this way and that also doesn't help things. An oven will heat everything up everywhere at the same time, and there's no forces pushing on things.

That said, I've heard that a lot of times you do need to remachine everything after oven blasting.
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Re: Questions on Removing rust inside bottom of block by electrolysis

Post by PackardV8 »

exhaustgases wrote: Sun Aug 04, 2019 7:08 pm
BillK wrote: Sun Aug 04, 2019 2:09 pm I have an oven and shot blaster for most cast iron stuff and it uses a crap load of gas and electricity.
And what temperature is used? How come a simple over heat can warp heads and cleaning with 700 degree's F doesn't need to be completely remachined from stress relieve and massive distortion? Really curious.
There's no curious about it. Most everyone we know assumes a head or block coming out of an oven will be surfaced, have the seats and guides machined. Look at any large rebuilder and there are dozens of heads and blocks coming out of their ovens early every morning and are going out the door as ready to run engines that evening.
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Re: Questions on Removing rust inside bottom of block by electrolysis

Post by modok »

Joe-71 wrote: Sun Aug 04, 2019 5:32 pm What I found to work amazingly easy was to put the block on an engine stand, move it outside where you can turn it over part way, and use my portable sand blaster with 175 PSI, and play sand from Lowes, which is finer grain than regular blasting sand. There are usually four grades of sand for the sand blaster, but the Lowes' playground sand just works better because it is so fine, and it doesn't damage the liners. Tilt the engine over, and let the crud drop out, and repeat if necessary. All the scale will be gone, no need to neutralize afterwards. Use the high pressure washer to remove any grit, and it is ready for core plugs. Joe-JDC
There you go. Smartest guy here!
"Removing rust" with acid or electrolysis.....weakens the part, it's OK for decorative parts, not good for tools and engines.
Work smarter not harder.

Baking the block then re-machining the whole thing....what is this, ....is that how they do it in Russia? Making work for yourself. :P
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Re: Questions on Removing rust inside bottom of block by electrolysis

Post by modok »

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......
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