Block cleaning

[Chris Haynes]

I am going to R&R my head to add a higher compression unit. So today I disconnected the radiator hoses. Plugged the inlet hose on the side of the block then poured in a gallon of Muriatic acid. I let it sit for a few hours then removed the plug and let it drain. Stuck the hose in the outlet on the head and flushed out huge chunks of rust and grime. A flashlight in the block shows clean bare metal. Tomorrow I will switch the head and fill it with coolant and anti rust. Hopefully it will run cooler.
I guess it would be a good time to back flush the radiator too.

[Tom Wesenberg]

I would never pour in muriatic acid. It will continue to eat the metal unless it's very well neutralized. Even the fumes from muriatic acid will quickly rust metal for several feet around. I'd pour in Evaporust and let it set for a few days.

[daveymc29]

I used vinegar and let it sit a month, then back flushed the block only, then the radiator only. Lots of rust came out and I refilled with water and a cup of baking soda. Ran it a day or two and repeated the flushing, then did it again. After the third flushing I filled the works with 50/50 antifreeze. I also installed a 160 degree thermostat in the upper hose, just above the water pump. (S0 far it hasn't moved) I had soldered the stat to a rolled piece of copper that I had made into a 1.5 inch pipe just barely able to pound into the hose. Seems to be working fine and so far no rust appearing in the antifreeze.Temperature after running a half hour or so is slightly higher than it was without the thermostat, but just about 180 in the upper hose above the thermostat. Usually 165 on the lower hose.

[ursus]

Any block that has been marinated in a gallon of muriatic needs to be rinsed well then marinated again in a solution of one pound of baking soda per gallon of water to neutralize the acid. As noted by a previous writer, muriatic acid will just keep on dissolving iron if not neutralized.

I saw a low mileage but very rusty diamond Model B block that received a stout bath in muriatic acid continue to dissolve over the course of a year. The guy that owned it commented on all the rust that fell out of it every time he moved it. By the time he took it in for boring and rebabbitting there were pin holes appearing in the top deck.

[wk2w]

Would certainly agree with others. At a minimum, flush entire cooling system with clean water several times. Adding baking soda on initial flushings can only help. Only when you're sure it's thoroughly flushed and neutralized, drain and add coolant.

[Dollar Bill]

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Not to pile on but comment for posterity. The problem is that although HCI will remove the rust you see (actually what you see is NOT rust, it is the already oxidized byproduct of the rusting process which you can not see) it will set in motion a process that will lead to more damage even though it appears as clean bare metal right now. Once the acid contaminates the iron (ESPECIALLY cast iron which tend to be somewhat porous) the chemical reaction that starts will be nearly impossible to stop. Some will say you simply need to neutralize the acid, much easier said than done, and while steps to do this will slow the damage it hardly ever stops it completely. The rust converter solutions both dissolve the oxide on the surface and form a phosphate that tends to stop the rusting process, the Hydrochloric (Muriatic) acid on the other hand will dissolve the oxides but as far as stopping the rusting process it will be like throwing gasoline on a fire! Once the metal is contaminated with HCI, it can really make a mess. It is not as simple as removing the iron oxides that you can see you must take into account the chemical process that you have started. In the future, use Phosphoric acid because it will remove the oxides and start the right chemical reaction that will leave a phosphate coating that will inhibit rust instead of accelerating it. The Phosphoric acid may take a little longer but it is definitely the better way to go.

[Chris Haynes]

Originally Posted by wk2w

Would certainly agree with others. At a minimum, flush entire cooling system with clean water several times. Adding baking soda on initial flushings can only help. Only when you're sure it's thoroughly flushed and neutralized, drain and add coolant.

Done repeatedly. :-)

[30 Tudor]

Not only bad with cast, but high carbon alloy steels are subject to hydrogen embittlement. Which can be caused by any acid, but HCL is the harshest.
The hydrogen can work its was in to the molecular structure of the steel and combine with it and form a gas that will build up enough pressure to break hardened steel.

The plating industry is very cautious of this problem. It doesn't hurt to study it out a bit.
A materials/metallurgist friend of mine in the nuclear industry assured me that a quick wash to clean wouldn't do any damage.(I am referring to hardened steel, not cast)

I am pretty anal, I would run water with baking soda for a while in the engine
if it had any Hcl put in it, just to be sure, then flush with phosphoric if nervous about rust.

[Brian in Wheeling]

So...what does the original poster, Chris; have to say?
Brian

[Chris Haynes]

Originally Posted by Brian in Wheeling

So...what does the original poster, Chris; have to say?
Brian

I can't say anything other than what I posted above. Cleaned, rinsed repeatedly with BS and water, then lots of water. Now my radiator is full of vinegar in an attempt to get all the rust out of it.
The next thing will be getting my beat up old radiator re-cored.

PS I just noticed that the vinegar I bought at Costco is only 5% acid. Its not working very well.

[denniskliesen]

Vinegar takes a lot of time to do it's thing. I ran it straight for a few days and I know it wasn't long enough to do much good, so patience is your best virtue. I did quite a few flushes after dropping it pulled the lower connection off to give it a fast dump and refilled with 50/50 coolant. I know glycol can make it run 20 degrees hotter but the 3 row tube and 10 fpi recore has proven itself to be adequate. I also have a 160 thermostat as close as possible to the upper neck.

[Tom Wesenberg]

Originally Posted by Chris Haynes

I can't say anything other than what I posted above. Cleaned, rinsed repeatedly with BS and water, then lots of water. Now my radiator is full of vinegar in an attempt to get all the rust out of it.
The next thing will be getting my beat up old radiator re-cored.

PS I just noticed that the vinegar I bought at Costco is only 5% acid. Its not working very well.

I had to run the vinegar for 30 days to get the rust flakes out of my system, and even then I used a sump pump to back flush the block and radiator and got out some more junk. If I ever have to do this again I will use Evaporust.

[Chris Haynes]

Originally Posted by Tom Wesenberg

I had to run the vinegar for 30 days to get the rust flakes out of my system, and even then I used a sump pump to back flush the block and radiator and got out some more junk. If I ever have to do this again I will use Evaporust.

Evapo-rust is 23 bucks a gallon. I'll wait on the vinegar to do ts job.

[Brentwood Bob]

Chris, when you remove the head look at the back of the block. Behind Number 4 there might be some blockage. I used a probe and air to clear it. Put rags in the cylinders first.
Bob

[Tom Wesenberg]

Originally Posted by Chris Haynes

Evapo-rust is 23 bucks a gallon. I'll wait on the vinegar to do ts job.

That's the drawback.
I wonder how molasses would work? I've used it to derust some other parts, and it did a good job.

[Chris Haynes]

Originally Posted by Brentwood Bob

Chris, when you remove the head look at the back of the block. Behind Number 4 there might be some blockage. I used a probe and air to clear it. Put rags in the cylinders first.
Bob

Thanks for the tip.

[Dollar Bill]

Vinegar is one of the cheaper/safer/time consuming solutions for rust removal but it will leave debris in your cooling system and flash rusting will result in rust colored coolant until the block is passivated.

Phosphoric Acid will clean and convert rust but will not remove rust chunks.

Evaporust type products are chelation agents that bind tightly to oxidized iron and pull it into solution so there will be no chunks left behind as with acids.

I’ve used both Evapo-Rust and this much cheaper version and cannot tell the difference other than cost.

Chelation agents are the more costly solution but provide the best results - They can also be used more than once.

[Tom Wesenberg]

Thanks for the link to RUST 911.
That looks like the thing to buy, and I'll use that the next time I need to derust a block.

[Pinstripe]

Originally Posted by Tom Wesenberg

Thanks for the link to RUST 911.
That looks like the thing to buy, and I'll use that the next time I need to derust a block.

I've used Rust911 for 5 yrs. with superb results. It is an excellent product.I just do not understand why people play around with acids when this superior product is available. Works really well to derust the inside of the gas tank. It comes out spotless.

[ronn]

PS I just noticed that the vinegar I bought at Costco is only 5% acid. Its not working very well.


5% is normal for vinegar

I left it for 6 weeks in my 12 Buick radiator and it did a marvelous job! cleaned it out good.

Patience is a virtue.

[harleytoprock]

Chris, Muriatic will remove rust much better and quicker than vinegar. I'd try the muriatic again. For your baking soda neutralizing solution, add some liquid clothes detergent to it. The phosphates help to neutralize. I use 2oz of soda plus 2 oz of detergent per gallon of water. Leave the solution in there for about 15 minutes before rinsing.

[Chris Haynes]

Originally Posted by harleytoprock

Chris, Muriatic will remove rust much better and quicker than vinegar. I'd try the muriatic again. For your baking soda neutralizing solution, add some liquid clothes detergent to it. The phosphates help to neutralize. I use 2oz of soda plus 2 oz of detergent per gallon of water. Leave the solution in there for about 15 minutes before rinsing.

The Muriatic acid did a great job on the engine. I was concerned about putting it in the radiator.

[Tom Wesenberg]

Originally Posted by Chris Haynes

The Muriatic acid did a great job on the engine. I was concerned about putting it in the radiator.

My uncle's swather was overheating, so I put some muriatic acid in his radiator to clean it out. It cleaned it out so well it opened about 20 pin holes in the old radiator. I had to adapt a 62 Chevy radiator to fit it.

[Bruce of MN]

How necessary is the baking soda flush after using vinegar?

Here is the bucket after my first vinegar flush; pretty nasty! To make draining easier, I jacked up the front until the 5 gal bucket fit under the engine pan.

[BoysToys1928A]

I have heard that raw milk is a great neutralizer of things that are acid or to alkaline. For a chemical burn the fastest way to cool it and safest way is raw milk. Not a chemist but would the milk stop any acid from continue to eat away at the metal? Larry

[Dollar Bill]

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Vinegar is acidic and must be neutralized to stop the chemical process you started with the vinegar.

Baking soda will be cheaper than milk.

[Kevin in NJ]

In my reading, muriatic acid is never a good thing for rust removal. The damage can continue long after you think it looks pretty.

I did find that electrolytic rust removal will remove the left overs from the acid in my reading.

I have found the good old wires and manual removal of the rust to be a great way to get rid of all the stuff in the block. Keep in mind not all what you find is rust. I was removing some casting sand too. Plus not all the flaky stuff, what you really need to remove, will come out with chemicals alone.

[Tom Wesenberg]

I agree with Kevin, and would never use muriatic acid as a rust remover. Just the fumes from the acid will rust all the metal in the room where it's stored. I now store it outside.

[Tom Endy]

Originally Posted by Brentwood Bob

Chris, when you remove the head look at the back of the block. Behind Number 4 there might be some blockage. I used a probe and air to clear it. Put rags in the cylinders first.
Bob

I have a magnet on a long flexible shaft. Also just a long flexible shaft. I put the shaft in a reversible drill motor and go down through all the water jackets in the block where rust wants to settle. The back ones will be the worst. After a few licks in both directions with the drill motor run the magnet down and you will be surprised at how much rust is on the magnet.

Alternate the drill motor/shaft and the magnet until you have it all cleaned out or you are tired of doing it. You can get to all the water jackets from the top of the block. Also a good idea to remove the water inlet casting and go in through there. Periodically blow shop air through the jackets. The head usually does not clog with rust, but it is easy enough to clean it the same way.

Once the head is back on I attach some fixtures I made up that will connect two garden hoses at the inlet and outlet castings. I then connect it to the hot water tap for the washing machine and let it flush until clean water comes out. I then reverse the hoses at the inlet and outlet and flush it more. This is done with the radiator off.

Then I connect my fixtures to the radiator and repeat the procedure.

This does a good job of eliminating rust from the block. The radiator however may have to be taken to a radiator shop and have the top and bottom tanks taken off and all the tubes rodded out and flushed.

Tom Endy

[1928Pickuppain]

Im currently doing a "cleaning" just finishing up after two weeks. I first filled my system with degreaser and ran that until hot and let cool and repeated about 5 times a day for 2 days. i drained it into a bucket and it came out black black black and slightly thick.

Then i filled the system with gasoline ran for 5 min until it started to get hot, boil (vapor lock) and let it cool for 35 min then repeat two more times. i drained it into clean white bucket it came out black black black and settled into some awfull stuff at the bottom. I repeated this one more time and got alot less black results but still dark grey. I then flushed the system back and forth and got large rust chunks and sandy bits out of both radiator and motor. Then i fulled with evapo-rusted leaving it overnight Starting it just to make sure it really pumped through the system. Again it came out black as night. flushed again with water till clear then ran gas again. Once again the gas came out black as all hell and then flushed with water until clear. I then ran Dawn Dish soap in there for about two hours as it ran in the drive. I flushed and got dark brown and small rust chunk. I then ran vinegar 2 quarts worth mixed with water as i drove the car around everywhere for two days. When i flushed it came out dark almost blackish crimson and with a slight viciousness to it. I flushed with water getting only small sandy flecks out and repeated the vinegar and driving for another 3 days. Today it flushed out still a crimson but a lighter brownish crimson. I flushed again. filled with gas, ran till hot, and left over night, in the AM i will drain and flush before filling it with a gallon of ammonia, a quart of hopps powder cleaner and a top it off with a gallon of water with about half a cup of dawn dish soap. I will let is sit for 20-30 min and this will strip the brass radiator of any scale, hard water residue or really ANYTHING, left on the brass radiator itself. (I use this method to clean clock movements after disassembly) it will strip them down even heavy oxidation to the point of pitting and after rinsing it will leave you with bright shiny almost polished looking brass. Then i will flush with water and fill with a 65/35 coolent mix.

I dont necessarily recommend the gas and ammonia all this if you have any nabors as they may kill you. I had my neighbor Jerry come over a few times to make sure i wasent going to blow up the neighborhood (and he puts up with alot of crap from his white house turning back every year form the soot from my stove pipe burning waist oil to compressors and small explosions going off at all hours of the night! Poor bastard but i know the ammonia and hopps will just about drive him from his house tomorrow HaHaHa

[Chris Haynes]

I found that RUST 911 does a remarkable job of cleaning water passages.

[Cool Hand Lurker]

Originally Posted by Tom Wesenberg

That's the drawback.
I wonder how molasses would work? I've used it to derust some other parts, and it did a good job.

Tom, I put a flathead V8 in a 55 gallon plastic barrel that was filled with water and one gallon of agricultural molasses for three weeks. As the scum came to the top it was scooped into a 5 gallon bucket. When the bucket finally dried out completely there was a layer of solid rust residue about 3" thick in the bottom. The block came out looking like new iron.

I have tried electrolysis, phosphoric acid, muriatic acid, Evaporust, vinegar and a couple other solutions. All of them give good results but none were better than the molasses. It works, it is safe and it is the only method I use now.

[Purdy Swoft]

Has anyone tried red devil lye ?

[Pete]

As most people know, model A guys will go to almost no ends to save a couple of dollars, no matter how much it costs.
Aside from spending the $75 dollars to have a block commercially stripped, there is available a cheap, simple test to tell if there is any acidic residue left in the block. It is a litmus test kit. It will test for both acid and alkaline residue and you don't have to be a rocket scientist to use it.