VCCA Home Forums TECHNICAL - GENERAL Mechanical - Engine, Trans, etc Flushing With Muriatic Acid...

Just reading about how flushing radiators ( out of the car of course ) with Muriatic Acid really cleans things up...Being from under a rock I had never heard of this solution before...

Anyone else try this method before...?

Muriatic acid is very hazardous if not handled correctly. It takes several pieces of protective equipment, a thorough knowledge of handling procedures and consequences if not done properly. It can be highly corrosive to ferrous metals as well as the solder that holds the radiator together. If the acid is safely diluted then the hazards can be minimized.

Granted it is HC...But, it was mentioned that a dilution of two parts water was good...They also said if you get it on ferrous material it cleans it up quite nicely but you'd have to neutralize afterwords and dip in oil...The claim was that it will do as good a job as a radiator shop...

I ask this question because I'd never heard of it before and I'm trying to avoid a very $$$ repair bill on a radiator that is no longer available...

The problem with most old radiators is that some of the tubes or passages are plugged with crud. If that is the case then it takes hours, days or weeks for a cleaner to penetrate far enough to clear the block. So it either takes a pulsating cleaning system or physically removing the blockage. If there is only a coating on the radiator surface then a chemical cleaner can be very effective in a relatively short time. High concentration cleaners can not only be corrosive but in localized areas can generate enough heat to destroy the solder bond rendering the radiator scrap metal.

The automotive aftermarket is fraught with claims that can not be scientifically substantiated. They use case histories and anecdotal "facts" to support the claims. Just remember that over the years millions (actually billions) of $$ have been spent by the major companies researching possible improvements. If they don't support a claim it is probably not a wise idea to believe the hype.

I'm reading that the old radiator shops in fact used muriatic acid to "boil" out their radiators...I read it on the Internet...!

Well then.....that explains the whole thing!

Chipper,
At a local old-time mom 'n pop hardware store, I found some Texaco radiator cleaner. It came in a tin can with a lid on each end. The can was compartmented so that one end contained oxallic acid to flush with, and the other contained bicarbonate of soda to neutralize the system after cleaning. I used it on one of my cars, and it appeared to do a pretty good job. I bought several cans of it for possible future use, as the radiator flush solutions they sell now days don't seem to do much of anything.

I'd wondering how aggressive oxallic acid is, and if repeated flushings with it pose any risk of damage to the radiator or engine block and head.

Mark

Oxalic Acid is one of the stronger organic acids. It was very common as a major component in radiator cleaners until the use of aluminum in engine and cooling system components. Modern cooling system cleaners are designed for the aluminum systems not those in our old Chevys. Cleaning with Oxalic Acid is similar to cleaning with dilute Muriatic Acid. Both require extensive flushing and neutralization (Sodium Bicarbonate aka baking soda).

"He's a french model...I met him on the internet...!"...ah...bonjour...!"

I have been following this interesting discussion and have a question or two.

I have been using Oxalic acid for many years when soldering the lead on lead-lights. Its a very effective cleaner for lead. My thoughts that if used in radiators joined together with lead, then it could possible do more harm than good? Especially if not neutralised in some way, and it would have to be 100% effective, or the radiator joints would be eaten away?

Second question: Having been through recent radiator troubles, I read every chapter in my chevvy manual and other books on "radiators".

One item that kept cropping up was the use of LEY to clean radiators in the olden days.
It had to be diluted with water.
I have never heard of LEY, does anyone know of it and its use?

Peter

Peter,
Are you asking about "lye"?

Sodium Hydroxide is the name for lye. Draino etc use it.

Oxalic acid is very good at removing the oxide layer from solder. So are several other organic and mineral acids. Flushing and neutralizing therefore is critical not only with solder but the other metals in a cooling system.

Lye or sodium hydroxide is very effective at removing oils. Not so at removing rust or scale deposits. When a headgasket failed lye or NaOH was used to help remove the oil that inhibited heat transfer.

Oxalic Acid...? No, no problems with it attacking anything short of minor surface cleaning on lead, and that's at melting tempertures, That's why it works as a "flux"...Oxalic acid...That may be an inexpensive way to do it...But, even typical soldering flux must be thoroughly cleaned off to prevent later oxidation problems...Soapy water works...Right after the work...

Radiators used to boiled in a solution of some cleaning compound. I can't remember what it was called. It was a regular commercial product used for that purpose.

Merely boiling the radiator usually wasn't good enough, though. What was generally needed was for the top tank to be taken off (unsoldered) and it and the core and attached bottom tank throughly boiled.

After the radiator was boiled and then taken out of the tank, a water hose was attached to the bottom outlet and, with water constantly running, each flue was rodded with a piece of strap steel. (Sometimes not all flues could be cleared but usually only an insignificant few.)


After rodding, the top tank was cleaned using the brush side of a bench grinder and then it and the top of the core were cleaned with cut acid (sulfuric, I think I recall, using pieces of jar lids) so the solder would flow and seal better. (All this was a long time ago for me to remember it all.) Anyhow the top tank was reattached to the core.

After that the radiator was pressurized with about 10 pounds of air via the overflow tub whilst all other outlets were plugged. It was then dipped (raised and lowered) horizontally in a vat of water to detect and repair leaks. Very, very tiny seeps on a radiator such as a Harrison were not chased but a little Solder Seal was used to take care of them after the radiator was reinstalled.

Sometimes some flues had to be cut out because they were damaged by a fan or other reasons. One could eliminate several of them without causing any effect on the cooling system. Most radiators back then were highly efficient and without a thermostat would run way too cool anyway.

If the radiator was too damaged or too many flues couldn't be cleared by rodding or there were too many leaks under pressure, both tanks (bottom and top) were removed and installed on a new Harrison or McCord core.

Sorry this so long and didn't intend for any blah, blah.

Kevin, I don't recommend using any of that commercial cleaner solution. It will likely make the situation even worse. Instead I'd look for a competent radiator shop and, if warranted, a new core or radiator.

Best,
Charlie

yesyes

Kevin

Any attempt to clean a radiator might also remove residue that blocks water leaking from small holes in the system. ( do not ask how I know it !! ).
Best is to let a good radiator shop re-core your radiator then you will have a trouble free radiator and enjoy your ride without overheating problems for many years to come. I re-cored my 68 Volvo Amazon 23 years ago and used it as a daily driver for some 10 years and even now with limited use is still in perfect working order.I also re-cored my 48 Fleetmasters radiator 3 years ago and so far the temperature never went more as 170 F.even in the warmer summer days (using a 160 F thermostat )

Jianis

Okay...Here's the deal...I'm wasn't going try this on my car radiator...I have a Toyota Fork Lift that the radiator is no longer available for ( as in it's not even made any more ) And one quote to re-core was $900 dollars +...At this point I'm ready to try almost anything...I heard Drain-O might work...!

Kevin
By that post I guess you have been to the radiator shop already. In that case I am surprised they dont have a listing for cores by size even if the replacement has extra row of tubes.
Tony

Thanks, Tony...I was a bit shocked by the "quote"...Naturally it does indeed have an extra row of tubes...In fact, what I found very unusual ( well, to me anyway ) was that the rows of tubes appear "staggered"...You can still see thru the core but it's obvious that their not lined up...Never have seen anything like it before...That and the fact that the fan blades come within a 1/4 of an inch of the radiator on some...A couple others are about a 1/2 inch...I don't believe the fan could possibly be bent/damaged...How could it ...? It's to well protected...

There must be a reason for the changing blade pitch/clearance ( I don't know what else to call it )

i went to the local masonry supply to get some muratic acid and was told that almost no one will be selling it soon. the feds have a ruling about who can sell it and to whom, the guy has to go to a training and certifying clinic soon. something about how it can be used to make explosives. my chemistry study did not show how to do this, but theirs is apparently superior.
i used muratic flush for mine, neutralized it and rinsed. seems to cool just fine.