Honeycomb radiator external cleaning

[Hubert_25-25]

I have a honeycomb radiator that appears to be in very good shape.  It came from Oregon, but who knows where it spent its glory years.  There is a light brown dirt that has baked onto the honeycomb core.  You can see the outline of the shell at the top of the radiator.   I guess years of driving down dirt roads and a hot radiator can do this.  On the last slide, you can see where I use a pick to clean a few rows, but this is very time consuming to clean 6 sides of each honeycomb.  I did try cleaning it with a toothpick, but it was even slower.  I did have it soaking in a bath of water and simple green for about a week, and it seemed to soften the dirt some, but you still have to scrape it to get it off.  I tried a little oven cleaner on a q tip, but that stuff left a small bare copper spot so it likes solder, so I abandoned that idea.  I tried some CLR the same way with a qtip, but it did not seem to soften the dirt any more than the simple green.  I know these honeycomb radiators were just exposed silver colored solder, so any guidance for cleaning would be much appreciated.

Thank you,   Hugh   

 

[Mark Shaw]

I suggest using lacquer thinner with a brush to remove the dirt. 

 

Do you plan to paint it?  I have heard some restorers use black liquid shoe polish instead of paint to retain heat transfer properties.

[Spinneyhill]

4 hours ago, Mark Shaw said:

Do you plan to paint it?  I have heard some restorers use black liquid shoe polish instead of paint to retain heat transfer properties.

 

I seem to remember looking into this. It is a myth.

 

This is from a M.Sc. thesis in 1956 (scholarsmine.mst.edu/cgi/viewcontent.cgi?article=3195&context=masters_theses):

 

So what softens "dirt"? Plain old dish washing detergent and water. You could speed it up by making a "gang" prodder of toothpicks or similar to prod several opening at once. Once you remove the plug, let it soak some more so it is easier to clean off the surface. Can you use a spray gun cleaning "bottle" brush to finish?

[25 Buick]

Pressure washer?

[Spinneyhill]

3 hours ago, 25 Buick said:

Pressure washer?

LOW pressure washer 'else you will bend the fins. Garden hose might be enough. I wondered about air from a small orifice, but very carefully.

[Terry Wiegand]

The idea of a pressure washer at a distance to start out with and plain old dish washing detergent doesn't sound like a half bad idea to me.  If that doesn't work take it to your local radiator repair shop and have them tell you how to clean it up or have them clean it up for you.

 

Terry Wiegand

South Hutchinson, Kansas

[Mark Shaw]

18 hours ago, Spinneyhill said:

 

I seem to remember looking into this. It is a myth.

 

This is from a M.Sc. thesis in 1956 (scholarsmine.mst.edu/cgi/viewcontent.cgi?article=3195&context=masters_theses):

 

So what softens "dirt"? Plain old dish washing detergent and water. You could speed it up by making a "gang" prodder of toothpicks or similar to prod several opening at once. Once you remove the plug, let it soak some more so it is easier to clean off the surface. Can you use a spray gun cleaning "bottle" brush to finish?

 

Spinneyhill,

     You sure are quick to condem my post as a myth when I only offered some first hand experience from other antique car restorers I know.  I find it hard to believe your quoted source (some college kid in 1956) when the data is based on steam heat loss due only to convection.  The restorers I referred to have been doing this for many years before modern radiator paints were available.  Eastwood, who specialize in antique car restoration, recognized that automobile radiators require special heat transfer coatings.  See the underlined sections in the example below:

 

Eastwood Radiator Black 12oz Satin Finish

Normal engine paints are too thick for radiator use which will interfere with heat transfer and block air flow over the cooling fins. Also, standard paint tends to flake off metal radiator tanks. Radiator Black is specially formulated to solve these problems and is heat resistant to 300°F.

• Factory Look Finish
• Heat Dissipating Formula
• Quick Drying
• Heat Resistant To 300° F

Durable Enamel formulation resists temperatures up to 300ºF, under hood chemicals and chips. One can covers 6 square feet (most radiators require 2 cans). Net wt. 12 oz.

 

Radiator Black Satin - Many have asked for a lower sheen radiator black. The lower satin sheen resembles the gloss level of modern plastic tank radiators and some imports. Durable Enamel formulation resists temperatures up to 300 degrees F, gas and chipping. One can covers 6 square feet most radiators require 2 cans. Net wt. 12 oz.

http://www.eastwood.com/ew-radiator-black-12oz-satin-finish.html

 

 

Edited September 6, 2017 by Mark Shaw (see edit history)

[25 Buick]

Obviously not a industrial pressure washer but a small home one. The fins are stronger than you may think. Not like today's radiator designs.  However caution at first. 

[Thriller]

While still labour intensive, when the crud is soft, a pipe cleaner of appropriate size might help. 

 

[Hubert_25-25]

First I want to thank everyone for your suggestions.  They are all very helpful.

Mark, I tried lacquer thinner.  It did not cut whatever dirt is baked onto my radiator, and it evaporates quickly, and even though I tried repeated applications and keeping it wet by using a qtip, it just was not softening this material.

So I soaked a q tip in several things that people suggested. The 3 q tips used, and I have simple green (on the bottom) , CLR (middle) , and Gunk engine cleaner on the top.  The middle one (CLR) and is the only one that seems to be removing this stuff.  I also notice that after a while, I begin to see some pink, which I assume is the copper.  Not sure if this stuff is removing some of the solder, so I cant leave it in the solution for too long.  This is full strength too.

 

In the bottom picture, the top 3 rows are hand cleaned with a pick, and on the 2nd row below this in the middle you can see the 1 hole that I used the CLR in. 

 

My plan is to soften the crud first if this is possible, and then flush it off, but trying not to get too aggressive.  So I have a big plastic tub.  I plan to mix CLR and water and put 1/2" of liquid in the tub and let it soak.   Then check it a few times and begin either garden hose washing it, or power washing it without getting too close with my house unit.  

 

These old radiators are supposed to be solder colored, and I will not be painting it black.  The shoe polish Idea I like and there are some silvers out there.

 

Any comments are welcome and appreciated.   Thank you

 

Hugh

[Mark Shaw]

Hugh,

     Your close-up photos clearly show a build up of calcium carbonate, so CLR is definitely the best agent to use...

[Hubert_25-25]

Mark, 

    It could be that this car spent a lot of time on a Caliche road.   I am used to cleaning the crud out of the inside of radiators.  Hugh 

[KongaMan]

3 hours ago, Mark Shaw said:

Hugh,

     Your close-up photos clearly show a build up of calcium carbonate, so CLR is definitely the best agent to use...

 

Vinegar might work also.  It's not quite as strong (which might be a good thing), but it's much cheaper.  IIRC, CLR is ~$28 a gallon, while Costco sells vinegar for around $2 a gallon .  If you can find a tub bigger than the radiator, you can submerge the whole thing for not much money.

 

If you want better control of a pressurized spray for small spaces, try a WaterPik.

[Spinneyhill]

On 9/6/2017 at 2:52 PM, Mark Shaw said:

 

Spinnyhill,

     You sure are quick to condem my post as a myth when I only offered some first hand experience from other antique car restorers I know. 

     

OK, maybe I have made an idiot of myself, again, but jumping in too quickly and not reading the statement carefully enough. Sorry to jump on you like that.

 

Well, lets look at the science and see where we get to.

 

How does an automotive radiator work? Heat transfer is by either conduction (which requires physical contact between two objects), convection (by fluid flow - air is a fluid) or radiation (surfaces exchange electromagnetic waves, such as light, infrared radiation, UV radiation or microwaves). Clearly, an automotive radiator is not an efficient "radiator" - it doesn't radiate much heat, you can't feel much heat a foot away. A little is conducted away into the car body. The bulk of the heat transfer from a radiator is by convection - the heat transfers from the metal surface into the air moving past. In fact, it is forced convection: the air flow is forced by vehicle speed and the fan. So it is not really a "radiator" at all, more a convective heat exchanger.

 

OK, so now we have the main mechanism of heat transfer from our automotive radiator - convection from a metal surface into moving fluid (air).

 

I note the "college kid" was Richard F. Justus and the superviser was Dr Glenn Brand, Associate Professor of Chemical Engineering. Mr Justus was 28 when he submitted this thesis and had been working as a chemical engineer for several years prior, after obtaining his bachelor degree.

 

The last paragraph of the Introduction gave the object of the investigation: "to determine heat lost from a painted pipe about 50 °F above a room at 70 +/- 20 °F and determine heat transfer coefficients of paint films and the effect different pigments have on the coefficients." That seems to me to clearly apply to our situation: losing heat from a painted metal surface about 50 °F above ambient temperature. He was determining overall coefficients for convection.

 

His "paint" was a pigment in linseed oil and a drying agent, self made. The pigments were carbon black, titanium oxide and calcium carbonate (white) and aluminium powder (silver). These probably best approximate shoe polish rather than modern paint. The pigments filled the surface roughnesses on his pipe, driving off corrosion oxides.

 

His white and black "painted" surfaces had higher coefficients of heat transfer than silver and especially unpainted.

 

But what about real paint? Thermal conductivity of copper is c. 380 W/m.°C. Solvent borne paints appear to have thermal conductivity of about 0.17 W/m.°C (https://www.thefreelibrary.com/Special+heat+capacity+and+thermal+conductivity.-a0228354685 ), which is about 0.5% of copper. Based on this, one might think one had best make the paint really thin so the thermal conductivity (which will slow heat flow to the surface) has a very small effect, otherwise it could be an insulating layer. I am still looking into this and have downloaded a textbook on heat transfer for bed time reading (http://web.mit.edu/lienhard/www/ahtt.html

) .

 

A quick scan seems to show forced convection cooling is really a function of surface roughness. Paint will smooth a rough surface. Shoe polish not so much, leaving little more than a layer of pigment. So the pigment replaces corrosion and maybe smooths the surface a bit in Mr Justus's experiment and improves cooling.

 

I will come back on the effect of paint.

 

As for cleaning the radiator, it does look a bit like scale but examine carefully to ensure it is not corrosion oxides. CLR is acid and removing the lumps could lead to leaks.

 

[Hubert_25-25]

I tried the vinegar, but it would not soften the calcium.  I did purchase a water pick which is helpful, but not strong enough.  It will come in great for cleaning orifices in carburetors.  

 

Hugh

[KongaMan]

Vinegar isn't an instant solution; you need to give it time to let it work.  That's why you soak the parts for a couple of hours.

 

If you want something faster, try muriatic acid.  But be very careful: the fumes are nasty and it will eat metal if you leave it on too long.  If you do opt for this, dilute it well, work outside, don't let it soak too long, and rinse it very well when you're done.  Personally, I'd use this only as a last resort.

[Spinneyhill]

After you use any acid, but esp. muriatic (=hydrochloric) acid, neutralise afterwards with a sodium bicarbonate wash. Pool shops sell sodium bicarb. or pH buffer fairly reasonably, by the bucket.

 

Vinegar (acetic acid) is a weak acid and will take time. CLR is stronger. HCl (undiluted) is strongest and will act soonest and require careful management and attention to safety. Wear gloves and safety spec''s and a plastic apron if you use the strong stuff. It will damage your clothes and you will only notice the holes after they are washed.

 

I am with KongaMan. HCl is the last resort for the impatient (like me!).

Edited September 9, 2017 by Spinneyhill
typo (see edit history)

[1928Buick]

hi Hugh....try WD-40 sprayed liberally in each comb, and triple-zero (000) steel wool wound tightly around a q-tip. tho marketed as a lubricant, WD-40 invented by Bell Labs is actually a cleaner. I've used it to great success on a number of preservation projects.

[25 Buick]

You are talking about white vinegar.