The Stovebolt Site Forums The Shop Area Engine Shop Replacement Radiator for 1940 1/2 Ton

I am having a problem trying to find a replacement radiator for a 1940 1/2 ton pickup.

I have an original radiator that fits fine (appears to be a 1939 model part #3113455) but have found that there are a couple of leaks in the top tank. I have considered trying to patch them up (at least temporarily) while I find out if the engine in my project will actually run. If someone can suggest an epoxy or other material that might work on an unpressurized system, at least for a while, I would appreciate hearing about it. If the motor runs, I will be more confident about spending the money for a new radiator.

In the mean time, I have looked online for new radiators and all the photos that I find of radiators that say they will fit a 1940, seem to have the filler neck in the wrong location, or too short to reach through the sheet metal that covers the top of the radiator.

There don't seem to be many '39 or '40 models that post on this forum, but if anyone has experience with a new radiator that actually fit one of these, please let me know which one and how it has worked out. Some folks by cheap radiators and love them...others don't have such good luck.

Nick,
Maybe someone, one of the grey beards around here, can chime in on just how hard it may be to patch a radiator the "right" way and just how to do it???

It seems to me that if you know where the leaks are, and you have the ability to braze (or whatever the method is), shouldn't we be able to do this? Assuming the leaks are in a spot that's easy to get to, etc.

Maybe it *IS* hard ... ? If someone could set the record straight here. It just seems like we shouldn't have to scrap a radiator just because of a couple of leaks...

John

I don't know how much the '39-'40 is different from the '36-'38, but my original '37 radiator was a non-pressure I had converted to a pressure system. I ran a 4 lb cap so not all that much pressure. Every time the engine was started from cold, the top tank would POP when it was heating up and getting pressure on it. This lead to cracks at the solder seem. About once a year I would pull it out and solder the seem shut and go again. I finally replaced it with a AFCO brand aluminum which at the time was pretty good investment. Mine sets forward and down from factory due to the 250 inline six, but it did match up to the original. I altered the side plates to fit my truck. I still have the AFCO but wouldn't buy another one, the tubes are epoxied into the end caps. I would want a fully welded aluminum or soldered brass next time. I fixed a couple leaks with some 3M epoxy that's been holding so far.

Clean the leaking area with a stainless steel brush and make sure it's dry, then use a soft flame propane torch or if you have one a solder tip for a propane torch and just repair what you have. With the solder tip, no flame hits the tanks and the heat is much easier to control. I found it to be pretty easy to fix them.

On a side note, when I changed out my radiator, I wrapped the old one in heavy cardboard and put it up on a shelf out of harms way. I decided to sell it off to guy needing one and pulled it down to ship it. The top tank was totally destroyed, looked like it was shattered glass yet the cardboard was even scratched. All I could figure was the old brass just gave up and came apart from all the flexing, it was really thin.

Nick - In looking through a bunch of Chevrolet Master Parts Books, I found the radiator number listed for your 1940 KC should be 3113453 (vs your 3113455). Possible miss-read on your radiator??? I think your radiator is most likely correct for your '40 KC.

All my info for the '39s shows those standard duty 2" core radiators would have been "3112130".

The books all indicate the standard 2" core radiator for 1940 was the same used in all Commercial and Utility trucks, except those equipped with the COE's and 3" core heavy duty radiators. All these numbers are also confirmed in this listing from The Brass Works. They do restorations of existing as well as reproductions of many radiators, but you can expect to sink a large chunk of change and long turn around time based on what I read in the site.

Can you post some pictures of your radiator?

Nick,
I fixed a leaking 1955 For@ tractor radiator last year with Rapid -set Marine Tex. Worked great so far. As far as fixing it I spoke to a few people & stovebolt members . Seems my best move was the Marine Tex. Unless you have skills with heat & brazing.
Just my real world 2-cents.
Todd

Is there no radiator repair shop anywhere within 100 miles of you?

Try to find one. Driving to it will be worth your while.

Unless the tubes are completely corroded inside, radiator repairs are not difficult and are relatively inexpensive. My local radiator shop will boil out any radiator and solder any leaks for $90.

Repairing your original copper/brass radiator will normally be a lot cheaper than buying a new one of typical inferior quality.

Thanks for all the responses.

I had seen that Brass Works listed 3113455 as a 2" core for a 1939. My radiator does show "39 K" just above where the "3113455" is stamped into the tank. I was not too worried as to whether or not it would cool my 235 engine, as I don't see me working the truck very hard. Also, I thought that there was a possibility that it was actually the original radiator that had been installed in the truck as the "39 K" on the radiator makes me think it was manufactured in November of 1939, and the truck ID tag indicates that the truck was assembled in December of 1939. Also...the radiator fit where it was supposed to. So all that together made me think that it was good enough to be worth trying.

I did call the "local" radiator shop that was recommended as the closest that could test my radiator and either fix it or declare it dead. They are 132 miles away! They listened to what I had to say about my radiator and since it is a couple of hours drive to get there to drop it off and again to pick it up, and since their rate is $162.50/hour (said it would probably be a minimum of 1 hour to assess its condition), that unless I am absolutely wanting to stay with the radiator I have for originality's sake, they said that it might make the most $$ sense to purchase a new radiator. (Again, if I find that the engine runs as well as the story that came with the project, purchasing a new radiator will sit a lot more comfortably than purchasing one for an untested engine.)

From the responses, it looks as though I should either solder the leaks in the tank or epoxy them. Since one of the leaks is close to the tank/core seam, I would assume that there is the concern about messing up the seal between the tank and core.

If I epoxy the leaks, so far it looks as though Marine Tex is the recommendation. Is there a specific Marine Tex that would be the best guess? Any other suggestions based upon experience?

I have attached photos of the ID stamp on the radiator, of the two spots that are known to be leaking (surrounded in red grease pencil), of the overall front and back of the unit, and of the radiator as seen from the front behind the grille.

I really do appreciate all the suggestions and comments!

Ya, the hourly rate thing would turn me off, too. The local shop here charges a flat rate to boil out and solder leaks and won't charge you if they determine that it can't be repaired.

I took them a '66 Mustang radiator and they told me it couldn't be repaired but needed to be re-cored for $400.00. Instead they got me a brand new copper/brass radiator for $200.

Ol' Roy's 1941 Harrison was hot tanked and soldered a couple years ago for $90. I wish you were closer to Atlanta.

You might be able to repair it yourself. If it's leaking already, you've got nothing to lose by trying.

That radiator looks to be in excellent condition. I wouldn't hesitate to grab a soldering iron (one of the ones with a big chunk of copper at the end) and solder up those cracks. I might drill the ends of the upper one, but cleaning the area and soldering should make it leak-free. Easy enough to test for leaks by installing the cap, laying it face down, attaching a couple of foot long pieces of radiator hose and filling it with water. Or getting a couple test plugs and applying about 5 psi of air and use some soap solutions to check for bubbles.

Nick - I stand corrected sir. I missed the '39 listing with the 3113455 number. Great pictures and info BTW!

I agree with your surmising the "39K" is most likely November 1939 build date, which would coincide with the 1940 Model year, I think.

A closer look at your pictures shows it's already been to at least one radiator shop since new. The Ft. Collins Radiator numbered tag above the upper radiator hose neck attests to that.

I'm with Kevin on attempting a self repair. I would suggest that when you start trying to clean off the paint for soldering or applying the Marine Tex, be extra gentle with a hand operated wire brush using light pressure. The brass tank could suffer damage if you get too aggressive with the wire brush.

Kevin, I had to laugh at myself when I read your suggestion of laying the radiator face down and using a couple of feet of radiator hose to get water into it to test it! (I could have saved myself some $$ if I had been smart enough to come up with your plan!

I am attaching a couple photos of a soldering iron I have on hand that has a bit of a larger tip on it. Is it as large as you think I should have, or are you suggesting one of those irons that are about 1" wide? (Serious question!)

Try these folks. They make a very good product.

https://ecp-radiator.com/collections/chevy-radiators

Geoff,
Unfortunately, it seems that they only make radiators for Chevys back to 1948!

The AD radiator is $400, anyway. For that kind of dough you can have yours re-cored.

Nick, I'm suggesting one of the old school soldering irons, like THIS. Heat them up in a small furnace or with a torch. They hold their heat long enough to do the job you need. Electric soldering irons are for soldering 16 gauge or smaller wires. They're not up to the task of soldering radiators.

These are the type of tips I have, it came with my torch set years ago. They slip over the end so the flame heats the tip, the flame shoots out the side holes. Once hot, you can solder with out the gas on.

Joe's suggestion of using a soldering tip from a torch kit would work as well. Turning the flame off first would be a good idea. I have a small butane soldering torch kit and the flame coming out the side can cause problems of melting things you don't want melted.