I bought a new 3 row copper/brass radiator for my 1956 Crown Victoria about 4 years ago from US Radiator for $480.. Changed 50/50 coolant/water at 2 years, Radiator is now leaking at a seam along the top area just below the radiator cap opening - where the top of radiator housing is welded to the core. I do not know how much it would cost to clean, repair and pressure check. I do not know how reliable the repair would be. Assuming the repair would be in the $200 range, do I get it repaired and hope for the best or replace it with a cheaper aluminum radiator for about the same money?
I thought at the time that by buying the more expensive copper /brass radiator instead to the more inexpensive aluminum one I would get a more reliable - problem free radiator. The car is only driven about 30 - 40 miles per  month as I was working full time. I am retiring at the end of this month and plan on driving it a lot more.
Any recommendations on a more reliable radiator?

I'm pretty sure the old style cooper/brass radiators are soldered not welded. It was a common problem for the seams to leak in the factory ones from expansion/contraction but shouldn't in your replacement. What pressure cap are you using # lb? Anything above 7 lb is pushing your luck.

Total agreement on using the 7 lb. cap on the oem mid-Fifties radiators.  That top tank presents a lot of surface area to the soldered seam there and any pressure in excess of 7 psi tends to make for premature leaks in the top tank area.  I struggled with those top tank leaks for years on my ’55 Customline but when the older guy at the radiator shop suggested using the 7 lb. cap, that solved that problem.  After several years with the 7 lb. cap, the radiator core finally got to the point that I switched the radiator to a replacement aluminum from Champion which came with a 13 lb. cap.  Because that new radiator does not have the oem style oversized top tank, I’ve been using the 13 lb. cap without any issues.

Lorena, Texas (South of Waco)

I don't like to suggest how people should spend their money but you have an expensive radiator and I don't think having the top tank soldered would cost that much.

After 4 years all it should need it to be soldered. Any good radiator shop should be able to do that for a lot less than $200.

I had the same mindset as you when I purchased a brass replacement from US Radiator. This was after I had the original radiator recored at a local shop for my 56 Victoria. It wasn't long before I had to return 3 times to have leaks resoldered on the top seam. With originality in mind, I too spent the $480.00 for the new brass replacement which looked great but also started leaking at the top seam after about a year of usage. (about 10,000 miles) I drive my Victoria daily. US Radiator offered to repair if I would ship it to them. I chose to have a local shop fix it $60 and the old time radiator guy that fixed it said that the aftermarket ones were not designed with the same bends internally . I ended up getting it fixed 2 more times with the radiator guy refusing to guarantee the repairs. Yes, using a 7 lb cap helped  but it seemed disappointing for such an expensive item to not operate to factory specs. 13 lbs. I ended up giving up on brass and ordered an aluminum replacement from Auto City Classics $229.00. I like the fact that it looks original with stamped upper and lower tanks and fit like an original with no modifications. I chose not to paint it in order to get maximum efficiency but in retrospect the aluminum replacement seems to keep the motor cooler than the brass and a coat of black paint probably wouldn't have hurt much. Seams are welded, not soldered and I have no regrets . 

I purchased an Aluminum Rad on Ebay from Champion Radiator. Installed in July so I can't say how long it will last or if there will be a problem with Workmanship. Made in China but distributed from USA. The Quality looks very good. Includes Transmission Cooler for Automatics. It fit with no Modifications. The Core is thicker than the Stock Core so U may have to move the Fan Blades back a little depending on what is on there now. Cools very well and has a 13lb Rad Cap included. Unless I was doing a 100 Point Restoration  I would purchase another One from Champion although I suspect these Chinese Rads are all made by same Manufacturer, Just sold under different Seller Names.  

  

We also bought an aluminum radiator made by Champion on Ebay for our 56 Ranch Wagon and so far so good. The only two comments I have are that the bottom tank configuration is different from stock which puts the transmission cooling line fittings at a different angle. The remedy for this is that I needed to bend the stock steel cooling lines. The other minor issue is that on my filler cap neck, the overflow fitting points to the passenger side rather than the driver's side, so if you want to install an aftermarket overflow tank there is a little less room on the passenger side due to the battery tray. Other than that, we like the Champion Radiator.

  Ron Lane,  Meridian, ID

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I had a Water Cooled Transmission installed after I installed the Rad. When the installer made up the Lines going straight into the Cooler the Lines  interfered with the Fan Blades by about 1/2 inch. Installer elongated the Rad mounting Holes so the Rad dropped down enough  to clear the Fan.  If anyone else is considering buying One of these Rads be aware there are 2 different Core Sizes so make sure You measure the existing Core Size and order the correct Rad. Champion has both Sizes listed.

  

On the subject of aluminum radiators: I built a '40 Ford street rod in the '90s and put a Griffin radiator with two rows of 1 1/4" tubes. It cooled the 5.0L Ford engine great for 12 years with the electric fan rarely kicking in. It developed a small leak and Griffin said to use Barr's stop leak in it. It stopped the leak, but it never cooled as well after that. A couple of years later I put a new radiator in with two rows of 1" tubes. It did reasonably well, but not like the Griffin originally did. Reading about radiators, it seems that the cooling is done by the fins and the wider the tube, the more contact area with the fins. The point is that a radiator with a 1 1/4" tube will have more fin contact area than two tubes 5/8" tubes because of the loss of contact on the elliptical ends.

I see lots of reports of success with the Champion radiator with 3 rows of 5/8" tubes. The radiators with the 1" tubes seem to be in the $500 range, but they claim to be American made. There are many claims about which radiator is best by materials, construction, etc. I would like to see a objective report about which really is best. Although the original 3 row has a new core, my '55's cooling system is marginal with the AC condenser preheating and restricting the air it gets. Has anyone tried other aftermarket radiators, aluminum or copper/brass, and can report on the effectiveness?