Recently I got my '50 CJ3A chassis running and I took a few trips around my street in triumph. But I noticed a mist coating of coolant on my glasses with each lap! A pressure test revealed some leaks in solder joints but of more concern was a crack in the top tank. Considering that and the appearance of heavy deposits inside, I deemed this to be beyond the realm of a low cost repair. A new direct fit copper/brass replacement goes for around $500 USD which is just too expensive for my budget so as an alternative I looked into the overseas aluminum radiators. These things seem to have proliferated quite a bit on collector cars if you have hit a cruise night in the past 10 years.
Unfortunately, as of early 2016, there is still no direct fit replacement aluminum radiator for �50 � �53 CJ3As with side mount fitment (at least as far as I could determine). A few parts vendors out there claim they have a radiator that will fit CJ3A's, but it appears those units are actually for tall hood Jeeps; they will interfere with the low hood and the top tank inlet requires relocation to avoid fan interference (as described in CarlsJeep post from a few years ago).
I investigated utilizing radiators that have similar dimensions to the Jeep but the swaps I found online had few details on mods required to make them work. So, I decided the best option was to get a CJ2A bottom mount style radiator. Making this unit fit a side mount application seemed like it would require the fewest mods, and could be done using a modest set of common garage equipment (no aluminum welding!)
There are many e-stores selling CJ2A aluminum radiators but I suspect there are probably only two or three actual manufacturers of them. I chose an ebay supplier which listed one for $135 to my door. I was careful to choose one that had a notch in the bottom tank to clear the steering bellcrank bracket (some don't).
I got the unit in about a week and to my critical eye it looks pretty good. It is 3 rows of tubes deep by almost 50 tubes across (many more that the copper brass replacements) and most dimensions are the same or extremely close compared to the old radiator (of course with the exception of having no side flanges.)
I made flanges from 0.094� aluminum sheet in order to match thermal expansion rates of the radiator uprights (thus minimizing stress on the radiator.) I fastened the flanges to the radiator uprights with 8-32 truss head machine screws. There is space under the uprights to drill and tap without hitting the outermost coolant tubes, so I very carefully used a drill stop on my drill bit and put in the holes for 8-32 screws. The uprights are somewhat thin but I felt comfortable that 9 fasteners per side would spread the load adequately. The rear vertical line of holes in each flange double as a mount for the shroud. I added two more holes on each side of the shroud to help spread the load.
I wanted to put the new core in the same position as the old core, but the aluminum radiator bottom tank is �thicker� than the old brass unit and interferes with the curved front crossmember. To accommodate this interference, I moved the new radiator rearward about 5/8� so the bottom tank cleared. There is still plenty of space remaining between the core and the engine fan, but the rearward movement of the shroud engulfed the engine fan which is not ideal: the fan blades should be half in/half out of the shroud opening for best efficiency. To move the shroud forward to it's correct location required trimming about an inch off the bottom (and re-bending the 90 degree flange), and about an 1/8� on the curved beaded top piece. There were other minor snips here and there to help fit it best against the radiator.
For reference, the rear opening of the shroud should be 7.0� from the flange mounting surface of the grille as designed by Willys. (So the radiator fan is half in/half out of the shroud opening.)
One other significant shroud modification involved cutting and contouring the lower left in order to clear the curved lower outlet neck of the new radiator. CJ2A�s used a long, upward curving neck unlike the short straight CJ3A neck. One picture shows the lower hose and the mod to the shroud.
The radiator looked really nice once installed, but I still had to mess around with hoses. I purchased a Dayco 70081 hose which is the �correct� bottom hose for a CJ2A, but the fit is horrible. I ended up purchasing a Dayco 71762 hoping to use a section of it as the bottom hose, but it was still not pretty. I ended up using pieces of both hoses along with a metal union piece in the middle to make a perfectly fitting hose.
I filled up the radiator and fired up the Jeep to check systems: No leaks, and to test the shroud/fan system, I did the paper test (to see if the fan sucks a slip of paper to the core) and it passed. I let the engine idle for 15 minutes and drove it around a bit too. Basically, it would heat up until about 185, then you could tell the thermostat would open and it would cool down to about 170 very quickly. It kept bouncing between those two temperatures....it cools very fast and the thermostat just keeps closing when it cools down.
So that's my report. There are probably plenty of other ways to do this, but I'm glad I kept my 3A shroud, and the installation looks pretty good. I'll take it all apart and smooth and paint the shroud and other stuff when the body work is underway.
