FSJ Jeep Radiator in Rambler

Okay, I'm putting the good three core J-10 six cylinder radiator I have in my 63 Classic... finally! The standard six cylinder two core radiator cooled the 4.6L stroker I had in it and the hopped up 4.0L I now have just fine, stays around 180-190 degrees. That is until I turn on the AC. Then temp comes up to 200-205 until outside temps start getting around 92-95 -- then it wants to creep up to 210-215, and will continue to slowly creeping up. This happens even going down the highway at speed, so it's not an air flow issue. Takes longer for the temp to creep up when going over 45 mph, so it's definitely a capacity issue. Turn the AC off and temp gradually goes back down. SO... I can't use AC in the two hottest months here in SC, July and August... right when you want/need it most! Been needing to do this, just don't drive the car so much any more so have been putting it off.

Here is a comparison of the two. The 63 Rambler radiator is on the left, 74 J-10 on the right. The Rambler radiator was re-cored around 1993, and it was tested and isn't plugged up. The J-10 radiator is a bit more of an unknown, but came out of a parts truck that was running well when pulled. Guess I'll find out how good it is.


That is a 1996 Taurus two speed 15" fan on the Rambler radiator. Notable differences are that the J-10 radiator core is about 1" taller than the Rambler. The bottom tank is also different, but that's mainly because it has a transmission cooler in it. I'm not going to use the cooler. The radiator came out of a manual trans truck and the trans cooler has never been used. It always had plugs in it so should be okay, but I'm not going to risk getting coolant or rust in my trans. It could be leaking inside , haven't checked it. My trans has been working fine for 13 years with just an external cooler, so I'm going to leave it alone. The lower tank is about an inch taller though, which was an issue. The drain is visible on the right side of the Rambler tank, the drain on the Jeep tank is on the bottom of the tank. I removed the trans cooler plugs and drain to test fit on the Rambler because the Rambler has a "pan" under the radiator. This "pan" is on top of the lower radiator support/crossmember, which is about 2.5" tall.

This pic illustrates the difference in core thickness. The tanks are the same thickness on both radiators.  Rambler core is first. It's easy to see there is room for another core:



The Jeep three core takes up that "extra" room:




Edited by farna - Jul/09/2023 at 8:44am

That 15" Taurus electric fan has been great! I've run it since sometime in 2000 with no issues. It's the two speed fan, I think from a 1995 (pre "jellybean") V-6 model. The Taurus those years came with a 3.0L or a 3.8L V-6. I don't know for sure if the two speed fan was used on just the larger engine or not, but the single speed fan doesn't move as much air. I always ran the fan on just the high speed. A two speed controller or two separate thermostats with different cut-on temps would be nice and I was considering it, but since I had to change the radiator the issue became moot -- there is no room between the radiator and fan motor for the Taurus fan! I had to cut the Taurus shroud down a bit to fit it to the stock two core radiator and only have about 3/8" clearance between the water pump pulley bolts and fan motor. The Jeep radiator core is about 1/2" thicker than the stock one, and I can't move the radiator forward because of the grille and AC condensor. The condensor is right against the grille as it is. The 64-66 Classic grilles are flat and have a bit more room, but the upper radiator support and hood latch assembly would then be the issue. Since the radiator can't be moved I had to find a different electric fan solution. I considered switching to a Grand Cherokee/Wrangler water pump and using an aftermarket fan, but this is a "reverse rotation" water pump/fan. If Flex-A-Lite made a reverse rotation 15"-16" nylon flex fan I'd have tried it, but all reverse fans I could find are the standard type metal flex fans, and I didn't want the noise or the gas mileage and power drain.  Not only that but I think the curve of the blades would require more space than I have.

Here's a photo of the Taurus fan with the Jeep radiator in place. If I just had another 3/8" I'd have 1/8" between fan and motor... which is still to close for comfort!



My solution was to order a pair of 12" aftermarket fans. After careful shopping I ordered a pair from Amazon.  Here's the link:
http://www.amazon.com/gp/product/B00MJO4G2I?psc=1&redirect=true&ref_=oh_aui_detailpage_o01_s00

I plan on using a second adjustable thermostat so that the first fan comes on (also comes on with the AC) at about 180-190 and the second comes on at 195-200, or just a few seconds later on a hot day. That will prevent a big power draw all at once. These fans draw 7.5A running, but will draw about 12A on start-up. That Taurus fan draws about 20-30A running and about 40-50A on start.

The pair of 12s should work fine. The 15" fan draws air over 177 square inches. A single 12" (they actually measure 11.5", that's the number I used for my calculations) covers 104 square inches, so I have more radiator coverage with 208 square inches. As long as those fans flow 1500 or more cfm (max rating is 1750, but that might be with no resistance in front) I should be fine on hot days with AC in town, and hopefully stuck in traffic. As long as temp stays under 210-215 I'm okay with it. Won't boil over until about 240 with a 16 psi radiator cap, and as long as it's not boiling over it's still cooling.

You can see a pic of the Taurus fan on the radiator in the first post. The shroud helps, so it does a bit better than a 15" fan alone. Remember though, I said I had to cut the shroud down for it to fit! The fan was only about 1/4" from the radiator, so the shroud probably didn't do a whole lot... may have actually hurt by blocking a bit of air flow.  Here's a couple pics comparing a single 12" to the Taurus fan and the pair of 12". The pair will just fit across the radiator core.





Hopefully I'll finish installing tomorrow, at least with one thermostat. I need to get a second relay to operate the second thermostat and fan.

If the dual 12" aftermarket fans don't draw enough air I'm going to try a 95-00 V-6 Ford Contour dual fan setup. Six-cylinder 99-02 Mercury Cougars and Mystiques also utilize the same fan. Some four-cylinder models use the dual-fan, but most fours were supplied with a single fan.Here's a pic of the Contour setup:


I'm not sure of the thickness of the Contour setup, but it's supposedly thinner than the Taurus fan. The Taurus fan has been quoted as drawing 40-50A on startup and about 25-30A running on high speed. I've been using a 30A relay and a 30A fuse with no issues though (did burn out a relay once, but it was an old relay from the 1988 Comanche I got my original 4.0L from), so it doesn't draw over 30A long enough to blow a fuse. The Contour fans supposedly draw around 30A on startup and 20A running. Stepping them as I intend would keep the initial surge down.

The Contour shroud fully covers a 24.5" wide radiator core, the same width as the AMC core. Height is about the same as well. I had to trim the Taurus shroud down to fit due to thickness, may have to do the same with the Contour. I will have a little more room at the water pump pulley because the dual fans aren't as thick in the center though, so it might work. MIGHT is why I decided to try a pair of 12" aftermarket fans first.


Edited by farna - Jul/09/2023 at 8:53am

Most AMC/FSJ radiator cores are 24-24.5" wide, at least for the six cylinders. One J-10 V-8 radiator I found says the core is 25-7/8" wide, but I think that's including the mounting flanges -- may not though. A couple sites give the overall and core dimensions as the same.

Look closer at the pic and you will see that the water pump pulley bolts stick out the same as the t-stat housing. The shroud/fan assembly mounts just low enough to go under the t-stat housing, but fan motor sits right in the middle in front of the water pump. If I'd pulled the radiator out I might have had 1/16" between the pump bolts and fan. If 1/8" for sure I might have risked running it, but it might be 3/32" at the most... not enough for comfort!

I'm a bit skeptical about the pair of inexpensive 12" fans being enough with AC, but with the added capacity of the larger radiator and the greater coverage they might be okay.  The Taurus fan is supposed to move up to 4500 CFM on high speed, though some sites say 3200, so with 3300 CFM I might be down a little, but then cover more radiator and the radiator is bigger now. Many 90s Volvo fans are supposedly the same motor as the Taurus but thinner, so they may be an option. There are other junk yard options too -- Ford Contour duals, and post 97 Chrysler LS cars have a dual setup also. Getting a factory fan thin enough is my  biggest issue!

http://www.pirate4x4.com/forum/general-4x4-discussion/1034031-whats-better-than-ford-taurus-fan-taurus-fan-better-application.html

Found this for wiring, might go that way:
http://www.nastyz28.com/forum/showthread.php?t=200028

Right now I have a pair of adjustable temp sensors that I plan on using. They use a radiator core probe. Had mine mounted vertical on the outside of the radiator (engine side).  I think I'm going to stick the probes in the cooling fins for a more accurate reading this time.


Edited by farna - Jul/09/2023 at 8:40am

I've been running the Contour fan dual fan for several years with A/C and have had no issues with cooling. I use a Flexolite variable speed controller on it. I ran the stock radiator for a summer with the electric fans and it did OK but switched it out for an aluminum 3 row the following year since my original was in pretty rough shape and I didn't trust it to last.

farna wrote: A pusher setup like you show is a lot less efficient than pulling through the radiator. So maybe there is some hope for what I'm running...

You bet there is hope. The pusher setup was a last resort so we went with the highest CFM rated fans available from BeCool that fit the space. The good news with the pusher setup was the monster sized electric motors and the fancy chromed covers fit in the space. So all in all I would say we lucked out. One other thing that may have helped with that project was the owner requested that Evans waterless coolant be used. That may have given us an additional advantage.