Flex-a-Lite Fan Replacement

Keeping an engine cool that has been swapped into a place it never belonged is always a bit of a challenge. Today’s modern aluminum radiators are the way to go and companies like Flex-a-lite, which has been making electric fans for years, can put an entire package together with coolers, temperature sensors, cooler guards and fans to keep everything cool and happy under the hood. Cooling doesn’t just stop at the water in the engine though; trans coolers, engine coolers and, with large tires, even steering coolers all fight for space in your project.

Our LS swap into the CJK8 has all of the above. I wanted to retain the engine oil cooler. I will be running 44-inch tires in the snow with a PSC ram assist steering system, so I wanted a steering cooler in the system, and a 4L80E transmission, so I needed a trans cooler… Now, how to fit all of that behind what is a really narrow CJ grill.

Flex-a-lite does make a swap-in radiator to fit a CJ/YJ/TJ grille area, but I wanted the largest core I could fit. I also wanted dual fans this time as a fail safe, so one fan down there is always a second. To get this in, I needed a wider rad core than the CJ/YJ/TJ LS swap radiator could fit. Then there was fitting in three auxiliary coolers for my accessories.

Flex-a-lite does have the option of custom building a radiator for any application, but in my case, I noticed a ’70-’81 Camaro LS conversion package that would fit into the space I needed and came with the dual fans I was looking for. This package draws up to 3000CFM of air through a large twin one-inch tube rad core via the fully-shrouded S blade fans, and comes with a variable speed controller for the fans. Up front, I got two auxiliary coolers and the radiator also has a built-in trans cooler in the passenger side tank. While a stock truck LS radiator has a long hose that transfers water over to the driver’s side, this radiator has the inlet and the outlet on the same side, making the hose connections much easier in the small space.

Of course, this radiator is much wider than the stock CJ grill would allow, so some modifications were needed to my grill to get this radiator in; keep in mind, this was a personal choice on this one. I run a lot of high speed in the snow and sand, and wanted maximum radiator volume – they do make a direct-fit radiator for many Jeep swaps. There are direct fit JK stock engine and Hemi conversion radiators, and as mentioned, CJ/YJ & TJ conversions for AMC V8, Ford V8, LS and regular GM V8 engines. Along with coolers and spare fans to help cool almost any engine.

As the JK steering gear resides above the frame rail, some serious CJ grill mods had to take place. Of course, if this was a JK front end, that grill is much wider and thinner and has better space. Not to worry, that’s what the cut-off wheel, grinder and welder are for!

As I have a full Holley engine management system, I’ll have the computer take care of turning the fans on and off via a dash bypass switch, so I can turn the fans off for deep water crossings. I’ll have a warning light in line on this switch as well, so I don’t forget to turn the fans back on and wonder why my temps are climbing.

Flex-A-Lite, well known for its cooling fans, has a complete line of radiators and coolers as well. This package with twin fans is designed for an LS swap into a pre-’80 Camaro – but direct-fit Jeep radiators are right on their web site. Why did I pick this model for a Jeep install? I wanted a wider than stock rad and twin fans, and was willing to put the time in to get the large radiator into the rig.

Along with the radiator and fan package, I was in need of some added coolers for the transmission, steering and engine oil. Flex-A-Lite covers all these bases as well, with auxiliary coolers and cooler guards and bracket kits to get everything into your ride.

The cooler and cooler guards, along with the bracket kit, is a nice package that eliminates the need to put those cooler ties through the fins of the rad like most other cooler kits, though if needed they can be mounted that way as well.

The radiator has a transmission oil cooler built in, but I needed a cooler for the engine oil as I planned on using the factory oil cooler lines the engine came with, rather than install a block- off plate which is a popular option. When running big tires, I like a cooler for the steering system as well.

The Flex-A-Lite auxiliary coolers come with a clamp system that goes around the cooling tubes on the ends of the cooler to hold them to the bracket system. Pretty slick set up.

The cooler guards are designed to bolt through these clamps and into the brackets. A small spacer stands the cooler guard slightly off the cooler and the bracket stands the cooler off the radiator for best possible airflow.

I had to make a slight adjustment to the bracket system to get it to fit behind the narrow CJ grille. Typically, you would use the slotted fins on the end tanks to attach the brackets, but I had to go top-to-bottom with the brackets rather than side-to-side. Also, this Camaro conversion rad had most of the cooling fins shaved off the end tanks – which actually worked well for me, as I had a very narrow spot to get the radiator in. I had the brackets tig welded to the top and bottom plates on the rad, which are just tank covers anyway and don’t flow rad water.

The end tanks of the Flex-A-Lite radiators are covered in fins, which also act as mounting locations for brackets. Each bracket kit comes with fasteners with backing plates that slide down into the fins.

Making the grille as thin as I could to get the wider radiator in. I had to make a little trim of the fan shroud where it came in contact with the JK steering box. Again, keep in mind, for a JK swap, Flex-a-lite has a Hemi swap rad ready to go and several versions for the narrower CJ/YJ/TJ grille for engine swaps. These changes were only needed due to my personal desire for twin fans and the wider radiator.

The JK steering gear was pretty close to the shroud, so a little trim was needed. It won’t really hurt cooling, but I made sure down the road I didn’t have a rattle with the steering box hitting the shroud over bumps.

If you look under the hood of a GM truck, you will see a long radiator hose going from the passenger side over the motor to the driver’s side radiator tank. Most conversion radiators for LS transplants change the rad to have the inlet and outlet on the passenger side. This makes for much shorter radiator hoses and better fitment for places V8 engines were not meant to be. The radiator also has a built-in trans cooler.

It’s a snug fit but enough room for the big 3,000CFM fans to clear the engine accessories. If needed, I had room to push the engine back another full inch, but this seemed to work out pretty well. Below is the work I did to the CJ grille to reduce its thickness to accommodate the wide radiator. Typically, the radiator would fit between the headlight buckets. Also note how wide the bumper is to the grille – that’s the width of a stock JK grille.

The hoses end up very close to the rad fittings with this style of radiator, rather than a crossflow design with the inlet on the opposite side of the radiator. There are advantages to having the crossflow style, but in this case, the packaging of the engine and rad work better with both inlet and outlet on the same side.

The wide radiator extended behind the headlight buckets which required further modifications to the CJ grille to push the headlights ahead, rather than being inset like the stock grille has. As mentioned before, Flex-A-Lite does have conversion radiators to work better with the TJ/YJ/CJ grilles – it was a personal choice to make room for a wider radiator to get twin fans in place. Yes, the cardboard covering the rad fins will come off in due time!