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Installing Flex-a-lite Radiator, Fans & Fluid Coolers

Posted in How To: Engine on July 18, 2019
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It's big, it's red, it's a Ford, it's Redferd. Our 1978 Ford F-250 has seen many a mile of backroads across this great country of ours, and thus far (at least since we've owned it) Redferd has kept its cool, despite the 460 ci of pushrod V-8 power moving this big old truck down the road and trail. Still, keeping an old 4x4 cool in the desert Southwest is always a chore.

Enter Flex-a-lite, a name you probably recognize from the company's decades in the aftermarket focusing on moving air and shedding heat. To that end, our pals over at Flex-a-lite sent us one of their brand-new Extruded Tube Core Performance Radiators with integrated dual electric fans that is a direct fit for 1966-1979 Ford F-150, F-250, and F-350 trucks. We also received a couple of the company's universal stacked-plate fluid coolers for Redferd's auto transmission and factory power steering system. The installation was super-simple and a great time to address Redferd's old radiator hoses and fan belts for the upcoming Arizona summer. Check it out.

Redferd came to us with what was clearly a rebuilt factory-style bronze/brass radiator. While the outside looked good and lacked any noticeable leaks, the hard water of the Southwest can easily plug up the tubes inside any radiator. We suspect that was an issue because Redferd had approached overheating once or twice on road trips and trail adventures. Thus far, no major damage was done; we just had to sit and wait while Redferd cooled off on the side of the road or trail gurgling and burbling.
Redferd also had what we are betting is either a repurposed factory transmission cooler from another application or possibly a factory original Ford F-250 transmission cooler. Either way, this thing has seen some action. Although it still worked, clearly the mashed fins aren't helping cool the transmission fluid as much as fresh fins would. And as you may know, heat is the main cause of death in automatic transmission land. We have other plans for a remotely mounted Flex-a-lite unit with an integrated fan to keep our C6 nice and cool, come what may.
With the old parts out of the way, we laid out an ogled over the new parts from Flex-a-lite. These new radiators continue to ride on the cutting edge of cooling technology with extruded aluminum tubes that promote heat rejection (cooling your engine's coolant). Also shown is one of the Flex-a-lite Remote Mount Stacked Plate fluid coolers with 3/8-inch hose barb fittings (PN 60002, 9.64x11x3.250 inches) and a Flex-a-lite Stacked Plate fluid cooler with 3/8-inch hose barb fittings (PN 400117, 6x11x0.750 inches). We'll use the remote-mounted unit with the fan for the transmission and the smaller stacked plate cooler for the Ford's power steering system.
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Installation of the new radiator was comically easy. The new unit with integrated fans simply drops behind the radiator core support and is held in place with four factory bolts through the factory mounting points. The extruded tube design is reportedly very strong, and the internal passage volume increases the contact area between the coolant and aluminum tubes (inset A). The extruded tubes also provide a flat, optimum surface on which to braze the cooling fins, cooling fins that have louvers punched in them to direct airflow (inset B). This increase of contact and heat transfer from coolant to tube, tube to fin, and fin to air gives the Flex-a-lite Extruded Tube Core Radiators significantly better cooling capability than is possible with old-style tube cores.

We moved onto building some structure to remotely mount our Stacked Plate fluid cooler. Our plan is to mount the cooler in one of the many open spots under the truck's bed. That should help keep it cool since there are few other sources of heat under the bed (other than the muffler), and this unit has its own fan and thermostat to switch the fan on when the ATF reaches a preset temperature.
Our Extruded Tube Core Performance Radiators with integrated Flex-a-lite dual electric fans comes with a Flex-a-lite Variable Speed Controller (VSC), but little Redferd has its own electric fan control built into the Summit EFI-500 Throttle Body Fuel Injection. So we rounded up three 12-volt relays. Two of the relays will run the fans on the radiator, while the third will run the fan on our remotely mounted Stacked Plate fluid cooler. Wiring up these relays is pretty easy, and we did use the Maxi fuse that was included with the Flex-a-lite radiator to protect the three relays on the power supply side.
We then mounted the relays and Maxi fuse to Redferd's inner fender and tied the supply side into the starter solenoid. The instructions that came with the EFI showed us how to wire the two radiator fan relays so the computer can control them via the ground terminal of the two relays. The third relay is hot running to the small integrated electric thermostat, which turns the fan on and off when needed.
Some folks don't like self-tapping screws, but we sure do. They are quick and easy when mounting lightweight components like this Flex-a-lite Stacked Plate fluid cooler we will run in series of the low-pressure power steering hose. On the other side we used a bit of spare aluminum angle and some 1/4-inch bolts to secure the cooler ahead of the radiator.
We mounted the remote Flex-a-lite Stacked Plate fluid cooler with integrated fan and thermostat under the bed just aft of the bed on the passenger side. We may need to make some mud flaps or dust baffles if we drive Redferd in more mud.
Someone named Jim or John sent yours truly a letter and a nice used factory grille insert for Redferd to replace the not-our-style chrome steel grille insert that Redferd came to us with. Sadly we can't find a return address on the box, and we're not sure what Jim or John's name really is (his signature is like most of ours, and harder to read), but we sure would like to say thanks. We do still have to source the correct screws and plastic retainers for the insert, but you can bet it will go on Redferd as soon as we suss that out.


Fife, WA

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