Project F-Word is our 1969 Ford F100 pickup that we’ve been building over this past year, and it’s getting very close to nearing the finish line. We have the engine in and the fuel system and wiring are all done. But one of the non-glamorous parts of any build is the cooling system, which requires more thought with a Coyote swap than with a simple 302 pushrod or FE engine conversion. The radiator hose routing and sizes are different with the Coyote, which initially had us scratching our heads in contemplation. Then, we reached out to Matt Dawson at Champion Cooling Systems, who is all too familiar with late model engine swaps and happily worked with us to figure out what needed to be done.
Talking to Matt, he offered to reconfigure Champion’s 3-row radiator designed for the ’65-’74 F100 to work with our Coyote. At this time, there was not a bolt-in radiator on the market that you can use with a Coyote swap without building some custom radiator hoses. Because this swap is exploding in popularity, we were determined to work with Champion to bring a radiator to the market that’s an easy drop-in for those enthusiasts doing this at home—in other words for guys like us.
Keep It Simple
Figuring out how to physically bolt in the radiator was easy—Champion Cooling Systems and others have that down pat—but like we said, the hoses are a complication. The stock F100 radiator has a 1 3/4-inch hose for the inlet and a 2-inch for the outlet, so step one was to get Champion to change the inlet and outlet on the new radiator, which they gladly did. This was much easier than fabricating “adapters” from aluminum tubing and multiple hoses. The goal was to keep this as simple as possible, and after talking to Matt it is now.
A few things to consider when picking a radiator. Most people’s initial thoughts are to make it as big as possible. This seems logical to think that it’ll cool an engine better. You eventually reach a point of diminishing return: while a huge radiator is generally more effective at cooling, a bigger radiator carries more water and coolant and there’s no need to carry additional water weight if it’s not adding anything to cooling efficiency. Our performance plans for the truck involve some open track and autocross action, so weight is a heavy concern.
Of course, with any radiator, you must use a fan to circulate air through the radiator in order to keep it cool, so Champion also set us up with a twin-fan and shroud arrangement, but since ours was being custom-built, it was left up to us on how we should configure the actual setup in our truck. We’ll show you that procedure in the photo captions below since it’s easier that way. Matt confirmed that Champion’s 3-row radiator (part #433B) with their dual 12-inch paddle fans would be perfect for our combination.
Also, Coyote engines come with a “degas” bottle that lets the cooling system pull water in and out of the bottle based on engine temperature. This is used instead of a coolant overflow and needs some explanation if you’re new to the concept. The difference between coolant overflow tanks and an expansion tank is that older cars and trucks (like our ’69 F100) had a tube from the radiator filler neck that vented coolant to the ground as it heated up and expanded. If you’re an environmentalist you’re no doubt shuddering reading that, but remember this was years before anyone really cared about the environment.
The coolant would expand with heat, and a vented radiator cap would open slightly and allow the resultant steam to vent. If it just held in the system, problems would occur, like possibly a blown radiator or an overheating situation. This process was good for the radiator but bad for the environment. Adding a reservoir to that vent tube allowed the steam to be expelled, but also allowed for the coolant that came with it to be captured instead of just being dumped on the ground.
Capturing that expelled coolant meant it could then be recovered and reintroduced back into the radiator upon demand. Different manufacturers called them different things: overflow to catch the overflow from the radiator; and reservoir to store the captured coolant; or recovery tank to recover coolant that was expelled when the pressure increased. Coolant can then be returned back to the radiator because the combination of the reduced steam pressure allows atmospheric pressure to push coolant from the tank back into the radiator through the vented radiator cap. This, in turn, adds more coolant to your system and helps to keep the engine a little cooler.
Many plastic tanks have a ‘cold’ and ‘hot’ mark; those marks indicate where the coolant should be in the tank during cold cycles (non-running) and hot cycles (engine running). It’s really just a guide, however, filling the reservoir during cold cycles just means that you will likely end up with coolant on the ground. For this reason, overflow/reservoirs/recovery tanks have their own vent. Expelled coolant will enter the tank from the bottom, and when the level rises it will expel through the vent tube. A system with an overflow will have a vented radiator cap, and usually a sealed reservoir cap. The reservoir is never under steam pressure, which allows the coolant to return via atmospheric pressure.
Some manufacturers and websites will confuse the overflow reservoir for the expansion tank, but the two perform very different functions. An expansion tank works in much the same manner as the overflow tank but serves a very different purpose. Expansion tanks are just that: tanks that provide expansion of your cooling system, giving you up to a half-gallon more coolant. You’ve seen these on some classic cars, like the Galaxie, or even the old Shelby Cobras. But where an expansion tank really differs is that it is typically a sealed system, not affected by atmospheric pressure. As temperatures and pressures increase, the expansion tank allows the cooling system to expand without bleeding any off to the atmosphere.
With this type of system, if the radiator has a cap it will be a non-vented cap; the expansion tank will have the vented cap in case the pressure exceeds the expansion tank’s capacity. In this case, a catch can or overflow can be used with the expansion tank to recapture expelled coolant. Once the system balances out, you should not have to add additional coolant. The expansion tank also has a connection to the cooling system through a by-pass or a heater hose. Therefore, instead of only containing expanded coolant, the expansion tank is actually a part of the complete cooling system and coolant circulates through the tank as it does through the radiator. It’s typically the highest point in the cooling system.
One thing that must be mentioned is controlling the electric radiator fans. The Ford Performance Control Pack has a signal wire from the computer that we used to control the fans based on the coolant temp. It was as simple as grounding the fans and connecting that one orange wire coming from the Control pack.
All Wrapped Up
It’s been quite the journey, and we’re not quite done yet, but almost there with Project F-Word. If you missed any stories, be sure to check out the project vehicle page. Our ’69 F100 has grown up so fast and it’s already been to a few events. If you’ve got questions on this build or would like to see more, please let us know. In the meantime, as a wise man once said: “it’s time to make the donuts.”