Radiator Upgrade Tames Our Classic Mustang Engine Temps

Classic Mustangs are known for their style and free-spirited driving experience, but they aren’t as much fun when they overheat. Cooling issues are common on these cars, and our 1965 Mustang had a frustrating history of running hot. Eventually, this caught up with us, with the unfortunate result being a blown head gasket. That led us to upgrade the engine’s top-end, but we also had to address the cooling system with a Frostbite radiator and fan upgrade from Holley.

“If you remember, the whole reason why we installed that top-end kit was because I actually blew the head gasket because the car overheated,” Chris Friend, owner of the 1966 Mustang, said. “The truth is, these early Mustangs have always had cooling issues. So, if you look at the Shelby ’65 and ’66 Mustangs, they have a different bumper with a much wider grille to bring in more air to cool the engine better.”

To keep our engine coolant temperatures under control — and our fresh head gaskets in place — we upgraded our 1965 Mustang project with this three-core Frostbite aluminum radiator (PN FB121) from Holley. This lightweight, polished unit features more cooling fins per inch and is engineered to cool engines producing 450 to 750 horsepower, and it also carries a one-year limited warranty. (Photo Credit: Holley)

With the engine repaired and its performance enhanced, we knew we had to get serious about cooling. We elected to install a three-row, aluminum Frostbite radiator (PN FB121) paired with a Scott Drake electric fan and shroud kit (P/N C3DZ-8146-8600A). Designed for the 1965-1966 Mustang, this cooling combination is built to support both reliability and high-performance driving.

“I suspect that this car never cooled right. I tried cheap electric fans, I’ve tried a lot of other things, including bigger radiators, and nothing quite worked right,” Friend admitted. “So to keep this car cool with this extra performance now, I reached out to my friends at Holley, who recommended their three-core Frostbite radiator, and their fan and relay kit.”

We paired the Frostbite radiator with this Scott Drake electric fan shroud kit (P/N C3DZ-8146-8600A) from Holley. Based around a high-performance, 16-inch SPAL electric fan rated at 1,650 cfm, the kit includes a wiring harness, a relay, and an adjustable thermostatic switch.

Case Of Frostbite

This Frostbite radiator is a serious unit. Built from aircraft-quality aluminum, it’s designed to support engines making 450 to 750 horsepower. It’s got a three-row downflow core, with both the inlet and outlet located on the passenger side, making it a straightforward fit for early Mustangs. However, the increased core thickness means the stock mechanical fan wasn’t an option, which is why we turned to the Scott Drake fan and shroud kit for a clean, compact electric solution.

The Scott Drake cooling fan kit features a 16-inch SPAL fan that moves 1,650 cubic feet per minute, housed in a black powder-coated aluminum shroud that mounts flush to the radiator. Integrated flaps allow airflow at highway speeds without relying on the fan. The setup is only 3.25 inches deep, so there’s plenty of clearance for the front-end accessory drive of our 289. The included wiring harness, relay, and thermostatic switch make for an easy install with plug-and-play simplicity.

Designed to fit the 1965-1966 Mustangs, the Frostbite radiator was an easy swap into our classic pony car. Paired with the Scott Drake fan, which is only 3 1/4 inches, there is plenty of clearance between the fan and the front-end accessory drive.

With everything installed, we topped off the system with a 50/50 coolant mix, bled the air, and fired up the engine. During testing, we found the system performed better than expected, even in the kind of taxing environments that used to send the temp needle and our anxiety climbing.

This fetching, polished radiator cap is part of the Frostbite package. It is a 16-pound unit, and it pairs perfectly with the polished radiator top and tanks.

Problem Solved

“The fan came with a temperature sensor that will trigger the fan on at 195 degrees. In my testing with the car, I found it hard to even get there,” Friend added. “It really was, on a hot day with lots of stop-and-go traffic, hard to get that fan to even kick on. So, did we fix the cooling issues in the 1965 Ford Mustang? I would say, yes, we did.”

Drawing just 11 amps, the 16-inch SPAL fan pulls 1,650 cfm of air through the Frostbite radiator, and pass-through flaps at its corners allow more air to pass through at highway speeds.

With our cooling woes handled, we were finally ready to enjoy the added performance from our recently installed small-block Ford top-end kit, which brought new life to our small-block Ford, raising its rear-wheel output to 230 horsepower.

“The AFR top-end kit wonderfully woke up this small block 289…” Friend said. “Which might not sound like a lot, but you have got to remember, in 1965, this car only made 180 at the crank — and we were also limited by our transmission.”

The Scott Drake fan kit includes a wiring harness, relay, and an adjustable thermostatic switch. The switch is designed to engage the fan at 195 degrees.

Now, not only is our Mustang running cooler than ever, but we also have the confidence to fully explore the extra horsepower under the hood without constantly watching the temperature gauge. For any classic Mustang owner looking to solve persistent overheating issues, especially after a performance upgrade, the Frostbite radiator and fan combo is a great solution for those more concerned with performance than concours judging.