Most of us know that our truck's cooling system prevents the engine from overheating, and any of us combustion-engine-equipped driving human beings have witnessed firsthand how much heat can be generated driving down the road. As a matter of fact, during just one minute of operation, a typical cooling system deflects enough heat away from your engine at highway speeds to heat your home for an entire day.
One of the most overlooked systems, the one that most people ignore altogether until it becomes a problem, is the cooling system in their truck. It's a shame. Most think that the cooling systems only function is to protect against heat, but the cooling system really has many other features that benefit the overall performance of the engine. Many people don't even think about how the cooling system helps maintain the proper operating temperature. This lets the combustion chamber properly vaporize the engine's fuel completely, thus improving the engine's efficiency, creating better fuel economy, and reducing harmful emissions. Another key benefit of a healthy cooling system is that it allows your engine's oil to lubricate at a lower viscosity, permitting the oil to penetrate the entire engine and enabling all the moving parts to move freely, while reducing oil drag or parasitic loss, which in turn makes more power.
After time, your truck's cooling system wears down, just like any of the thousands of parts that make up your truck. If overlooked, this can become a big problem. A subpar cooling system can cause failures of other vehicle systems. So if you're driving around a classic truck with a built engine and an old, outdated cooling system, you could be asking for disaster.
| The U.S. Radiator 1/2-ton C-10 radiator is designed specifically to fit the '67 to '70 trucks. This four-row, cross-flow unit is constructed from copper and brass to offer a long service life with maximum cooling efficiency. You can direct-fit the unit to the factory 3 1/2-inch mounts, and it features the same 1 1/2-inch inlet size with a 1 3/4-inch outlet size. Paired with an aluminum shroud made at the U.S. Radiator plant in Vernon, California, it covers the entire core face to pull the airflow through a pair of 11-inch Spal fans, which pull more than 1620-cfm over the 2 5/8-inch-thick radiator core. This low-profile shroud and fan setup only protrudes about 2 5/8 inches past the radiator's core face, allowing more than enough space for all the engine's accessories.
Although there are many items that make up a complete cooling system, the primary components are the radiator and its cooling-fan partner. They handle most of the brunt from the engine's heat. The main function is to exchange hot engine coolant from the engine to an outside heat exchanger (radiator), which is has a series of small tubing that transfers heat to the outside of the vehicle as air travels or passes across the tubing containing the hot fluid. The fins help guide the airflow across the tubing, allowing the heat from the tubes to dissipate to the atmosphere. The coolant fan's main purpose is to simulate the amount of air that would normally pass over the radiator's coolant tubes at highway speeds during low-speed driving. The fan also acts as a backup in high heat conditions, such as climbing a hill—or the killer of them all—stop-and-go traffic.
Let's focus on these two parts of the cooling system during this replacement install: the cooling fan and radiator. And we'll touch on a few other items that make up the recipe for a healthy cooling system in our project C-10.
| First, we replaced the worn out radiator pad mounts on the bottom of the core support with a new set ordered from LMC Truck. These are designed to fit just like the OEM replacements and didn't disappoint.
| The upper radiator pads and mounts are a bolt-on design. Ours were in need of replacement, just like the lower pads. The complete bolt-on replacement mounts were also from LMC Truck.
| Here's a great look at the room we gained by opting for U.S. Radiator's Thin-Line shroud with two 11-inch Spal fans. After we slid the radiator down into the lower mounts, we were pleasantly surprised with the space left.
| We installed the new LMC Truck upper radiator mounts. Two fasteners per side hold the rubber isolated mounts to the top of the core support, holding the radiator in place for good.
| We chose to replace the engine's thermostat to ensure our new cooling system works well. This unit is rated to open at 195 degrees, which will keep our Blueprint Engines 383 right in the proper operating range on the road.
| Topping off the engine side of the cooling system, a brand-new thermostat housing from Spectre Performance will divert the fluids to the radiator.
| As the day moved into night, we still needed to get some hoses to finish off our project. With only the local big-box auto part store open, we had to make a template of the top and bottom path of the inlet and outlet hoses to figure out the length. Using a welding rod (you could use a wire coat hanger, too), we shaped out the path and measured the length. Then we headed over to the auto part store to find a replacement set of hoses.
| Upon our return, we slid the hoses over the thermostat housing and radiator passages.
| Next, we secured the hose ends with old-school-style worm-gear hose clamps.
| Here's a look at the upper radiator hose and mounts into place after all the components were installed.
| The same process was repeated for the lower radiator hose. However, this one was a little trickier than the upper hose. Nevertheless, our welding wire template did the trick.
| We ordered our U.S. Radiator so we could cool the Transtar 700R4 automatic transmission along with the 383 small-block engine using the radiator. Sweet Performance located in Placentia, California, makes an awesome kit that converts the inverted-flare-style cooling line fittings to AN-style fittings. This will allow us to route our cooling lines around high-heat producers, such as the exhaust headers.
| Here's the kit for installing the AN hose. First, we removed the old flare fittings from the transmission and replaced them with the new Sweet Performance AN fittings. They feature a Teflon washer to ensure a tight seal to the transmission case, and the 37-degree AN-style flare is a proven design dating back to WWII!
| If you have ever attempted to install an AN hose, you know they can be a real pain to assemble. We got a helpful tool made by the guys at Koul Tool in Lake Havasu Arizona. This tool can fit the different size AN-hose fittings available, which in our case is for Dash-6 hose.
| First step in putting together the cooling hoses was to drop the AN-hose collar into the Koul Tool capsule and set it into the jaws of our bench top vice.
| We pushed the hose down the funnel end of the Koul tool until the hose bottomed out into the AN fitting.
| Next, we removed the hose now attached to the fitting from the Koul tool and finished off the end of this hose by turning in the swivel side of our AN fitting.
| On the radiator side of the cooling hoses, we used a 90-degree fitting to keep the cooling lines tucked away from any moving accessories. We were pretty excited about switching over to AN fittings once we saw how neatly and cleanly our cooling lines were routed.
| To activate the electric fans from Spal, we paired the fans to Spal's relay and electronic fan controller kit. This allows us to set when the fans will turn on and off based on the engines temperature.
| We were able to hide the fan relays and the properly sized fuse up under the dash and out of sight.
| Since we were working on the cowl and doing wiring, we decided to re-route the battery from the engine compartment to the rear of the truck away from the engine's heat (remember, heat kills batteries). With our No Limit Engineering's battery dropout kit, and this Optima Red Top battery, our cooling fans won't have to worry about having enough power to run.
| We topped off the radiator with Prestone 50/50 coolant mix, making sure to bleed all the air out of the system before we hit the road.
| The last hose we attached was the overflow line to our cool, stainless catch bottle. Last but not least, we installed a 16lb lever release cap from Stant. When pressure builds up in the radiator and it needs to be opened, the pressure release lever allows you to safety vent off built-up pressure. Adding a 16-pound-rated cap creates more pressure inside the radiator, thus raising the boiling point of the coolant and water mix. With our cooling needs met and exceeded, we are very close to having a running C-10 on our hands!