The Flex-A-Lite flex fan is quiet, with a soft whine, and is very effective.
Outside of engine-driven clutch fans, electric fans are the most efficient. The downside is having to create a dedicated circuit for them via the ignition switch. The key element with electric fans is getting the airflow needed to keep the radiator cool. If you install an electric fan, wire it with a relay and thermostat via the ignition switch so it comes on as needed with the ignition on. This eliminates the risk of leaving the fan on and running the battery dead.
When you're choosing a fan, don't forget to use a shroud. Not all Mustang fans were shrouded. However, when the fan is properly spaced, shrouding improves airflow velocity through the radiator at slow or no speed. Watch out for proper fan depth, which is halfway into the shroud for maximum effectiveness.
This is another type of flex fan from Flex-A-Lite.
Oil Is A Coolant
Did you know engine oil isn't just for lubrication? Engine oil cools where it counts--at moving parts, carrying excessive heat away from critical parts like bearings, piston skirts, and cylinder walls. As oil travels over these high-temp surfaces, it's your engine's front-line defense against overheating. Main and rod-bearing temperatures can rise as high as 400 degrees F, which makes coolant temperature pale by comparison. Whatever your coolant temperature is, add at least 100 degrees for the oil temperature. This is why we suggest the use of synthetic engine oils like Mobil 1, Redline, Royal Purple, and Castrol Syntex. These oils stick around when conventional oils begin to break down.
Antifreeze And Coolant Additives
The marketplace overwhelms us with choices when it comes to antifreeze and coolant additives. For years, conventional ethylene glycol antifreeze and water was used to keep our engines happy. Today, there are all kinds of antifreeze types, including water and antifreeze already mixed in one-gallon bottles. There are also environmentally friendly antifreezes designed to keep things safe for ground water and pets. Prestone offers a long-term antifreeze that lasts five years. There are antifreezes designed for severe-duty applications. Cruise the Internet and you'll find all of them.
This six-blade fan is common with add-on air-conditioner packages. However, it's noisy and not as efficient as a flex fan. | 
Did you know the four-blade 289 High Performance cooling fan is available from Tony D. Branda Shelby & Mustang Parts? It's authentic in every way and works like a champ. We like the powdercoat finish. |
Flex-A-Lite has an extensive line of electric fans for classic and late-model Mustangs. Twin fans are good for crossflow and wide radiators. Single fans, like this one, are good for the lighter-duty Mustang operation. | 
Fan depth inside a shroud is important to cooling. Go too deep and you lose effectiveness. Make sure the fan is half inside the shroud, with half of the blades showing. |
Cylinder-head gaskets in all applications must be installed with the end passages at the rear of the block. "Front" means front in all instances. | 
Compression height can and will affect engine temperature. Confirm compression ratio anytime you're building an engine. A miscalculation can bite you because you're unaware there's too much compression. Check this out during the building process, even with engine kits. |
Air-conditioning condensers are one of the biggest overheating culprits because they get hot during use, which causes warmer airflow into the radiator. Make sure your radiator is up to the task if your car has air conditioning. | 
A blown head gasket did this damage to a problematic 289. Symptoms were overheating and sluggish performance. |
Additives like Water Wetter and Hy-per Lube Super Coolant improve the effectiveness of your engine's coolant. Add a bottle and watch engine temperature go down. It also helps prevent corrosion. | |
Likely the most revolutionary antifreeze is from Evans Cooling. Evans NPG antifreeze is expensive at nearly $30 a gallon, but worth every penny if you want foolproof corrosion protection and maximum cooling effectiveness. The Evans nonaqueous coolant requires no water--you run 100 percent of the stuff in your Mustang's cooling system. Expect to use at least two gallons for most Mustang applications. Your Mustang's cooling system must be completely void of water before servicing with Evans coolant, which offers a corrosion-free environment, a higher boiling point (369 degrees F), and a lower freezing point. It also conducts heat better than any coolant in the marketplace. Using it is foolproof if you follow the directions.
If Evans NPG seems like an unnecessary investment, consider this: It never has to be replaced, and cooling system flushing and servicing never has to be performed. A radiator should last the life of the vehicle with Evans inside. Evans NPG has been tested to last 500,000 miles in diesel trucks. After more than 500,000 miles, it was tested and proven to show no chemical deterioration. Consider it an investment you make once. Install it and forget it.
Water wetter additives improve the heat conductivity of your coolant. All it takes is one bottle to improve cooling-system function (when everything is working as it should).
Reasons Engines Overheat - Engines overheat for all kinds of reasons, both inside and outside the cooling system, including:
- Cylinder-head gaskets installed backwards
- Crumpled or pinched exhaust pipes
- Improper ignition timing
- Any airflow restriction in front of the radiator (such as a dirty air-conditioning condenser)
- Lower radiator hose missing the anti-collapse spring (overheating happens when you hit the freeway, and goes away when you get off)
- Belt slippage (yes, it happens)
- Improper water-pump-pulley sizing
- Blocked cooling-system passages (corrosion, gasket sealer, stop-leak, and so on)
- Improper fan for application (such as a reverse-rotation fan installed in error or fan installed backwards)
- Improper valve timing (cam sprocket installed improperly)
- Improper engine building clearances (too tight)
- Fuel mixture extremely lean (carburetor jetting)
- Blown cylinder-head gasket (especially with unexplainable coolant loss)
- Coolant in the engine oil