A recurring engine overheating issue can be equal parts terrifying and frustrating. So to help ensure things stay cool—even if you’re blasting the A/C on a scorching summer day—we’ve put together some general tips, techniques, and advice on cooling system performance.

Airflow is Everything

If you’re still in the middle of your build, plan adequate space around the radiator, fan, and fan shroud.

Coolant transfers heat to the tubes, the tubes transfer heat to the fins, and without proper airflow, a radiator is just a reservoir for hot water.

Speaking of airflow, whenever possible, choose an electric fan over a mechanical one. Electric fans deliver maximum airflow independent of engine speed, making them ideal while idling or low-speed cruising.

installing electric cooling fans into a jeep xj Cherokee
(Image/Christopher Campbell)

Fans: Pusher vs. Puller & Mechanical vs. Electric

Puller fans (that pull air through the radiator from behind it) are always preferred over pusher fans (that are placed in front of the radiator and push air through). Mounting a push-style fan in front of the radiator can interfere with airflow at highway speeds.

Select a fan that covers as much of the core surface area as possible; wider cores might require two fans or a fan shroud.

man drilling holes to install a fan shroud on radiator
(Image/Jeff Smith)

Fan shrouds play an essential role in the cooling system: in applications with an engine-driven fan, or
smaller/multiple electric fans, they help funnel air through the entire core for the best efficiency.

Water Pump Pulleys, Caps & Thermostat

Underdrive water pump pulleys can free up drive horsepower, but sometimes compromise water pump efficiency. Overdriving the pump by 30 to 35% or using a high-flow water pump can improve heat exchange through the radiator.

Always use the recommended radiator cap and verify the pressure rating. Each pound of pressure raises the coolant boiling temperature by 3° F—a 16 psi cap raises the boiling point to 260° F.

close up of a radiator cap
(Image/Jim Smart)

It’s essential to run your engine with a thermostat. Engines have a recommended operating temperature range of 180°F to 220°F. Operating your engine at the correct temperature reduces wear, promotes complete combustion, and vaporizes moisture in the crankcase, which gets drawn out by the PCV system.

More Helpful Cooling System Tech Articles

These are some of the common considerations. If you are experiencing cooling issues, we’ve got a handful of articles that can help.

Keywords
cooling system, fans, radiator
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Author: Dave Matthews

Dave Matthews was a mechanic for the U.S. Army, a Ford dealership, and served for many years as a fleet mechanic for construction companies. Now a technical content producer at Summit Racing, Dave has spent decades working on everything from military vehicles to high performance race machines.