Frequently Asked Cooling Questions From - 12/2002

Edited by:Ron Hollatz


What is the function of a radiator?

When a car is driven, the engine generates enough heat to destroy itself. Because of this, your car is equipped with a cooling system to protect against damage and keep the engine within the correct operating temperature range.

The radiator, an integral part of the cooling system, is designed to protect an engine from the destructive forces of too much heat. The radiator's function is to lower the temperature of hot coolant coming from the engine by cooling air that passes through the radiator. A radiator is constructed with two key components: a core made up of small flat tubes, and overflow tanks which are either on the top and bottom of the core or on either side.

Why do you need to know what a radiator is?

Vehicles five years and older are prime candidates for cooling system troubles, troubles that could strike when least expected. An aging vehicle has been exposed over time to environmental factors that can harm a car's cooling system. Salt from ocean air, road salt, debris and other chemicals break down the metal in a radiator core. All these factors can contribute to an overheating vehicle, which could potentially cause a blown engine.

How do I make sure I'm keeping on top of my radiator maintenance?

Knowing basic radiator maintenance is essential knowledge for any vehicle owner. You should periodically drain, flush and refill your cooling system. This replenishes the antifreeze mixture and prevents formation of rust and corrosion, which can cause poor performance and engine damage. When you service the cooling system, check all hoses and the radiator cap and replace them, if necessary. Preventative cooling system maintenance is indispensable in helping to ensure your engine's life

How do four wheel drive conditions affect enigine cooling?

In 4WD situations, greater engine stress puts additional pressure on the radiator. This type of engine stress is a common cause of overheating. The cooling system of a vehicle in 4WD dissipates enough heat to warm two average size houses. Add a warmer climate to the already stressful conditions of four-wheeling and your stock radiator could fail at any time. An upgrade radiator will enable your engine to run at peak performance while reducing the risk of overheating. Many of these upgrade radiators can be installed with little or no modifications to your vehicle, and are made to fit your specific vehicle perfectly.

Important things to remember

Replacing your existing radiator with an upgrade will not necessarily make your engine run cooler, but it will prevent the engine from overheating better than the stock radiator. Most modern engines run best at a fairly high temperature. When the engine is cold, components wear out faster, the engine is less efficient, and the vehicle emits more pollution. So another job of the cooling system is to allow the engine to heat properly and quickly, and then to maintain the engine at a consistent temperature

Also, installation of an upgrade radiator is not the only step in ensuring that your engine is running at proper temperature. Upon replacing or upgrading your radiator you should also have the engine flushed, check the thermostat for proper opening and closing, conduct a visual inspection of all cooling system components including all belts and hoses, and test the engine fan for proper operation.


Problem Symptom What To Do
Insufficient coolant Temperature warning light goes on Check coolant level. Fill to proper level with 50/50 coolant mixture
Dirty or rusty coolant Rust or sediment in coolant sample Flush cooling system. Fill with fresh 50/50 coolant mixture
Hose deterioration Spongy or swollen hoses. Very hard hoses. Hoses swollen or cracked around hose clamps Replace hoses. Replace frozen or bent clamps
Thermostat stuck in open position; opening too soon Heater delivers cool air. Engine heats up too slowly Check thermostat. Replace if hung open or opening too soon
Worn fan belt Cracks or fraying on inside of belt. Car may overheat due to slippage of belt Check fan belt and other drive belts. Replace those that are worn. Check all belts for proper tension
Sludge or rust in radiator Engine overheats. Sludge or rust visible through radiator filler neck Clean Radiator Cleaner. If car is older than 7 years, you may need to replace it
Coolant overflow Coolant overflows through overflow pipe Check pressure cap. Replace if necessary

How to Flush Your Cooling System

Today's engines run much hotter than in years gone by. Added emission control systems, smaller radiators, crowded engine compartments, and smaller grill areas add to the challenge.

Mechanics will recommend that you flush the system every two years, but the folks at recommend you flush your system every year for maximum life.

Flushing The Cooling System:

1. Begin with the engine cold and ignition off. Remove the radiator cap. MAKE SURE THE ENGINE IS COOL. If the radiator cap is too hot to touch, your engine is not cool enough.

2. Open the drain-plug at the bottom of the radiator and drain the coolant into a bucket. You will want to dispose of the cooling fluid as environmentally conscious as possible. Check with your local shops or recycling places in your area to see if they can dispose of it for you.

3. Close the drain-plug and fill the radiator with water.

4. Start the engine and turn the heater control to hot (this will open the heater control valve).

5. Add cooling system cleaner and idle the engine for 30 minutes (or as per the instructions on container).

6. Stop the engine and allow it to cool for five minutes. Drain the system.

7. Close the drain-plug, fill the radiator with water and let the engine idle for five minutes

8. Install new 50/50 mixture of water and ethylene glycol antifreeze/coolant. Be sure you use the same coolant as was in your vehicle

It's that simple! Good luck.

Directions for Measuring a radiator

There are two basic types of radiator design. They are distinguished from one another by the direction of the coolant flow and location of the two tanks. In the downflow radiator, the coolant flows from the top tank downward to the bottom tank. In the crossflow type, the tanks are located at either side, and the coolant flows across the radiator horizontally from tank to tank.

How to measure the radiator core:

Before you measure the size of the radiator, make certain that the radiator is in upright position with the filler-neck opening facing upward, then determine whether it is a down-flow or crossflow type.

When measuring either type, you will actually be measuring the core only. The core is the central part of the radiator (between the tanks and the side pieces) and consists of parallel rows of tubes and fins. MEASURE ONLY THE CORE to determine the size of the radiator.

Cross Flow Radiator Down Flow Radiator
Cross Flow Radiator Down Flow Radiator

A. Core Height
B. Core Width
C. Core Depth
D. Header Depth
E. Header Length

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