Cooling System

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The automotive cooling system has become increasingly important to the overall operation of today’s vehicles.

Not only does the vehicle’s cooling system keep the engine from overheating, it also affects engine performance, fuel consumption (how many miles per gallon the vehicle gets), and even the ability for the vehicle to pass an emissions test. On computer controlled vehicles, the computer constantly gathers temperature data and makes various adjustments to engine operation based on this data. This means that a properly functioning cooling system is critical to the everyday functions of your vehicle.

Fortunately, inspecting and maintaining your vehicle’s cooling system is fairly simple. The main areas of inspection are listed below, along with brief instructions on how to perform the necessary checks. You should perform these checks on a regular basis. Remember, it’s always better to replace parts during mild temperatures than to risk being stranded on the side of the road in hot, unsafe conditions.

BE SURE to let the engine cool COMPLETELY before checking the cooling system. Engine coolant/antifreeze can reach temperatures above 200ºF (93ºC), and can cause serious burns.

Check the drive belts and radiator hoses.

Make a visual check of all drive belts. Look for cracks, splits, fraying edges or glazing. If any of these conditions are noted, replace the belt

Make a visual check of all radiator hoses. Look for cracks, splits, pinholes or bumps. If any of these conditions are noted, replace the belt.

Squeeze each radiator hose. The hose should feel firm, but flexible. Replace any hose that feels brittle or excessively soft.

Check fluid levels (coolant/antifreeze, windshield washer fluid, brake fluid, etc.)

Remove the radiator cap and check that the radiator is filled to the proper level with the correct mixture of water and coolant/antifreeze. Add coolant as needed.

DO NOT add plain water to the radiator except in case of emergency. Plain water will reduce cooling system efficiency, and can cause rusting and early failure of the radiator, water pump and/or engine. Coolant should be replaced in accordance with the manufacturers stated lifespan. Despite retaining its color, coolant can degrade over time and become much less effective than it was originally. An inexpensive tool, called a “hydrometer”, can be purchased at most Auto Parts stores to check the condition of the coolant/antifreeze.

Other fluids, such as windshield washer and brake fluid, are checked by simply looking at the reservoirs and verifying they are correctly filled (see your vehicle’s “Owner’s Manual” for details).

Check the radiator pressure cap

Make a visual check of the radiator cap, spring and gasket. If the gasket is worn, or the spring looks damaged, replace the cap. If the cap appears to be in good condition, have it pressure tested to verify it can hold the required pressure for your vehicle. Replace the cap if it fails the pressure test.

Check the fan and fan blades

For mechanical (engine-driven) fans: Check the fan blades for straightness. Check for cracks or loose rivets. If any damaged is noted, replace the fan immediately.

For electric fans: Make a visual check of the fan blades. Replace the fan if any damage is found. Check the fan operation with the engine running. If the fan fails to activate when appropriate, have it checked by an authorized repair technician.

Check the fan clutch

Make a visual check of the fan clutch for dirt or oil streaks on the clutch housing. If any streaks are noted, replace the fan clutch immediately.

If the fan clutch passes the visual check above, verify that it is operating properly. BE SURE to wear heat protective gloves when performing these checks.

First, check fan’s “stability” by grasping two fan blades opposite each other (such as the 3 o’clock and 9 o’clock positions) and try to shift the fan from side to side. Any movement in excess of ¼-inch (25 mm) indicates a faulty fan clutch. Replace the fan clutch if it fails the “stability” test.

Finally, start and run the engine until it reaches normal operating temperature, then turn the engine off. Using gloves (fan may be hot!) try to spin the fan with only one finger. The fan should turn no more than twice. Replace the fan if more than two rotations are observed.

Check the water pump

Checking the water pump is typically very simple. Look over the entire body of the water pump to locate a small hole (somewhere around the main portion of the pump). Normally, this hole will leak coolant/ antifreeze when the pump needs to be replaced. If the hole is clean and there is no evidence of leaking, the water pump should be in good condition.

Check for internal leaks

Check the coolant/antifreeze for signs of oil. Carefully remove the radiator cap (be sure engine is cool), and make a visual check of the fluid. If a gray, brown, or white slime is in the radiator is observed, a serious problem may be indicated. Have your vehicle inspected immediately if this type of residue is present.

Even if an oil leak is not indicated, you may not be in the clear just yet. Although rare, another form of internal leak, caused by a failed gasket, can allow engine exhaust to make it’s way into the coolant. The easiest way to check for this condition is to have a service technician check the pressure and integrity of your vehicle’s coolant system.

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