Fluids: Engine Coolant (Antifreeze)

What it Does

Engine coolant absorbs heat from the engine and transfers it to the radiator for temperature control. It provides freeze protection and corrosion protection.

Why This Matters

Maintaining proper engine temperature is important for longevity and beneficial to both clean and efficient engine operation (regarding emissions and fuel mileage). Freeze protection is necessary to prevent physical component damage. Corrosion protection is important for cooling system health and good heat output in the cabin.

Possible Problems and Concerns

Glycol Concentration:

Engine coolant should be mixed in the the proper concentration (50/50 or so) with distilled water. This provides protection both against freezing temperatures and fluid boiling.

Hidden Overheating:

Concentrated engine coolant does not absorb heat as well as water does. Running straight or over-dosed antifreeze in a cooling system can result in an engine that runs hot (at least in localized areas) without the coolant temperature gauge showing an overheat .This can result in costly mechanical damage to the engine.

Failed Corrosion Protection:

Engine coolant is in constant contact with metal engine and cooling system components. Once the coolant loses its ability to protect against corrosion, rust can develop in the cooling system. This rust can inhibit cooling system flow and contribute to engine overheating in severe cases.

Weakened Plastic:

Beyond modern metal and plastic radiators, many cooling systems contain other plastic cooling system components as well. Degraded coolant can attack and soften plastic. This can lead to fluid leakage and overheating.

Wrong Coolant Type:

Some vehicle specs call for silicate-bearing coolant and other specs forbid it. Some systems are more prone to cavitation than others and not all coolants resist cavitation equally. Coolant is used in lubricating water pump seals – some of which are intended for silicate-bearing coolant and others which aren’t. Coolants should be selected carefully in accordance with cooling system design and specifications; to do otherwise can be costly.

Air Intrusion

Lacking service technique and defective radiator caps can result in air intrusion into the cooling system. This inevitably results in oxidation of the coolant and the corresponding risk of system corrosion.

False Confidence

Regulator radiator cap tests do not test the upper cap seal or check valve. It’s more cost effective to replace the radiator cap on a maintenance basis than it is to fully test it. Ignoring the cap risks intrusion of air into the cooling system and the problems this can bring.

Over-used Coolant:

In short, coolant has a finite lifespan, or at least a finite desirable lifespan. It will continue to cool the engine even when it’s rough shape. But over-used coolant can be oxidized or shift too high or too low in its PH. All of these can contribute to cooling system troubles including corrosion and leakage.