How Long Can You Run an Engine Without Coolant?

Car engines produce fire in the combustion chamber when the engine is running, and that is what generates the power that drives the vehicle. Of course, fire generates excessive heat and engine coolant is what keeps the hotness in check.

Think of driving without an engine coolant like this. You want to boil water, you turn on the gas and set the pot on fire without pouring water into it. The pot will become excessively hot and burn within a few minutes. So, if you are wondering how long can you run an engine without coolant, don’t even think of it. It could put you in real danger.

No coolant in car symptoms

What is engine coolant?

Engine coolant, or antifreeze, is a liquid used to keep the engine temperature in check and prevent it from overheating. It is usually 50% propylene glycol or ethylene glycol and 50% water, with other functional additives for lubrication and corrosion protection.

The engine coolant has a high boiling point and operates at high temperatures. As a result, it absorbs the heat from the engine and sends it away through the car radiator fins. Aside from preventing engine overheating, the antifreeze in the coolant prevents the water from freezing at cold temperatures.

Can you start a car without coolant? Will the engine coolant is an essential fluid, it doesn’t stop you from starting the car. However, do not drive without it for any reason.

How long can you run an engine without coolant?

There’s never a situation where driving without engine coolant is advisable. This is because any car without coolant will stop functioning within minutes. And if the car continues running without engine coolant, it will cause catastrophic damages that will require engine replacement.

Why? The car radiator pumps coolant to and through the engine to absorb the excessive heat it generates. The coolant travels through the cylinder heads, engine block, and around the combustion chambers to keep the engine at normal temperature.

But when there’s no coolant in the engine to do this important job, the engine temperature will rise, rise, and rise until, eventually the metal engine components starts to melt. With the amount of fire and excess heat in the combustion chamber, driving without coolant is a surefire way to destroy your car engine.

If you are wondering, no coolant in car but not overheating, stop the vehicle the moment you notice this situation. The only reason for this is that there’s no single coolant in the coolant reservoir and the engine. The coolant temp sensor only reads the hotness of the coolant to know when the engine is overheating. When there’s no coolant to read, the temperature needle will stay normal but the engine bay will be hotter than usual. If you are asking, is it okay to run an engine without coolant, now you know.

Causes of Coolant Loss

You can lose coolant for several reasons. One of the primary causes of loss of coolant is leaks. However, leaks can occur in different areas of the cooling system.

You have a damaged water pump

The water pump serves a simple purpose—it circulates coolant throughout the engine and cooling system. Like every other mechanical component, the water pump can become faulty and cause coolant leaks. If the pump fails to properly circulate coolant to the entire cooling system, it will cause engine overheating.

You have a Cracked coolant reservoir tank

The coolant reservoir is a plastic container that holds excess coolant and returns it back to the radiator when needed. It connects to the radiator through a small rubber hose on top of the radiator.

Many things, such as age and wear, overheating, expansion and contraction, and poor maintenance, can cause the reservoir tank to crack and leak coolant. Also, coolant can also leak from the hose that connects the reservoir tank to the radiator.

You have a faulty radiator

The radiator is an essential cooling system component that cools down hot coolant from the engine and sends cool one to keep the engine running at an average temperature. If the radiator becomes faulty or clogged, you may get debris and sediments inside, which could lead to leaks.

The radiator hoses can become brittle due to age and lead to coolant leaks. If that happens, the engine temperature will rise and cause overheating.

 You have a leaky radiator cap

The radiator cap is not just a cover—it keeps the radiator at the right temperature—as the coolant builds up pressure as it travels back and forth from the radiator to the engine. If the radiator cap rubber seal becomes weak or damaged, it will let coolant leak out.

You have a blown head gasket

The head gasket is a sealant that sits between the head cylinder and the engine block. If it blows, you may not notice it until after some days or even weeks. It endures hot and cold temperature changes.

If the head gasket blows, it will allow the engine oil and coolant to mix, which is dangerous as it could cause further engine damage. Coolant loss due to blown head gasket, will not disappear into thin air. Instead, it’ll leak into the crankcase.

No coolant in car but not overheating

How to Detect Low or No Coolant

To prevent your car from damage due to low coolant levels, you need to know no coolant in car symptoms and how to check the coolant levels. If you notice a sweet fruity smell, your heater system is malfunctioning, your temperature gauge rising to the red zone, or you notice a high fuel consumption, check your coolant level. While these are the signs of low coolant levels, some other things could be the culprit.

To determine if you have a low coolant level, park your vehicle and allow it to cool down completely. When cold, open the radiator and check if it is filled with coolant. Next, check the coolant reservoir, and the coolant should be at the “max” line or close to it. If the radiator is not filled to the brim or the reservoir is not at or close to the “max” line, you have low coolant.

The reservoir tank is a translucent plastic container—you don’t have to open it to check the coolant levels. You can see the coolant level without opening it.

Note: The radiator and coolant reservoir tank build pressure when hot. If you don’t allow it to completely cool down before opening it, the pressure inside could splash hot coolant and burn off your skin.

How to Prevent Coolant Loss

The cooling system in your car needs adequate coolant to work effectively. Here are the most important ways you can prevent coolant loss in your car;

Regular inspection

The most common way of preventing coolant loss is by regularly inspecting the cooling system components. My best practice is to check the coolant level every morning before starting my car and occasionally check the radiator, radiator cap, hose, thermostat housing, water pump, and reservoir for any sign of coolant leaks.

Fix leaks or cracks immediately

No matter how small a coolant leak may be, fix it the moment you notice it. Minor coolant leaks will gradually expand lead to potential engine damage if not fixed on time.

Use pressure tester

Pressure test the cooling system if you suspect a gradual coolant loss but can’t figure out where the coolant is leaking from. When pressure testing, the system exposes any weak connections and lets you identify invisible leaks.

Avoid extreme temperature

Keep an eye on the temperature gauge while driving, especially when towing and during hot weather to know when there’s overheating. While coolant loss is the common cause of overheating, several other things can cause it. When a vehicle overheats, it can lead to expansion, contractions, and cracks in the cooling systems, which will cause a loss of coolant.

Also, change or flush the coolant at regular intervals to avoid extreme engine temperatures and prevent coolant loss.

Final words

To sum it up, you will no longer ask, what happens if I run my car without coolant? Driving without engine coolant, even for a few minutes, is a surefire way of sending your engine to the junkyard. It is better safe than sorry. So, to be on the safer side, always check your coolant level every morning before starting your engine.

Osuagwu Solomon

Osuagwu Solomon is a certified mechanic with over a decade of experience in the mechanic garage, and he has over five years of experience in the writing industry. He started writing automotive articles to share his garage experience with car enthusiasts and armature mechanics. If he is not in the garage fixing challenging mechanical problems, he is writing automotive repair guides, buyer’s guides, and car and tools comparisons.

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