Low Coolant Symptoms, Reasons, and Repair Techniques

Low coolant symptoms include puddles under the vehicle, a sweet smell, and poor heater and engine performance. The symptoms appear due to external leakages, problems with the head and inlet gaskets, or engine mishaps.

Low Coolant Symptoms

You can fix some of these issues by spending a few dollars, while others can be heavy on the pocket. Read on to find all causes, symptoms, and fixes.

Why Does Your Car Have Low Coolant Symptoms?

Your car has low coolant symptoms because of external or internal leakages. These include damage to cooling system parts such as hoses and pumps or defects in the intake or head gasket. Overheating engines and defective radiator lids can also reduce the coolant amount in the reservoir.

  • External Leakage of the Coolant in Vehicle

External leakage in a vehicle causes a loss of coolant and is the most common reason. The good news is that you can easily detect external leaks. The coolant puddle forms under the car, indicating low coolant levels. The coolant passes through several external cooling parts before entering the main engine cylinder block. These leakages may occur in any cooling part, such as the water pump, thermostat, or radiator.

The following problems can cause a coolant leak:

  • The coolant passes through hoses that wear out over time because they get brittle and crack. The hoses get damaged due to chemical and heat exposure or physical impact.
  • Having an old radiator or a corroded one can cause leakage. The coolant passes through the radiator, as it is one of the most critical cooling components.
  • The water pump may get damaged and develop leaks. Since it pumps the coolant, it will leak in case of a worn gasket, seal, or bearing.
  • The reservoir or overflow tank collects excess coolant and releases it into the cooling system when needed. The coolant can leak externally if the reservoir develops cracks, leaks, or faulty seals.
  • Coolant leaks can occur at various links in the cooling system, such as fittings, hose clamps, or seals. Coolant can leak externally if these connections become loose or deteriorate.
  • Freeze, expansion, or core plugs are metal plugs that seal off openings in the engine block and cylinder head. In icy conditions, if the coolant freezes and expands, it can cause the freeze plugs to develop leaks or pop out, resulting in coolant leakage.


  • Low Coolant Due To Defective Intake Manifold Gasket

The intake or inlet manifolds have coolant channels to cool down the intake air. The inlet manifold and engine cylinder block have a gasket separating them and ensuring a proper seal for the manifold. When the gasket becomes defective or leaky, the coolant escapes from the cooling system and enters the inlet manifold.


When the gasket starts to leak, it causes the engine to suck and combust the car coolant. It happens because the manifold distributes the air-fuel mixture to the engine cylinders.
The coolant gets mixed with hot air and drawn in by the engine. You can detect this problem if you see white smoke from the exhaust.

Moreover, the inlet manifold is also close to oil passages in some engines. The coolant can leak into the passages if the gasket leaks, causing the coolant to contaminate the engine oil. It can result in decreased lubrication properties of the oil and potential engine damage.

You will notice the following low coolant symptoms:

  • Engine heating and damage to the internal components such as pistons, valves, and cylinder heads
  • The engine displays poor performance, reduced fuel efficiency, and misfires
  • Temperature gauge reading or warning light on the dashboard
  • Contamination of the coolant with engine oil
  • White exhaust gas
  • A sweet smell


  • Leakage Due To Damaged Head Gasket

A blown head gasket also explains a low coolant amount. The head seal or gasket provides compression and supplies coolant and oil. When the gasket damages or blows, the coolant mixes with compression and burns inside the combustion chamber.

Causes of Low Engine Coolant

Most cars indicate this problem by glowing the check engine light on the dashboard. Additionally, you will notice white or gray smoke coming out of the exhaust pipe.

The gasket may blow due to the following reasons:

  • The gasket may blow due to overheating of the engine. The gasket warps and destroys the seal between the cylinder head and the engine block.
  • Preignition damages the gasket. It happens when the air-fuel mixture in the burning chamber ignites prematurely. It creates intense pressure spikes that damage the gasket.
  • The gasket gets damaged by excessive stress or strain on the engine. It happens when the engine has high RPMs, or you drive aggressively. The increased pressure on the engine can cause the head gasket to weaken or blow out.


  • Evaporation Through Broken Radiator Cap

The radiator lid or cap maintains a specific pressure within the cooling system. This pressure raises the boiling point of the coolant and assures efficient heat transfer. However, if the lid gets damaged, it may fail to maintain the required force.

Consequently, the engine coolant boils at a lower temperature and forms steam. The car will experience a loss of coolant as it evaporates. So if you are wondering, “Why is my coolant low but no leaks?”, the answer may be a damaged radiator lid.

The cap incorporates a pressure relief valve that escapes excess pressure from the cooling system. The pressure relief valve may malfunction in case of a faulty radiator cap. When the excess pressure cannot escape, coolant is forced out of the overflow tube and expelled from the system. It also results in a decrease in the coolant level. You will notice a rising temperature gauge on the dashboard because the coolant will fail to lower the engine temperature.

Moreover, the cap is a seal that prevents air from entering the cooling system. A damaged cap fails to seal properly, allowing air to enter the system. Air pockets in the cooling system hinder proper circulation, leading to localized coolant areas.

  • Evaporating Coolant Due to Engine Overheating

If your car’s engine has a problem that causes it to overheat, you will notice reduced coolant levels. Usually, the engine coolant boils and evaporates from the cooling system. People ask questions like “Can low coolant cause car to shake?” or “Can low coolant cause rough idle?” Low coolant causes inadequate cooling of the engine.

It leads to engine overheating and causes the car to shake or vibrate. An overheated engine does not run smoothly, so you will experience rough idling, shaking, and vibrations. Moreover, the damaged engine leads to high fuel consumption and affects the car’s fuel economy.

Although the coolant withstands high temperatures, it can reach its boiling point when the engine heats. The heat causes the engine coolant to boil, turning into white steam. It leads to air pockets inside the cooling system, restricting the ability to cool the engine effectively.

The coolant is lost due to overheating because it escapes the overflow tube when boiling. Additionally, it causes coolant loss due to damaged hoses, gaskets, or other cooling components. Coolant loss worsens the overheating issue and also decreases the coolant level.

As the coolant boils, the steam increases the pressure in the cooling system. The raised pressure stresses different cooling system components, such as the radiator and pump. The pressure can cause coolant to discharge or rupture a weak part in severe cases.

  • Coolant Sensor Defects

The coolant level sensor detects the level of coolant in the cooling system and reports the information to the ECU. If the sensor is defective, there is a possibility that it will send false signals to the ECU. As a result, the car shows a low coolant warning. The sensor stops working when there are signs of corrosion.

The sensor and its wires get corroded over time since it is always in contact with the coolant and other chemicals. Moreover, if the sensor comes in contact with contaminated coolant, the chances of its damage increase. Dirt or debris in the coolant can disrupt the normal function of the sensor and cause it to produce false signals.

  • A Malfunctioning Exhaust Gas Recirculation Cooler

You should worry about this problem only if your car has an EGR cooler because they are present in only some vehicles. The damaged cooler results in a loss of coolant when it leaks into the exhaust pipe.

You can suspect this issue if whitish smoke comes from the exhaust pipe.

The cooler may get damaged due to the following reasons:

  • Carbon buildup restricting the flow of exhaust gasses reduces the effectiveness of the EGR cooler. The cooler shows decreased performance and potential damage.
  • Continuous exposure to heat causes thermal stress on the EGR cooler. It leads to cracks and leaks that reduce the coolant amount.
  • Contaminated coolant corrodes or clogs the EGR cooler.

If you are wondering, “How long can I drive with low coolant?” or “How long can you drive with low coolant light on?” you might be able to drive the car for a while, yet we do not recommend it. Low coolant means your car’s engine risks overheating and damage. Severe damage can fail the engine and leave you stranded on the road waiting to be towed.

How To Fix a Vehicle With a Low Engine Coolant Level?

To fix a vehicle with a low engine coolant level, start by observing the reservoir and filling the coolant up to the maximum mark. Replace the radiator lid if it seems damaged. Moreover, you can detect and fix the leakage point with sealants or replace the component.

  • Check and Fill the Coolant to the Accurate Level

A common question is can you drive your car without coolant in the winter? People believe that coolant only has a role in cooling the heated components of a vehicle. It’s a misconception because it prevents the water in the cooling system from freezing in the winter season.

If you consider finding a solution for your car’s low coolant problem, you must be sure of the actual level. For that, you can locate the coolant reservoir in your vehicle. Consulting the user manual can help you find it, but usually, it lies close to the radiator.

Fix a Low Coolant on Vehicle

If the coolant level lies between the minimum and maximum marks when your car’s engine is cold, you do not have a problem. If it lies below the minimum label, you must fill the reservoir.

Fill the coolant when the engine is cold by finding the radiator and opening its cap. Fill a good quality coolant till it reaches the maximum label and close the lid. It would be best if you also inspected the radiator’s cap. Replace it if it looks damaged. These caps come for around $5 to $20.

  • Fix Leakage Points and Replace Faulty Components

Fixing the leakage depends on the damage location and the specific faulty part. Therefore, the first step should be identifying the leakage source. If you notice wet spots under the vehicle, there might be a problem with the radiator, hoses, pump, or gaskets.

Check all these components one at a time, and if you find loose connections, like clamps or fittings, tighten them. You can do it easily by using a wrench or pliers. Although you should adequately pull them, ensure you do not overtighten them because that can cause further leakage.

If you detect a problem with the hoses, for instance, if they have cracks or look deteriorated, the only solution is to replace them. You can remove the hoses by removing the hose clamps and installing new ones of the appropriate size. Leakage through the gaskets is repairable. Many gasket repair kits in the market will help you repair the leaks. Otherwise, you can buy sealants to fill the cracks.

Moreover, small cracks or leakages sometimes lead to no antifreeze in car just water. You can patch these spots with epoxy, available only for mending cooling systems. It will keep the system intact until you get the part replaced.

However, you should consult a professional if you notice an issue with the sensor or the engine. They will help you detect the root cause of coolant reduction and suggest repair methods.

Driving with Low Coolant

What Are the Symptoms and Repair Techniques for Low Coolant in a BMW?

Low coolant in a BMW can lead to serious issues if not addressed promptly. The symptoms include a bmw coolant light appearing on the dashboard, overheating engine, and lack of cabin heat. To repair this, check for leaks in the system, replace damaged hoses, and ensure the coolant levels are adequate. Proper maintenance is crucial to prevent costly repairs. Stay informed about bmw coolant light causes and solutions to keep your vehicle in optimal condition.

Can Low Coolant Cause Bad Battery Terminal Symptoms?

Low coolant levels can cause overheating, which indirectly affects the battery. However, it doesn’t directly cause bad battery terminal symptoms. If you’re experiencing such symptoms, like difficulty starting or a weak charge, it’s likely due to an issue with the battery itself or the terminals needing cleaning or repair.


Now that you know the symptoms, causes, and repair methods for low coolant issues, you can take one step forward to implement them.

Here is a summary mentioning the key points from the article:

  • Coolant quantity may drop due to internal (engine, gaskets, sensor) or external (pump, hose, radiator) leakages.
  • You can detect these issues if you notice wet spots under the car or the temperature gauge shows high reading.
  • Filling the coolant in the reservoir, replacing the radiator lid, and fixing small and large leakages will restore the cooling system.

Ignoring coolant issues puts vehicles at significant risk and causes more expensive problems. Therefore, you should take quick measures and eliminate the problem immediately.

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