As a car owner, it is essential you know the works of the coolant in your car. Coolants are the toxic liquid that goes into your car’s reservoir to keep the engine running at an optimal temperature without blowing up your head gasket.
However, overfilling this liquid has its adversaries. Are you trying to know how much coolant should be in the overflow tank, or you’re asking should there be coolant in the overflow tank at all?
In this article, we’ll discuss at length and even show you the amount of coolant loss that will significantly affect your engine’s performance.
Understanding the Coolant System
Your vehicle’s cooling system regulates engine temperature, preventing it from overheating. It circulates coolant through the engine and radiator, pushed on by the water pump, absorbing excess heat.
The coolant reservoir stores extra fluid for expansion when the engine gets hot and retracts coolant when it cools down.
The coolant reservoir helps to maintain proper coolant levels and preventing pressure build-up. Without it, your engine could overheat or become damaged, and it ensures that your engine stays cool and operates efficiently.
Type of Coolants
As there are many variants of coolants available in the market, you must understand the various coolant types. We strongly suggest you read reviews about coolants’ to make an informed choice.
Let us dive into the different types of coolants.
- Organic Acid Technology (IAT) Coolant: Several brands deal with organic acid technology coolant. It’s widely available in many colors like such as dark green, pink, and orange.
- Inorganic Acid Technology (OAT) Coolant: Mechanics widely used this conventional coolant in older cards. This variant needs to be refilled or changed as it loses its attributes soon.
- Hybrid Organic Acid Technology Coolant: As the name suggests, this coolant is a hybrid of inorganic acid technology and organic acid technology. The majority of new vehicles use it.
Different coolants fulfill different functions.
How a coolant reservoir works?
Many car owners have a general knowledge of how a car works. But do they also know how a coolant reservoir works? A coolant reservoir plays a major role in ensuring your car runs smoothly.
A problem with this component (like no coolant in the radiator) can cause severe damage to your engine system. Therefore, it is recommended that you know the work of a coolant reservoir tank and how to figure out issues with your reservoir tank.
As your engine burns fuel to power your car, it generates a tremendous amount of heat. If this heat gets to a certain level, it causes severe damage, like cracked cylinder walls and blown head gasket to your engine.
This can cause your car to stop at any time. Although these damages can be repairable, it causes you to pay for hours of labor.
Your car’s cooling system’s sole aim is to extract heat, keep your engine at an average temperature, and prevent these types of damages. The cooling system circulates coolant to your engine through a water hose and pipes surrounding your engine.
Thus, the extracted heat from your engine converts it into gas and sends it back to your radiator – converting it back to a liquid form. During this process, the radiator sends the extracted heat outside your car.
As your car’s temperature rises to a certain degree to release pressure, the spring in your radiator cap expands, which in turn, allows your coolant to escape straight to the reservoir tank.
This coolant stays in the reservoir until your engine cools down and requires more coolant from the reservoir tank to continue the circulation.
So, you might ask, how much coolant does my car need when empty? Your coolant reservoir tank should be at least 30% full. Most reservoir tank has a minimum and max mark drawn on the side of the container.
The most common cause of a coolant leak is a bad radiator cap, bad radiator fans, and loose radiator hose clamps.
So, is it normal for the coolant level to drop? Yes, due to the degree of a running engine temperature, a small amount of coolant tends to drop through vapor.
A leak means that the stored coolant is dripping out, which will eventually cause a low coolant level.
To prevent engine overheating, ensure you check your radiator and coolant level regularly. If you notice your temperature gauge is going high while driving, you have to pull over and turn off your car.
And allow your engine temperature to cool down. Check your coolant and inspect if there are any leaks.
Why Does Coolant Reservoir Tank Overflow?
#1. Excessive Coolant Fluid.
The most obvious reason that the tank is overflowing is that you filled it too high. Even if it looks normal with the car engine off, the levels are going to fluctuate once it’s running.
It’s important to keep the levels between the minimum and maximum markings. These indicators leave room for expansion when there is more coolant in the tank.
#2. Bad Radiator Cap.
If the radiator cap gets loose or becomes damaged, the coolant isn’t going to remain where it is supposed to.
The cap is responsible for maintaining a closed system. However, when the cap is bad, pressures get altered, and the engine could easily overheat. An overheating engine leads to excessive amounts of fluid in the tank, causing it to possibly overflow.
Thankfully, it’s not difficult to replace a broken radiator cap. You just have to find the one that’s compatible with your system because it needs to be built for a specific amount of pressure.
#3. Defective Water Pump.
A faulty water pump can slow down or halt the flow of coolant entering the system. When the pump breaks or is damaged, the engine overheats. Not only can this lead to fluid filling up the tank, but it can also create a leak around the pump itself.
The cost to replace a water pump is about $400 to $650. This expense includes both the part and possible labor charges.
#4. Malfunctioning Thermostat.
The thermostat is used to determine how much coolant is required to reduce engine temperature.
If the thermostat is faulty, the engine can’t utilize the right information and cooling might not occur as it should. With the inability to regulate the fluid, the tank could overflow and the engine might overheat.
Thankfully, this replacement is a little less than some of the others. You might spend $150 to $300 to have a new thermostat installed.
#5. Cracked Block or Head.
If you notice boiling liquid or gas bubbles in the overflow tank, there might be a major issue with the engine block or cylinder head. In some cases, it could be due to a blown head gasket, but it could also be a cracked block or head.
Sadly, these issues require major engine repair. In some cases, you might need a new engine installed. You could easily spend thousands of dollars with either a blown head gasket or a cracked block.
#6. Bad Radiator.
The problem could also be coming from a bad radiator. Today’s radiators are often built with a lightweight plastic material, making them less durable than they once were. Older radiators were designed with aluminum and copper for additional durability.
If you have a clogged radiator, it can lead to an excessive amount of fluid in the tank. For the most part, you would spend about $250 to $500 to have a new radiator installed. To prevent further issues, you want to have this vital part replaced at the first sign of wear.
How much coolant should be in the overflow tank?
The coolant reservoir holds the coolant when the fluid heats up while the car runs. The coolant in your reservoir should be the precise quantity needed at every point. Not too little and too much, as both can affect the system and the engine.
When there is not enough coolant, it generates excess heat, which causes the engine to overheat and results in further damage to your engine. On the other hand, you don’t want the coolant reservoir overflowing either.
You might want to stop your vehicle from overheating by edging the coolant on the filler neck. That, too, is wrong and can cause a problem.
Filling the overflow tank above the maximum level would not allow the coolant to expand as it should. If the coolant expands without knowing where to go, it causes the system and the engine.
It is ideal to fill the coolant reservoir to at least 30% of the tank. Two marks on the overflow tanks indicate the minimum and maximum levels.
The minimum mark tells you the lowest amount of coolant your engine needs; anything below that amount may cause overheating problems. The full mark, too, shows the highest amount your engine can handle without any damage.
Since there has to be space in your overflow tank for the coolant to expand correctly, it is advisable to put it slightly above the minimum mark and keep your eyes on it for refilling.
How do I check my engine coolant?
- Make sure the engine is cool. A good rule of thumb is to make sure the engine has been switched off for at least 30 minutes (or longer if you suspect it has overheated).
- Locate the coolant tank. This is always under the hood of your vehicle and is generally connected to the radiator.
- Inspect the coolant level against the ‘min’ and ‘max’ volume indicators on the tank. (A healthy coolant level should be somewhere between the two).
- Top up your coolant as needed (after double-checking that you are using the correct coolant type).
- Use this opportunity to check for leaks or issues with the connected hoses.
- If you have concerns about an unexpected drop in coolant level, the engine overheating/freezing – or issues with the coolant tank itself, take your car to a local garage.
The Benefits of Correct Coolant Levels
Maintaining the correct coolant level offers a range of benefits, including:
- Improved engine performance: Correct coolant levels ensure the engine runs at its optimal temperature, improving performance and efficiency.
- Reduced fuel consumption: Maintaining the correct coolant level can lead to reduced fuel consumption, saving you money on fuel costs.
- Increased engine life: Correct coolant levels can help extend the life of your engine, reducing the need for costly repairs or replacement.
- Reduced emissions: When the engine is running at its optimal temperature, it can lead to reduced emissions, contributing to a cleaner environment.
Diagnosing the Issue
If you’re getting coolant pushing out of the reservoir, it usually indicates a serious concern that needs your attention. Diagnosing it is vital, and signs to watch for include:
- Steam from the engine
- Coolant leaking onto the ground
- An overflowing coolant reservoir
- Rising engine temperatures without apparent overheating
To figure out where the problem is originating requires following a few diagnostic steps.
Step 1: Check the radiator cap
One of the easiest tests to perform is ensuring the radiator cap is opening as it should. It operates like a thermostat, and it should open to vent pressure at 15psi.
Using a cooling system pressure tester, check that the rad cap opens when it’s supposed to, and replace it if it’s faulty.
Step 2: Check the coolant condition
The coolant condition can indicate faults, whether it’s debris floating in the coolant that infers a blockage in the rad or oil in the coolant due to a head gasket leak. It should be clean and full.
Step 3: Inspect the radiator hose temperatures
When the engine is turned off after running to operating temperature, check the upper and lower radiator hoses. Both should be similarly warm to the touch. If one is cool while the other is hot, it indicates a blockage.
Step 4: Check for a head gasket leak
Coolant leaking from the reservoir is obvious, but there could be a leak at the head gasket that’s pushing gases into the cooling system. Perform a compression test to determine if there’s a blown head gasket.
Step 5: Test the thermostat
A stuck thermostat can cause cooling system pressures to build up. You can put the thermostat in a pot of hot water and test what temperature it opens, or simply run the engine and test the temperature going in and coming out of the thermostat housing to see if it’s opening when the engine is hot.
Step 6: Bleed the cooling system
Sometimes, air in the cooling system from a repair can cause coolant to spew from the reservoir under pressure. Find the appropriate procedure for your vehicle to bleed air from the cooling system.
FAQs.
Q: When Should I add coolant to my overflow tank?
If you notice the coolant level is low when cold, you have to too up the coolant. Or notice the car running hot; you have to turn off your engine.
Allow it to cool down. It will take your engine one to two hours to cool down. Once your engine is cool, open your radiator and overflow tank, and top your overflow tank till it gets to the full level. And top your radiator till it gets to the brim.
Q: Should my coolant overflow be empty?
No, if you notice that there is no coolant in the overflow tank, you don’t have to refill it. You have to inspect for coolant leaks with your underhold work light.
Also, inspect the level of coolant in your radiator. Always ensure your radiator is filled to the brim. It is advisable to check your radiator every morning before starting your car.
Q: Can I drive with an empty reservoir tank?
It is not advisable to drive with an empty reservoir tank. If your reservoir tank is empty, your radiator might be low as well since it sends and draws coolant from the reservoir.
Ensure you inspect your water hose, radiator cap, and the radiator itself immediately if you notice an empty reservoir tank.
Final words
The level of coolant to pour into the reservoir tank is just as important as the color and type of coolant you intend to pour into the system.
Always ensure you pour the right amount of coolant into your reservoir tank. I believe by now. You should be able to answer questions like how much coolant should be in the overflow tank and how the engine works.