Why Does My Coolant Reservoir Keeps Emptying?

In cars, the availability of coolant is important to ensure engine cooling. It works to keep the heat of the car at length from the engine; hence the efficiency of the vehicle becomes even more optimal. In short, the coolant in the car makes sure there is no overheating of the engine that can otherwise cause damage.  

But, sometimes the coolant reservoir (expansion tank) keeps emptying. Why does this happen? If you have been a keen driver, there would be times when you question yourself about why my coolant reservoir keeps emptying. This article is all about that.

If the coolant reservoir keeps on emptying, the hose must be damaged, or cracked from somewhere. The hole in the radiator or issue with the water pump is another closely possible reason why the coolant reservoir is not keeping up with the fill-up. Sometimes it can just vaporize into the mist through the defroster!

Now let’s find more information to solve the persistent problem. 

What is a coolant reservoir?

The coolant reservoir in the car or vehicle is there to make sure the engine is not getting heated up. It works as a cooling system in cars. You can easily see near the radiator as a storage container with the clear plastic design.

When the engine works, it releases the heat, so the coolant reservoir in the car absorbs heat to regulate its temperature. That’s it!

In case the coolant level gets minimal, it will automatically top up from the reservoir to ensure the car engine never gets the hike in temperature. 

Read Also: How Long To Run Engine after Adding Coolant

How do I know if the coolant reservoir is empty?

If you are unsure about coolant leakage or how to spot if it’s getting empty, here is how you should find it out.

  1. Low or No Coolant Level- if the coolant in the engine is low, it’s one of the signs why the coolant reservoir is getting empty. To check, open the hood of the car and find out the level of the coolant. If it’s low, top it up.
  2. The leakage in the coolant will certainly empty it. So it is the obvious sign that your coolant reservoir is at zero level. Check out if there is any leakage in the coolant system, if there is any cracks, small hole or damage in the coolant reservoir, immediately get it repaired
  3. If you are unsure if coolant is empty or not, check on the dashboard of your car, if it’s reading high engine temperature, it means the coolant reservoir is now empty. Sometimes it can mean that coolant isn’t circulating adequately. The coolant may also have a hard time in regulating the temperature of the engine.

What happens if you keep driving with the coolant reservoir empty?

If you drive for a few miles, it may not cause any adverse effects. But as you know coolant in cars makes sure the engine is cool and the temperature is under control, so if you drive farther, it can cause damage to the engine. Certainly, if you keep on driving with the overheated engine, you cannot expect no damage and all safety of your vehicle.

How far can I drive with low coolant in the reservoir?

Things become instantly vulnerable when you have low coolant in the reservoirs. If you mean that low coolant is still above the minimum mark, you can drive for a few days. But if it’s below the minimal mark, avoid driving till you get it filled. Otherwise there can be serious engine damage due to overheating.

5 causes of empty coolant reservoir 

If you have the reason for the problem, it becomes easier to solve it. Now when you know that your coolant reservoir is getting emptying, it’s time to know the reason why that’s happening. Here are the 5 causes that empty the coolant reservoir no matter if you have just filled it.

1. Puncture in the radiator

Another reason for emptying the coolant reservoir is the hole in the radiator. Usually, most of the leakage in the fluids happens due to damage in the container. So if the radiator has a hole, there is no doubt why the coolant keeps on emptying in the car engine.

The hole or damage in the radiator can be due to a hard collision of the vehicle or maybe it has come to its durably concerns. Usually, when the radiator has become worn-out due to aging, it will start to degrade which can cause the coolant to pass through the fissures.

2. Water pump seal is faulty

If the water pump seal is faulty, the coolant in the reservoir will leak. For that you should keep a check on regular inspections to satisfactory performance. If there are any cracks, or the pipe has hardened, replace it. However, you should opt to replace the seal as well as the pipe for the best solution. 

We suggest, you take professional assistance in replacing the water pump and its seal because it demands certain tools and technical knowledge.

3. Fault in the head gasket

Another reason for coolant not staying in the reservoir is the fault with the head gasket.

The head gasket is there between the oil return passages, cylinders and pistons, sealing the coolant passage. When it has faults, it prevents those channels from keeping up with the seal, here the coolant in the reservoir starts to leak.

If the head gasket has cracks for whatever reason, it will not let the coolant keep in the reservoir. The coolant will release and the car engine will start to overheat.

4. The coolant hose is leaking

Another reason why coolant is emptying is the leak in its hose. If the hose is leaking you can tighten it with a new bolt or clamp. Replace the hose of the coolant if you find any leakage. Also check the head gasket for any leakage.

5. The radiator cap is damaged

When the radiator cap is damaged, the coolant will not store in the reservoir if the radiator cap is cracked, broken, or it is not fitted correctly, there can be leakage that is emptying the coolant. The broken cap in the coolant reservoir will cause the coolant to evaporate, making the level minimal to zero. Hence, all you see is the empty coolant reservoir even after fill-up.

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