- \n
- Radiator pressure cap<\/strong><\/li>\n\n\n\n
- Overflow tank<\/strong><\/li>\n\n\n\n
- Head gasket<\/strong><\/li>\n\n\n\n
- Water pump<\/strong><\/li>\n<\/ul>\n\n\n\n
Besides leaks in those components, there are other possible reasons as to why this can occur. <\/p>\n\n\n\n
Even if the engine does not overheat, the coolant reservoir boiling over is not a good sign and you shouldn\u2019t ignore it. Let\u2019s look into the details of issues with the coolant and why it can boil, and ways to fix this problem.<\/p>\n\n\n\n
![\"Coolant](\"https:\/\/taxiwiz.com\/wp-content\/uploads\/2023\/10\/Coolant-Reservoir-Boiling-But-Engine-Doesnt-Overheat-Causes-Solutions-1024x683.webp\")
<\/figure>\n\n\n\nHow to Know When Coolant Reservoir is Boiling <\/h2>\n\n\n\n
Although the coolant, also known as antifreeze fluid flows through secure pipes, sometimes air can still enter the system. The fluid itself runs through the pipes at very high pressure. So when air enters the pipes in any way, it disrupts the flow of pressure and leads to bubbles forming. <\/p>\n\n\n\n
Here are some ways you will know that the antifreeze reservoir is bubbling:<\/p>\n\n\n\n
Steam Under the Car Hood <\/h3>\n\n\n\n
When raising your car hood, you\u2019ll notice small droplets of steam underneath it. It will look similar to a pan lid when you\u2019re boiling water on a stove.<\/p>\n\n\n\n
Car Hood very Hot to Touch<\/h3>\n\n\n\n
Along with steam, the car bonnet itself will feel extremely hot when you touch it. But the engine itself won\u2019t overheat at this point.<\/p>\n\n\n\n
Engine Power Decreased<\/h3>\n\n\n\n
You will notice a significant decrease in the power of the engine. While everything else in the car\u2019s functioning might seem fine, the engine\u2019s power will appear to decrease suddenly. <\/p>\n\n\n\n
The Hot Smell from Vents<\/h3>\n\n\n\n
The vents will produce a hot, burning smell. It is unlike the typical fuel-like smell that comes from normal exhaust.<\/p>\n\n\n\n
Boiling Water Sounds Coming from the Engine<\/h3>\n\n\n\n
The engine block will become hot and this causes the oil to get thin in consistency. As it is heated up, the oil starts to boil and it will sound like boiling water coming from the engine.<\/p>\n\n\n\n
Reasons for Coolant Reservoir Boiling Without Engine Overheating<\/h2>\n\n\n\n
Here are the common reasons why your car\u2019s coolant reservoir is boiling. But while doing so, the engine remains at a normal temperature \u2013<\/p>\n\n\n\n
1. Head Gasket Leaking<\/h3>\n\n\n\n
Apart from locking the firing pressure on the cylinder, the head gasket also protects the coolant and oil from leaking into it. <\/p>\n\n\n\n
If there is a leak in the head gasket, the hot gases from the cylinders will go right into the water jacket. As a result, the air gets pushed into the coolant reservoir.<\/p>\n\n\n\n
Here\u2019s how you can detect a leaking head gasket \u2013<\/strong><\/p>\n\n\n\n
- \n
- The car is overheated<\/li>\n\n\n\n
- Coolant levels have gone down<\/li>\n\n\n\n
- White smoke released from the tailpipe<\/li>\n<\/ul>\n\n\n\n
2. Low or Contaminated Antifreeze\/coolant<\/h3>\n\n\n\n
After a certain amount of time, the antifreeze will lose its ability to provide enough coolness to counter the car\u2019s heat. <\/p>\n\n\n\n
This is because after driving many miles, the liquid will absorb the car\u2019s engine heat and fail to provide a lower temperature.<\/p>\n\n\n\n
The coolant will then become hot and will boil over the reservoir. Antifreeze can also get contaminated over time if it is old and through leakages in pipes which in turn causes bubbling in its reservoir. <\/p>\n\n\n\n
3. Damaged Radiator Pressure Cap<\/h3>\n\n\n\n
The radiator cap acts to secure the pressure within the cooling pipes. <\/p>\n\n\n\n
While the cap is on tightly, the coolant can easily flow into the expansion reservoir. But when there is something wrong with the cap, air will enter the cooling system and cause boiling in the reservoir. <\/p>\n\n\n\n
When the radiator pressure cap is faulty, there will also be \u2013<\/p>\n\n\n\n
- \n
- The leak of the coolant<\/li>\n\n\n\n
- Uneven distribution of pressure in the cooling system<\/li>\n\n\n\n
- Collapsed radiator pipe<\/li>\n<\/ul>\n\n\n\n
4. Faulty Radiator Fan<\/h3>\n\n\n\n
Your car\u2019s radiator fan plays a crucial role in cooling down the coolant fluid. The fan is connected to the radiator directly by a set of wires. After prolonged periods, the wires can corrode and weaken, causing a malfunctioning fan.<\/p>\n\n\n\n
If the radiator fan isn\u2019t working properly, the radiator will overheat, and the heat will transfer over to the cooling system and cause bubbling. Some indications of a faulty radiator fan include a poor relay, broken wires, and a blown fuse.<\/p>\n\n\n\n
5. Defective Thermostat<\/h3>\n\n\n\n
When the thermostat malfunctions, the temperature can no longer be regulated within the car\u2019s cooling system and engine. As a result, the coolant reservoir will also get heated and then start to boil. <\/p>\n\n\n\n
6. Failing Water Pump<\/h3>\n\n\n\n
The water pump will likely fail if there is a faulty head gasket and leaky pipes. The heat from the gasket will transfer over to the water pump, and it can no longer work efficiently to cool down the engine. <\/p>\n\n\n\n
Consequently, the coolant reservoir will start to boil. <\/p>\n\n\n\n
- Overflow tank<\/strong><\/li>\n\n\n\n