How this system works:
Hearing a bubbling or gurgling sound means that there’s fluid at work. The most common source of this sound is your coolant system, particularly if you have an expansion tank attached to your radiator.
These systems work a little differently than those on other vehicles. In a basic coolant system, the coolant is locked into the radiator, with nowhere to go as it heats. In a vehicle with an expansion tank, engineers have taken into account the natural expansion of fluid when it’s heated.
Your expansion tank is connected to the radiator, usually by a hose through the radiator cap, but sometimes in another location. As the coolant heats and expands, some of it spills over into the overflow tank. When the coolant cools and condenses, it moves into the radiator. Both of these can cause a gurgling or bubbling sound, and are completely normal.
However, there’s also the possibility that there is air trapped in the system. As the bubbles move with the flow of coolant, you hear the movement as a “gurgling”. This can be a problem – air trapped in the system can cause your car to overheat.
Common reasons for this to happen:
- Inexpert Coolant Service: The most common reason for air to be trapped in your system is that it wasn’t bled out properly when your coolant was changed. There are several ways to bleed air from the coolant system, including using a funnel on the radiator attached to a special tool that allows mechanics to run the engine while filling the coolant. There are also bleeder valves located on the coolant lines (notably at the back of the engine) that let you bleed air out.
- Blown Head Gasket: A blown head gasket can allow exhaust gases to enter the coolant, which becomes trapped in the system and can cause a bubbling or gurgling sound during operation. If this is the case, you may also notice that your engine doesn’t run as well as it used to because it’s losing compression due to the leak.
- Air in the Heater Core: Your car’s heater core uses coolant to provide the heat for your cabin. If air makes it into the heater core, you’ll hear a bubbling or gurgling sound from the passenger side, behind the glovebox.
- Low Coolant: If your coolant is low, then air moves in to fill the void left by the missing coolant. Again, this creates air pockets in your system, which cause the gurgling sound. Low coolant is generally caused by a leak or several leaks, including from cracked hoses, a leaking water pump gasket and many other possible locations.
- Normal Operation: As mentioned above, some vehicles have an expansion tank as part of the coolant system, and hearing some bubbling/gurgling is normal with these types of systems.
What to expect:
One of our highly trained mechanics will come to your home or office to inspect your radiator, coolant level and listen to the gurgling noise. The mechanic will then provide a detailed inspection report that includes the scope and cost of the necessary repairs.
How it’s done:
The mechanic will check the coolant level, as well as the condition of the radiator, radiator hoses, coolant reservoir/overflow tank and more. It may be necessary to test drive the car in order to get the engine up to normal operating temperature and duplicate the noise in question.
How important is this service?
While bubbling or gurgling from the engine may be normal on some vehicles, it is not on all of them. It could be a sign of air trapped in the system, which can cause the engine to overheat. Having your coolant system regularly serviced and properly maintained is essential, and one of our professional mechanics can inspect the system and provide any needed repairs.