Bubbling Noises
Many bubbling noises are created when air is trapped inside a liquid container
such as the heater core. If this
air is not allowed to exit the system, fluid will trap air causing a bubbling noise
while the system is in operation. Also, depending on the system in question air
can impair the operation of that system. Systems where air can affect the operation
or cause bubbling includes: brake, clutch, steering, transmission, cooling and heater
systems. In this section we will give you instructions on how to check for air in
a particular system. Problems can range from installing a fluid restriction devise
to bleeding the hydraulic
brake system. Below we give answers to common problems to "air in the system"
malfunctions.
Bubbling Noise Air in Brake System - Air can get trapped inside of the brake system due to a leaking brake master, wheel cylinder, brake flex line, caliper or other components such as an ABS controller or proportioning valve. When this condition occurs it can cause bubble sounds when the brake pedal is depressed. To check for this condition check the brake fluid level inside the master cylinder by removing the master cylinder brake fluid cap. If the fluid level is low it can allow air to be forced inside the system producing the bubble like noise. To repair this problem refill the brake fluid and inspect system for leaks or wear. If any leaks exist repair as needed and bleed the brake system.
Brake Master Cylinder
Air in Cooling System - The engine's cooling system used to transfer heat from the engine to the radiator by the cooling system. The radiator removes heat from the coolant by forcing air through the radiator fins. Without coolant your engine will over heat and if left unattended severe engine damage will occur. When your engine over heats it can force coolant into the overflow container which can create a bubbling sound. Never check the coolant level until the engine has cooled completely. If the engine is not overheating air can be trapped or CO2 (exhaust gas) is being generated will cause bubbles in the cooling system. Complications from these bubbles can include: overheating, thermostat operation malfunction and coolant displacement. Once a cooling system is empted sometimes it can be tricky refilling the system. Due to the design of the cooling system air is sometimes naturally trapped inside the system so look for “bleeder” screws on the cooling system components, they are there to let the trapped air out . Sometimes it can take several cycles of the system being hot and cold before air is completely displaced. If once the cooling system has been purged of air the air bubbles return it could be a sign that the head gasket or other engine component has failed. When a CO2 leak first develops it may or may not cause the engine to overheat. For more information check: engine over heats.
Radiator Cap and Coolant Reservoir Air in Heater System - Air in the heater system (core) can be caused by excessive coolant volume being pushed through the core. This heater core is design to have "restricted" coolant flow to minimize bubbling. To repair this condition a flow re-stricter must be installed on either the core input or out hose. Refill cooling system normally, recheck as needed. Air in Clutch System - Some standard transmission car manufacturers use a hydraulic actuation system much like a brake system would use. Like a brake system, a clutch system can exhibit the same bubble noises for the same reasons. Check the fluid level of the clutch primary slave cylinder. If the primary cylinder is low it will cause the system to take in air causing a bubble sound while in operation (pressing the clutch pedal down). There is no reason for a large amount of clutch fluid to disappear like a brake system (A brake system is subject to brake calipers that fill with fluid as the brake pads wear) if the fluid level is down it is because the system is leaking and needs inspection. Repair and bleed the system as needed and recheck system. Air in Power Steering System - The power steering system utilizes hydraulic fluid to transfer force from the power steering pump, the rack and pinion or steering box, without fluid the system cannot function. If the fluid level is low it can pull air into the system causing a whining noise due to the bubbles in the system. Check the power steering fluid level by locating the power steering fluid reservoir and remove the cap (twist counter clockwise). Most systems have a fluid level dip stick mounted inside the cap.
If the fluid level is down or there is no fluid in the reservoir the system has a leak. Inspect the entire power steering system: pump, hoses and rack and pinion or box assembly, replace worn or broken components as needed. Refill system with manufacturers recommended fluids then start engine (hands away from engine) and turn steering from lock to lock several times. Shut the engine off and recheck fluid level, allow system to stand for a period of time to allow air in the fluid (aeration) to dissipate. Check fluid level and re-top as needed.
Power Steering Cap Air in Automatic Transmission Fluid - An automatic transmission functions by automatically changing the gear ratios while determining the speed and load of the engine. A torque converter utilizes transmission fluid as a coupling agent allowing the engine to run while the car is stopped without stalling the engine, then re-engaging to make the car move again once the RPM of the engine has increased. If the transmission is low on fluid due to a leak or service it will cause the transmission to scavenge fluid while taking in air. This air in the fluid can cause a bubbling noise while the dipstick has being removed. Add transmission fluid as needed to obtain the correct level. Check the system for leaks and repair as needed.
Locate and Remove the Transmission Fluid Level Indicator If further assistance is needed, our certified car repair technicians are ready to answer your car questions. Related Car Repair Information
Bubbling Noise Air in Brake System - Air can get trapped inside of the brake system due to a leaking brake master, wheel cylinder, brake flex line, caliper or other components such as an ABS controller or proportioning valve. When this condition occurs it can cause bubble sounds when the brake pedal is depressed. To check for this condition check the brake fluid level inside the master cylinder by removing the master cylinder brake fluid cap. If the fluid level is low it can allow air to be forced inside the system producing the bubble like noise. To repair this problem refill the brake fluid and inspect system for leaks or wear. If any leaks exist repair as needed and bleed the brake system.
Brake Master Cylinder
Air in Cooling System - The engine's cooling system used to transfer heat from the engine to the radiator by the cooling system. The radiator removes heat from the coolant by forcing air through the radiator fins. Without coolant your engine will over heat and if left unattended severe engine damage will occur. When your engine over heats it can force coolant into the overflow container which can create a bubbling sound. Never check the coolant level until the engine has cooled completely. If the engine is not overheating air can be trapped or CO2 (exhaust gas) is being generated will cause bubbles in the cooling system. Complications from these bubbles can include: overheating, thermostat operation malfunction and coolant displacement. Once a cooling system is empted sometimes it can be tricky refilling the system. Due to the design of the cooling system air is sometimes naturally trapped inside the system so look for “bleeder” screws on the cooling system components, they are there to let the trapped air out . Sometimes it can take several cycles of the system being hot and cold before air is completely displaced. If once the cooling system has been purged of air the air bubbles return it could be a sign that the head gasket or other engine component has failed. When a CO2 leak first develops it may or may not cause the engine to overheat. For more information check: engine over heats.
Radiator Cap and Coolant Reservoir Air in Heater System - Air in the heater system (core) can be caused by excessive coolant volume being pushed through the core. This heater core is design to have "restricted" coolant flow to minimize bubbling. To repair this condition a flow re-stricter must be installed on either the core input or out hose. Refill cooling system normally, recheck as needed. Air in Clutch System - Some standard transmission car manufacturers use a hydraulic actuation system much like a brake system would use. Like a brake system, a clutch system can exhibit the same bubble noises for the same reasons. Check the fluid level of the clutch primary slave cylinder. If the primary cylinder is low it will cause the system to take in air causing a bubble sound while in operation (pressing the clutch pedal down). There is no reason for a large amount of clutch fluid to disappear like a brake system (A brake system is subject to brake calipers that fill with fluid as the brake pads wear) if the fluid level is down it is because the system is leaking and needs inspection. Repair and bleed the system as needed and recheck system. Air in Power Steering System - The power steering system utilizes hydraulic fluid to transfer force from the power steering pump, the rack and pinion or steering box, without fluid the system cannot function. If the fluid level is low it can pull air into the system causing a whining noise due to the bubbles in the system. Check the power steering fluid level by locating the power steering fluid reservoir and remove the cap (twist counter clockwise). Most systems have a fluid level dip stick mounted inside the cap.
If the fluid level is down or there is no fluid in the reservoir the system has a leak. Inspect the entire power steering system: pump, hoses and rack and pinion or box assembly, replace worn or broken components as needed. Refill system with manufacturers recommended fluids then start engine (hands away from engine) and turn steering from lock to lock several times. Shut the engine off and recheck fluid level, allow system to stand for a period of time to allow air in the fluid (aeration) to dissipate. Check fluid level and re-top as needed.
Power Steering Cap Air in Automatic Transmission Fluid - An automatic transmission functions by automatically changing the gear ratios while determining the speed and load of the engine. A torque converter utilizes transmission fluid as a coupling agent allowing the engine to run while the car is stopped without stalling the engine, then re-engaging to make the car move again once the RPM of the engine has increased. If the transmission is low on fluid due to a leak or service it will cause the transmission to scavenge fluid while taking in air. This air in the fluid can cause a bubbling noise while the dipstick has being removed. Add transmission fluid as needed to obtain the correct level. Check the system for leaks and repair as needed.
Locate and Remove the Transmission Fluid Level Indicator If further assistance is needed, our certified car repair technicians are ready to answer your car questions. Related Car Repair Information
- Bubbling Noise Questions
- How to Replace a Steering Pump
- How to Fix a Radiator
- How to Replace a Master Cylinder
- Replace Clutch Slave Cylinder
- How to Fix Power Steering Problems