Check valves are used in a wide variety of applications and in many different industries. They are designed to allow airflow through a valve in one direction but to prevent any backflow.
A vacuum check valve has the same important role in a system. However, it is designed to provide the seal necessary to allow the vacuum to exist. Without this valve it would be impossible for vacuum components to operate, including components like brakes and air condition systems in vehicles.
Early Signs with Air Flow
One of the early signs of problems with a vacuum check valve may be an issue with the air conditioning or heating system in the vehicle. In these situations, the flow of air may change if the vehicle is being driven or if it is just idling.
The check valve may not be directing the air correctly through the valve, only operating when the engine is at full power, and the pressure in the system is high. There may also be issues with leaks in the hoses or the connection of the hoses to the valve. It is also possible the vacuum pod or the actual vacuum itself.
A vacuum check valve in a brake system can also fail over time. The driver may assume this is many different things including the brake cylinder or simply worn brakes.
The most common early sign of this type of an issue with the valve is a spongy or soft feel to the brake pedal. In some cases, the brakes just seem to take a lot longer to engage even when the pedal is depressed. Without replacing the valve, there is a risk the brakes will fail.
It is also important to check the vacuum brake booster at the same time. If air has been able to get into the lines and through the valve into the booster, it may need to be replaced as well.
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