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One-way or two-way valves allow the movement of liquids through a system according to certain parameters. The coolant check valve helps to maintain the right amount of pressure in the cooling system.



What Is a Coolant Check Valve?

A vehicle’s cooling system must be able to cope with a variety of different situations and temperature conditions, so that it can adjust as needed the flow of liquid through its plumbing system. To do so, it must consider the nature of the coolant itself, which is especially designed to provide maximum protection, but can expand and contract through the temperature range.

The cooling system is effectively sealed, so without a means of releasing pressure it would not be able to deal with the consequences (bursting) when a hot coolant expands. This is why safety mechanisms like the coolant check valve are built into the system.

How Does a Coolant Check Valve Work?

Each manufacturer mandates that a certain volume of coolant is added to their system. In normal operation, this coolant will expand as it gets hotter and this will in turn create an increased amount of pressure within the closed system.

In many vehicles, the pressure relief process begins with the radiator cap which is a device that is designed to hold pressure until it reaches a point. Within the cap is a valve that’s spring-loaded and calibrated very accurately, which will activate and release the pressure by drawing off some coolant into a reserve tank.

There’s a secondary valve called a coolant check valve that is designed to stop this coolant from returning to the system until the pressure has normalized and the system coolant has returned to original temperature. When this happens, the valve opens and “sucks” radiator from the reserve tank back into the system. This will ensure that the primary system is always full and no air is introduced to the system, which in the long term could cause corrosion.

How Is a Coolant Check Valve Made?

This valve is usually made from stainless steel (and sometimes brass), so that it resists corrosion.

How Does a Coolant Check Valve Fail?

  • Becomes clogged with the sediment that may build up in the cooling system

What Are the Symptoms of Failure?

  • Overheating
  • Build up of air in the system
  • Overfull reserve tank when cold

What Are the Consequences of Failure?

  • Radiator failure

Care should be taken to ensure that the indicated coolant levels in the reserve tank are within recommended parameters when the vehicle is cold or hot. Also to make sure that the coolant check valve is operating correctly, to maintain the pressurized system.

If you have questions or concerns about Coolant Check Valves or any of your vehicle’s components, come into your local Pep Boys where we can answer any question, help you find any part, or perform any vehicle service you might need.