How do you diagnose a bad check valve?

Author: Wallace Kuhlman  |  Last update: Thursday, November 20, 2025

The signs of a failing swing check valve are often audible. When the disc opens and closes repeatedly (because of low-pressure flow) or violently (because of water hammer), it emits a tapping or hammering sound, respectively.

How do I tell if my check valve is bad?

Symptoms of a Failing Check Valve

For example, failing check valves will start to vibrate and even lose some internal parts when problems begin to arise. Other symptoms of check valve failure include reverse flow and excessive component wear and damage. Check valves will also emit noises as they start to break down.

How do you know if you need a new check valve?

Signs It Might Be Time For an Early Replacement
  1. Water hammer: You hear a tapping or hammering sound, or the pipes are vibrating.
  2. There is leaking coming from anywhere on the valve, even as small as a pinhole or as big as a full-flow spray.
  3. It doesn't pass annual testing.
  4. Your water pressure is lower than normal.

How do you inspect a check valve?

You'll need to take the valve out and disassemble it to look for debris and scratches. Wash all the parts with hydraulic fluid or whatever fluid is used in your pipe system. Check the housing for corrosion, damage or a rough surface. Buffing can help take care of rough surfaces.

What happens when a vacuum check valve goes bad?

Brakes Stop Working

The worst-case scenario occurs when the vacuum brake booster check valve completely breaks and eventually leads to a brake system failure.

How to Diagnose and Replace a Bad Check Valve

How do you test a vacuum check valve?

An easy way to test the operation of the check valve is to disconnect the hose from the brake booster with the engine off (See Image 2). If you hear a whooshing sound when you disconnect the hose, this is an indicator that the check valve is working.

Should a check valve be on suction or discharge?

A check valve will be used commonly on the discharge of the pump to prevent backflow from the downstream system, when the pump shuts off. Check valves are also used to prevent contaminated media in branches from flowing back into the main trunk line.

What are three basic methods of testing a check valve?

Critical check valves are inspected/tested using three main methods: externally, internally and, in unique situations, in-line function testing.

How often should a check valve be replaced?

While some check valves may last for many years without needing replacement, others may require more frequent maintenance or replacement due to wear and tear, corrosion, or failure.

Can a check valve get stuck open?

Fluid movement in check valves can cause debris to build up, making the valve stuck open or closed. Irregular maintenance contributes to debris buildup, and high-speed debris in the fluid can damage internal valve parts.

What is the life expectancy of a check valve?

A metal disc pivots on a hinge or trunnion to prevent reverse flow. Most larger-scale check valves use this design due to their simplicity. With a life span of five to seven years, these valves are often a component that needs to be replaced frequently.

How can you tell if you have a bad valve?

5 Signs You're Having Valve Train Issues
  • Blue smoke is coming out of the tailpipe. This can be caused when a worn valve allows oil to leak into the combustion chamber.
  • Engine is “missing” while idling. ...
  • Engine is backfiring. ...
  • There is a “clatter” in your engine. ...
  • There is a rattling or “tapping” sound in the engine.

How to tell if a well is dry or pump bad?

Is Your Water Well Going Dry? Here Are Some Common Warning Signs
  1. Change in Taste of Water. ...
  2. Well Water Appears Muddy. ...
  3. Water Pumps Running for Longer Periods. ...
  4. Faltering of Faucets Leading to Leakage. ...
  5. Change in Water Quality. ...
  6. Bubbles of the Dissolved Gases Appear in Well. ...
  7. Huge Increase in Power/Electricity Bill.

How do you know if a valve needs to be replaced?

Is it time to replace your shower valve?
  1. Dripping or Leaking. A leaking shower valve is one of the more common signs that it could need to be replaced. ...
  2. Low Water Pressure. ...
  3. Inconsistent Water Temperature. ...
  4. Difficulty Turning the Valve. ...
  5. Age of the Valve.

Can you fix a check valve?

If there is damage to the valve's body, such as severe rust or corrosion, the valve needs to be replaced. However, if damage or wear is only found on internal parts, it's possible to replace the parts rather than the entire valve.

Do check valves get clogged?

If you notice that your shower isn't dispersing hot or cold water, it may mean that your shower check valves are clogged. This video will show you how to clean them and restore the performance of your shower. For more home advice, please visit our help center: https://support.signat...

What are the symptoms of a bad check valve?

Common check valve problems include noise (water hammer), vibration/chattering, reverse flow, sticking, leakage, missing internals, component wear or damage. However, it is worth mentioning that normally the real cause is the wrong size, spring, and/or style for the check valve application.

How much does it cost to replace a check valve?

Costs to replace a check valve

The cost to replace a check valve varies widely depending on the type of check valve, location, and service type. On average, expect to pay between $100 and $400 for a professionally installed replacement check valve. On the other hand, the valve itself costs $35 to $600.

What is the difference between a backflow and a check valve?

Backflow occurs when pressure changes in pipes cause the flow of liquids, gas, or semisolids to reverse in the wrong direction. Check valves are designed to ensure substances in a pipe only flow one way, automatically closing to prevent unwanted backflow if the direction is reversed.

Can you pressure test a check valve?

Typically the check valve is designed for and can therefore be specified for a specific cracking pressure. One way to test cracking pressure is to do a simple air pressure test. It estimates the cracking pressure of a spring loaded check valve.

When would a faulty check valve damage a pump motor?

Reverse flow occurs when water flows upstream of the check valve. This can be extremely costly and dangerous when it occurs at the pump discharge, causing the pump to spin backwards, which damages the pump over time. Prevent this problem by ensuring your valve is working correctly (fast-closing and tight shutoff).

How do you tell if a check valve is open or closed?

Determine the Direction of Flow: Check valves are made for one-way flow. Find the valve body's arrow or flow direction indicator. Verify Flow Direction: Verify that the fluid is moving in the direction the arrow indicates. This attests to the check valve's open position.

How close to pump should check valve be?

The most suitable location for a sump pump check valve is between 8″ up from the pumps discharge to approximately 12″ above floor level.

Should check valve be horizontal or vertical?

Not all styles of check valves function properly or are suitable for vertical flow directions. When installing a check valve, a horizontal line is always preferred, because it takes gravity out of the equation. However, in real-world applications, the ideal situation is not always available.

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