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6 Bad Valve Symptoms to Look Out For

KB Delta is an expert in understanding compressor valves and compressor valve parts. Unfortunately, there are several bad valve symptoms that you have to be wary of to ensure that you are not working with faulty valve stem seals.

Steel Valves, Oil and Gas Valves in Industrial Zone - KB Delta

A proper valve seal will save the thousands of dollars that might be spent to get a valve replacement in the long run. That being so, the saved expenses begin with knowing what the bad valve symptoms are to keep a potential valve fault at bay for a long time.

We’ll be outlining some of these signs and symptoms you should be on the lookout for to maintain the proper functioning of your system.


What Are Valves?

Valves are components that regulate or control the flow of fluids by opening, closing or creating a partial obstruction to various passageways

They are used in industrial processes, including water & sewage processing, processing of oil, gas & petroleum, chemical & plastic manufacturing, mining, and power generation, amongst others. For instance, air valves, play a crucial role in sewage treatment systems because they expel air from the pump column and the force main to improve flow efficiency and reduce surges. Choosing valves for wastewater applications is similar to choosing pumps in that the solids content of the flow media must be taken into account. If the valves get damaged somehow, it could cause a number of issues with the processing system, including pipe bursts, machinery damage, and so on. Consequently, repairing or replacing the valves may necessitate the assistance of Water Damage Restoration Experts.

Likewise, these components come with seals that can be used in different types of engines as well to control oil consumption and valve lubrication.

The different types of valve seals are:

  • Stem seals
  • Valve discs
  • Stem packing
  • Valve packing
  • Ball valve seats
  • Globe valve discs
  • Valve stem packing

Also, the seal’s design and its manufacturing process help to ensure its performance and longevity.


Functions of Valve Seals

A valve’s purpose is to regulate the quantity of air and fuel mixture entering the cylinders for combustion.

These valves have sleeves or guides that help to prevent combustion gases from escaping and mixing with the fuel. The combustion gas chamber is pressurized, and as such, its content is always looking for routes to escape to after every cycle.

Likewise, valves have seals on top of them, which disallows the leakage of oil in the cover into the main engine.

On the other hand, these valve seals are made from heavy-duty rubber, and they are positioned over the valve’s top. A wear down of these seals is evident in the number of signs and symptoms they project.


Bad Valve Symptoms - KB Delta


Bad Valve Symptoms and Signs

The symptoms of bad valves include:

1. Cold Engine

A cold engine test will give you a good idea if your valve seal is faulty.

Here’s how to check:

  • After your car has been left outdoors overnight, and on checking the top of the cylinder’s head inside the valve cover, you notice that there is residual oil on it, then it is a sign that you have a worn valve stem seal.
  • Similarly, when the engine is on, the residual oil is sucked down through the bad seal into the combustion area – As a result, a blueish smoke emerges from the tailpipe.

These bad valve symptoms show that your valve needs replacement to ensure it does not lead to other problems.

2. Off-Throttle Braking

Engine braking involves employing different means to slow down your car asides from the external braking.

In throttle braking, for instance, you can ascertain if the valve is faulty, especially while descending from a steep downgrade where the accelerator pedal remains static.

If a high intake manifold vacuum has already been created and there is a downward slant of the engine, it will cause the oil to accumulate at the front of the valve cover over the head. What’s more, burned oil will tend to exit the tailpipe in large amounts when the accelerator is pushed after a long coast.

3. Idling

Another sign of a bad valve is when your car begins to idle for an extended period at stoplights or stop signs. When this happens, there are high amounts of vacuum at the intake manifold since the throttle valve stays closed.

Also, the high vacuum attracts oil in the heads, and this causes them to concentrate on the valve stems.

On accelerating the car, the eroding seal allows oil to slip past, and it goes through the valve guide, which could burn the exhaust. A burnt exhaust will be evident with blue-white smoke exiting the tailpipe after acceleration from a stop. If this was to happen then speaking to a mechanic right away is essential. Good mechanics will have insurance for their business, so it is best to check first to see if they are covered in your local area, if not, then they may want to consider getting a quote as soon as possible to keep on with their trade as you search for one that does, even if it is further away as you do not want to have any more issues with your vehicle.

4. Excessive Oil Consumption

Oil in an engine helps to lubricate components so they can function smoothly. However, excessive oil consumption can be a problem since it would mean friction is not well handled.

Similarly, excessive oil consumption can cause bad valve seals. A loss of oil in the engine can be detected using the oil dipstick, therefore, you can determine if your oil is burning faster than normal.

If it is, the high consumption can either be a result of oil leakage or the oil burning excessively, which leads to a faster decrease in oil than normal.

To know whether this consumption is because of leakage or the valve, you need to check the engine if there is a leakage. If there are none, then you can attribute the excessive oil consumption to bad seals. Your vehicle, therefore, may be in need of a bad valve fix or a replacement entirely.

5. Excessive Smoke

The high presence of exhaust smoke, especially one that is blue-white and lasts longer after starting the car or accelerating is something of concern.

However, the smoke may disappear after a while, which could be misleading that all is well.

Nonetheless, bad valves may signal themselves in the issue of excessive oil burning while faulty piston rings and valve guides will cause excessive production of smoke.

6. Loss of Engine Power

Lack of acceleration power, when you engage the gas pedal, is also a result of faulty piston rings and valve seals.

Here, a compression test will help you to ascertain if the problem is due to the valve seal or the piston ring. You need to remove the EFI fuse and crank the engine, and then use the compression gauge to check the result.

In this case, an average or high level of compression shows that the problem is because of the valve seal, while the piston ring causes a low level of compression.



These are the bad valve symptoms, which are a clear indication that your car is in dire need of attention. Fixing the vehicle before the problem escalates can save you money in huge repairs since bad valve seals can also lead to other issues.

On the other hand, you need to seek the help of a professional and get your car off the road while its bad valves are being fixed.

And feel free to contact KB Delta for all your compressor valve needs and information about compressor valve parts.


bad valve symptoms - KB Delta

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