Symptoms of Bad Valve Seals (2024)

Valve Seals Help Control Oil Consumption and Valve Lubrication

Valves are an important part of regulation in any system, and their sealsare designed to be used in different types of engines for controlling oil consumption, and valve lubrication.The design and manufacturing of the seal is the key to ensure seal performance and longevity.

Valves have many uses and are found in virtually every industrial process, including water & sewage processing, mining, power generation, processing of oil, gas & petroleum, food manufacturing, chemical & plastic manufacturing and many other fields.

Some examples of valve seals include: ball valve seats, globe valve discs, stem packing, stem seals, valve discs, valve packing, valve seals, and valve stem packing.

Having a proper valve seal can save you thousands of dollars in repairs at the end of the day, so it's important to check them semi-regularly. For example purposes, we'll focus on cars, but this can be translated across a variety of systems and industries. Here are some symptoms of a bad valve seal that may need to be replaced:

Performing the Cold Engine Test

One sure-fire way to tell if you have a faulty valve seal is to perform a cold engine test. When your vehicle has been sitting overnight or for a longer period of time, the top of the head of the valve cover will have some oil left over from the last time you drove. When you start the engine, the oil ends up getting sucked down through the bad seal into the combustion area, producing a blueish smoke out of the tailpipe. This may indicate that your valve is not securely sealed and that it’s time to get a new one.

Idling

Another way to test a bad valve seal is to be aware of what happens while your vehicle is idling. When your vehicle is stopped for a significant amount of time, high vacuum levels will cause the oil to build up around the valve system while it is closed. In a faulty valve seal situation, when you begin to accelerate again, this oil can end up getting sucked past the seal an into the valve guide. This causes more of this blueish smoke, due to the burning of oil, to come out the tailpipe.

High Levels of Oil Consumption

High levels of oil consumption is another indicator that you have a bad valve seal. This is because oil is being leaked out or burned excessively and causing oil to decrease at a higher rate than normal. You can detect this loss of oil with a basic oil dipstick and keeping a regular log of oil levels. If no oil leaks can be found around the vehicle, you may still have a bad valve seal, as the oil will likely be burned up causing excessive smoke.

High Levels of Smoke

Another indicator of a faulty valve seal, as mentioned above, is the high presence of smoke. It’s common for some exhaust smoke to be present when you first start your vehicle, but if it begins to last longer than normal, your valve seal may be deteriorating. In addition, if you have a bad valve seal, the excessive smoke will tend to come in waves as an indicator of oil burning.

Engine Braking Test

Engine braking is when other ways besides external braking are used to slow down your vehicle within an engine. When you have a bad valve seal, the oil that collects at the front cover of the head will end up burning when you push on the accelerator after coasting for a while. This is apparent especially when going downhill and again will be indicated by the excessive smoke that leaves the tailpipe. The oil here burns longer than in normal cases.

Acceleration Power is Compromised

The final indicator of a poor valve seal is a lack of acceleration power. You can also perform a compression test to see if this is the case. A higher level of compression will indicate that it’s a valve seal problem, while a low level of compression will indicate a piston ring problem. These two areas can be very similar in their faulty symptoms so it’s best to be informed on their differences.

A badly designed seal can result in engine oil flooding, which can eventually cause a breakdown. Gallagher Fluid Seals understands the importance of a well-designed industrial seal and can help design a custom solution for you, or supply you with standard off-the-shelf seals from the world's top suppliers.

For more information about valve seals what why they fail, or to find solutions, contact Gallagher's engineering department.

The original article can be found on Real Seals' website.

Symptoms of Bad Valve Seals (2024)

FAQs

Symptoms of Bad Valve Seals? ›

The final indicator of a poor valve seal is a lack of acceleration power. You can also perform a compression test to see if this is the case. A higher level of compression will indicate that it's a valve seal problem, while a low level of compression will indicate a piston ring problem.

What are the symptoms of bad valve seals? ›

Warning signs of a bad valve seal
  • Where there's (blue) smoke, there's fire. Starting a cold engine is often a good way of determining the health of the valve seals. ...
  • Idling. A similar phenomenon happens when idling. ...
  • Excessive smoking. ...
  • Higher levels of oil consumption. ...
  • Engine braking test.
Jan 31, 2022

How do I know if I have bad valve seals or piston rings? ›

The final indicator of a poor valve seal is a lack of acceleration power. You can also perform a compression test to see if this is the case. A higher level of compression will indicate that it's a valve seal problem, while a low level of compression will indicate a piston ring problem.

How to know if valves are bad? ›

Here are a few of the symptoms:
  • Popping/Ticking Noise. The first sign of faulty valve seals in your car is popping noises. ...
  • Blue Exhaust Smoke. ...
  • Excessive Oil Consumption. ...
  • Rough Idling. ...
  • Cold Engine. ...
  • External oil leaks. ...
  • Loss of Power. ...
  • Increased Fuel Economy.
Nov 10, 2022

Do bad valve seals affect compression? ›

Exhaust valves and air intake valves at the top of the cylinder can also get overheated, and leak gas or the valve seals can become too worn to seal the gas in properly. Either way, the result is often low compression. Several valve problems can lead to low compression.

How to check if valves are leaking? ›

Listening for Leaks: Sometimes, leaks can be detected by listening for unusual hissing or escaping air or fluid near the valve. Use a stethoscope or simply lean closer to the valve while it's operational (if safe to do so) to listen for any unusual sounds.

What is the life expectancy of valve seals? ›

Valve stem seals often last more than 150,000 miles under normal driving conditions. Infrequent oil and filter changes may cause valve stem seals to fail prematurely. Improper installation often causes valve stem seals to fail shortly after installation.

What are the symptoms of worn piston rings and cylinders? ›

Bad piston rings will cause the color to change or deepen dramatically. When the piston ring fails or becomes too worn to form a seal, the exhaust turns to a thick, dark gray, or bluish color. You might also smell burning oil.

Can bad valve stem seals cause blowby? ›

No. Blowby refers to combustion gases getting past the piston rings and into the crankcase. Worn valve stem seals will cause excessive oil consumption, because the oil will be sucked past the seals and down through the intake valve guides by vacuum.

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

If you see any water leaking from your valves, it's a sign that they need to be replaced. If a valve begins to leak, it can lead to significant water waste. For example, the average household with one leak wastes more than 10,000 gallons of water annually.

What is the most common valve failure? ›

Any valve can be affected by disease, but damage leading to failure is most common in the mitral valve.

Will a bad valve show up on a compression test? ›

A bad exhaust valve that leaks will be eroded away to the point the cylinder is drastically down on power and doing a compression test it will show '0' psi.

Can bad valve stem seals cause low compression? ›

A bad stem seal will enable oil burning. It will not cause bad engine compression, but if the Valve guide to valve stem is badly worn and loose the valves may not seat meaning the compression will be poor and the stem seals will be worn out also- that repair means removing the head for a rebuild.

Can you change valve stem seals without removing the head? ›

Yes, I've done a few that way…. put the piston at BDC, pull the spark plug, and stuff as much small rope into the cylinder as you can, then rotate the engine backwards to push the piston up, smashing the rope and that will keep the valve from falling out. Then you can remove the valve spring and replace the seals.

How do you tell if you need a new valve stem? ›

Check the valve stem for leaks.

After the tire is inflated and back on the wheel, check it for leaks. You can spray it with a water and soap solution to ensure nothing bubbles. If you see bubbles, you need to install a new valve stem.

Are valve seals expensive to replace? ›

Twelve valve seals might cost $25. One valve cover gasket might cost $15. Using the old “rope trick” procedure, you might spend an hour on this job.

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