Tag Archives: valve seals

What are Symptoms of Bad Valve Seals?

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Valves regulate the amount of fuel and air mixture allowed in the cylinders for combustion. While the valves have guides or sleeves to keep combustion gases from passing through them, the seals on the top of the valves keep oil in the valve cover from being sucked down into the engine. Seals, typically made of high-strength rubber, fit over the top of the valve stem inside a small collar. When valve seals begin to wear or fail they produce some obvious and unique symptoms.

 

Cold Engine

One of the most noticeable signs of worn or cracked valve stem seals will be just after a cold engine start. If the vehicle has been sitting for any length of time or even overnight, the top of the head inside the valve cover will be coated with residual oil that was pumped up earlier during running operation. The rubber valve seal has also cooled during nonoperation, which causes it to contract and leave a small gap. When the engine first starts up, residual oil gets sucked down through the bad seal and into the combustion chamber. A large cloud of blue-white smoke will be seen exiting the tailpipe just after start-up.

 

Idle and Stop and Go Driving

Bad valve seals will show themselves during prolonged idling at stop signs or stop lights in congested city conditions. When the vehicle sits at idle for prolonged periods, high levels of vacuum at the intake manifold result because the throttle valve remains closed. The high vacuum attracts oil in the heads to congregate around the valve stems. Upon acceleration, the oil gets sucked past the eroding seal and down through the valve guide, where it burns in the exhaust. Huge clouds of blue-white smoke exit the tailpipe after each acceleration from a stop. The burning smoke will disappear during cruising or highway speed.

 

Off-Throttle Braking

Evidence of valve seals being compromised will show up during off-throttle braking, especially when descending a steep downgrade where the accelerator pedal remains static. With the creation of high intake manifold vacuum, coupled with the downward slant of the engine, oil collects toward the front of the valve cover over the head. Upon pushing the accelerator after a long coast, burned oil will exit the tailpipe in copious amounts. The engine will continue to burn the oil longer in this case, but it will still be a temporary condition until finally the smoking stops under normal cruise.

 

Oil Consumption

Bad valve seals will cause excessive oil consumption. In an otherwise normal engine with good compression, rings and valve guides, bad seals will cause a loss of oil that can be detected on the oil dipstick. By keeping an accurate record of oil level on the dipstick, a noticeable oil reduction due to the oil being burned along with the fuel will be discovered. Bad seals will be confirmed if no oil leaks can be found on the engine to account for the loss.

 

Excessive Smoke

If the valve seals have deteriorated enough, the blue-white exhaust smoke will last longer after start-up and acceleration. Yet the smoke will eventually disappear after long engine operation or during periods of hot weather. Bad valve seals nearly always show an intermittent problem of oil burning, whereas worn piston rings and valve guides will smoke during all times of engine operation and never disappear.

 

Get more information about valve seals, please do not miss the website of AOK Valve Stem Seals Ltd... The company can provide a variety of valve seals, o rings, and bonded seals for you. Try to check out their product pages and feel free to send inquiry to AOK for more details.

 

 

Article Source: It Still Runs

Bad Valve Seals and Piston Rings Symptoms & Replacement Cost

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This discussion is about the symptoms of bad valve seals and piston rings as well as their basic functions and common cost of replacement. Valve seals and piston rings are crucial for the functionality of your engine. If you can recognize the signs of when these components have problems, then you can replace them right away before serious damage is done to your engine.

 

Functions of Piston Rings

 

The piston is located inside of a car’s engine. The piston ring comes in the form of a split type ring and you install it outside of the piston’s diameter. The piston ring’s main purpose is to assist in sealing the combustion chamber, manage the oil consumption of the engine, and to assist in transferring heat to the engine from the piston. It is important to note that the piston ring will eventually get worn out, which means you’ll have to replace it. You should go to a professional mechanic to have this replacement job done.

 

Functions of Valve Seals

 

After air and fuel are mixed together, valves are there to manage how much of the mixture flows through the cylinders before the combustion process takes place. Valves usually have sleeves on them which prevent the combustion gasses from seeping out of them. The tops of the valves also have seals on them which prevent oil from getting pulled down into the engine area. These seals are commonly constructed out of a super strength rubber material and they’re placed into a small collar of the valve stem’s top area. Once these valve seals start to get worn out, you’ll notice some major symptoms that are unique to this problem.

 

The Symptoms of Bad Valve Seals and Piston Rings

 

The symptoms of bad valve seals and bad piston rings are quite similar. Any time either one of them fails, the performance of the vehicle will be reduced along with other bad symptoms that are noticeable. Let’s take a look at some warning signs which might indicate that you have bad valve seals or piston rings.

 

  • Exhaust Smoke – If you notice thick smoke that’s a gray or white color, this indicates that your car is burning oil. The only way this could happen is if the oil is leaking into the combustion chamber of your engine.

 

  • Too Much Oil Being Consumed – If the piston rings are worn out and the valve seal is broken, this will be what allows oil to flow into the combustion chamber.

 

  • Not Enough Accelerating Power – When there is damage to the piston rings and valve seals, the compression will be reduced which causes you to lose power in your engine. As a result, you won’t be able to accelerate when you put your foot on the gas pedal.

 

Although bad valve seals and piston rings have similar symptoms, the time and costs of repairing them are quite different. That is why you should educate yourself about where the problem is coming from, whether it’s the valve seals or piston rings. Once you find out, you can save time and money from having a mechanic figure it out for you.

 

To investigate where the problem is coming from, there are a few tips you can follow which will help you out with this. You can open the spark plug, fill up the cylinder with some oil, do a compression test, remove the EFI fuse and crank the engine, and then see the result of the compression gauge. If the result of the compression test appears to be good or at least average, then the piston rings are likely the problem. However, if the results of the compression test are low or under average, then the valve seals are the problem.

 

Replacement Cost of Piston Rings

 

When replacing piston rings, the cost will be determined by several factors. The make and model of your vehicle is one example. You also have to consider the type of engine that’s in your car and the condition of it. Most mechanics are going to charge around $1,500 minimum to perform this job. Some may even charge as much as $2,500. The reason this replacement job is so expensive is because it is a complicated task. The engine of the vehicle has to be completely disassembled first and then the cylinders of the vehicle have to be reconditioned. After that, the car gets reassembled using all the parts that were taken off originally. Only an experienced mechanic can perform this task, which is a very long and intense project that takes several hours to do.

 

Replacement Cost of Valve Seals

If you have discovered there is damage to your valve seals, then have an auto technician install new oil seals. The cost of this replacement job will be between $900 and $1,800, depending on the make and model of your vehicle. The process of replacing the valve seals requires disassembling the entire engine until you can reach the valve spring. Take off the cylinder head cover, the spark plugs, pushrods, and rocker arms. The amount of time this will take depends on the make and model of your vehicle. Sometimes the technician may have trouble with this job, so they’ll dismantle and remove the cylinder head. Then they’ll use a cylinder kit as a replacement which contains a cylinder head gasket.

 

Conclusion

 

There are lots of reasons why damage can occur to valve seals and piston rings. But if you regularly maintain your vehicle and get it serviced, then the damage to these components will be minimal. Vehicles that are maintained poorly or have high mileage are prime candidates for having damaged valve seals and piston rings.

 

If you are interested in learning more information about valve seals, try to visit the website of AOK Valve Stem Seals Ltd. AOK is a Taiwan local company of specializing in producing bonded seals, O-rings, and valve stem oil seals. Feel free to contact AOK you will obtain the details you need.

 

 

Article Source: http://cartreatments.com/valve-seals-and-piston-rings-symptoms-replacement-cost/