Valve Stem Seal are designed to make sure no oil will spill into the engine piston as it eat the gas coming from the Fuel injector through the exhaust manifold.
It is a small round rubber are plastic seal with a hole in the center of it, And it goes over the valve stem in the head to keep oil from running down and into the combustion chamber- where the spark plug goes into the head. If you remove the valve cover you will see several springs and they go over the valve stem and seal.
The o ring style seal goes on the lower groove, the valve keeper goes in the top groove.
Rubber valve stem seals are the parts used to keep tires from leaking around the valve stems. They provide a tight seal which also keeps them securely in place.
If the refrigerant has escaped, get a a/c valve stem kit from a autoparts store. They cost a few dollars and come with a stem tool and a few valve stem core that resemble tire valve stem cores. If you still have pressure, you will need a special tool that costs about 40 bucks.
The engine valve stem seals are worn. Usually valve stem seal replacement is all that is needed, occasionally there is wear in the valve stems and/or valve guides which requires further repair.
What do you want to know? Take the heads off, remove the valves, and springs to get to the valve stem seals
Yes. Depending on what type it is. The stem can strip so it will not close, the washer can break up so it does not seal. A gate valve can corrode and not seal completely. Lots of ways for one to fail.
If the valve stem seals are bad the intake valves will "suck" oil into the cylinders. One common indicator of worn valve stem seals is to take your foot off the accelerator for several seconds when going downhill, then watch for smoke when you step on the accelerator again. If you see a puff of BLUISH smoke, you probably have bad valve stem seals. The catalytic converter can become oil fouled so that would be another indicator that you might have valve stem seal problems.
If the valve stem seals are bad the intake valves will "suck" oil into the cylinders. One common indicator of worn valve stem seals is to take your foot off the accelerator for several seconds when going downhill, then watch for smoke when you step on the accelerator again. If you see a puff of BLUISH smoke, you probably have bad valve stem seals. The catalytic converter can become oil fouled so that would be another indicator that you might have valve stem seal problems.
seems a mid sized ship. your question is however not clear.
The pipe - the valve stem - is narrower at the top. And the valve spindle sits with a thicker part below the narrower part of the stem. When you turn the little nut on top of the spindle you pull the thicker part of the spindle into the narrower part of the stem to create a seal and to close the valve. To open you unscrew the nut and push the spindle down.
You may be referring to the valve stem on each wheel.