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Valve Stem Sealing


It is quite disgusting if you drive behind such a stinking vehicle. As there are almost no two-stroke engines any more, and diesel engines have become almost smoke-free, vehicles with oil in the exhaust gas are all the more striking. Maybe the cylinder guide is worn out, more probable is a defect in the valve stem sealing which is not quite so easy to repair in case of an overhead camshaft engine. What has to be done:
- dismounting the camshaft,
- rocking lever, cam follower or bucket tappet,
- pressure build up in the cylinder,
- valve spring.

How it works

As the picture on top points out, a valve stem sealing consists, e.g., of a metal plate on which the valve spring is positioned. The plate continues upwards as a pipe piece. In the inside elastic-like material is vulcanised which forms a sealing ring above the small pipe piece. This seals the oil space towards the valve stem in the upper part of the cylinder head against the inlet port or exhaust channel. An outside spring around the sealing ring exerts additional pressure on the ring.

In addition, the metal plate at the lower end prevents a breaking in of the valve spring into the cylinder head in case of a missing socket for the valve spring. Side forces would develop that could possibly cause valve demolition. Also the twisting movements of the valve are suppressed less, too much wear is prevented. Mounting the valve stem sealing you should pay attention to the fact that the fine sealing. lip does not become broken at the upper valve prick. As an auxiliary means there are thin metal tubes that are pushed over the valve stem. 06/08

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