Valve stem oil seal shortcuts

摘要

The familiar black smoke on start-up and overrun can often mean an engine's valve stem oil seals have hardened and oil is leaking through to the combustion chamber. Fitting new valve stem oil seals isn't expensive, but the work involved is more time consuming than you'd expect. Traditionally, the cylinder-head needs to be removed, followed by the valves to allow the oil seals to be renewed. However, there is another method, which saves on a new head gasket and the removal of the cylinder-head. It involves accessing the tops of the valves, so the camshaft(s) must be removed in an overhead cam engine (SOHC and DOHC) or the rocker gear in an overhead valve engine (OHV). If space is available, the top of each valve spring can be compressed to remove the valve's collets and, in turn, provide access to change the valve stem oil seal.