Exhaust Valve Yanmar 104211-11110

Function and technical context

The exhaust valve is part of the cylinder head distribution train and is responsible for opening and closing the exhaust duct of combustion gases to the exhaust manifold. In Yanmar HM and GM series marine diesel engines, this component works under high temperature and cyclic pressure conditions, as it seals the combustion chamber in each engine cycle. Poor sealing causes loss of compression, notable reduction in power and, in advanced cases, damage to the cylinder head or piston. As it is a three-cylinder engine, three units are required per engine to complete the timing assembly repair.

When to replace this part?

The most common symptoms of exhaust valve wear are: progressive loss of compression in one or more cylinders, persistent bluish or black smoke from the exhaust, difficult starting and drop in engine performance under load. In marine engines subjected to intensive use or many hours of navigation, it is recommended to check the condition of the valves—including clearance and seat—at each major cylinder head overhaul. Replacing the exhaust valve preventively during a cylinder head overhaul prevents a second opening of the engine in open water, which can involve grounding and assistance costs much higher than the value of the part.