Valve guide is generally made of independent, and then pressed into the cylinder block or cylinder head with a small amount of public surplus, because the valve and valve guide between the lubrication is more difficult, so its clearance can not be too small, otherwise it will increase the wear of both.
The role of valve guide
Valve guide is a hole in the cylinder head to support the valve, it is equivalent to a bushing, the valve rod can slide in it. The valve guides are part of the cylinder head and help support and position the valves so that they can seat properly. The valve guide also serves as a heat sink. The heat generated in the combustion chamber passes through the valve and then to the valve guide, then to the cylinder head and finally to the cooling system.
The clearance between the valve stem and the valve guide is very important. Generally this clearance is between 0.2-0.4mm. If the valve guide is worn and the clearance becomes large, it may lead to a variety of failures in the diesel generator set. For example, the valve may leak, leading to changes in the air-fuel ratio; oil may leak through the valve guide, leading to increased oil consumption; the valve may also fail to seat smoothly, leading to rapid wear of the valve seat. Excessive valve clearance can increase oil consumption and there will be burned oil in the exhaust gas.
Types of valve guides
Generally, there are two types of valve directors for diesel generator sets, namely one-piece director and inserted type, one-piece director is machined directly in the cylinder, and inserted type is some small round tubes pressed into the cylinder head. However, the one-piece tube cannot be replaced in this way.
