WEICHAI & PSI SERVICE MANUALS AVAILABLE ONLINE AT FLYPARTSGUY.COM Weichai America Corp. Clean the cylinder head, focusing on the combustion chamber surface, valve seat, intake and exhaust valves, and intake and exhaust passages. Remove the carbon deposits and mucilage glue, and check the surface condition. 1. Appearance Inspection: Check the cylinder cover for any discoloration or cracks. If any cracks are discovered, a leak test should be done. 2. Valve Recession: Valve recession is the vertical distance between valve undersurface and cylinder cover undersurface.
Any difference between the measured and required values of valve recession can reflect the degree of wear on the valve and valve seat. A depth micrometer can be used to measure valve recession, as shown in Figure 9-7 below: Fig. 9-7 A Depth Micrometer Reference Table 9-1 for valve recession requirements. If valve recession exceeds the allowed range, the cylinder cover must be replaced to ensure engine reliability. If valve recession doesn’t exceed allowed range, disassemble the valve and check the sealing surface between the valve and valve seat for wear and abnormal damage.
Table 9-1 Valve Recession Specifications Required value of valve recession (mm) Intake valve 1.00~1.45 Exhaust valve 1.00~1.45 Revision: August 2019 43 GET YOUR WEICHAI & AFTERMARKET SERVICE PARTS AT FLYPARTSGUY.COM