How to adjust the valve of the upper and lower dead center of diesel engine piston

There are two common methods to check and adjust the valve clearance: one is the cylinder-by-cylinder adjustment method, that is, after the piston of a cylinder is determined to be at the compression top dead center position according to the cylinder ignition order, the clearance between the intake valve and the exhaust valve of the cylinder can be adjusted; After adjustment, turn the crankshaft and gradually adjust the valve clearance of other cylinders according to this method. Second, the method of twice adjustment is adopted, that is, the crankshaft is rotated to make the piston of the first cylinder at the compression top dead center, and the flywheel mark is aligned with the inspection hole mark line (such as EQ6 100 engine). At this time, the valves of 1, 2, 4, 5, 8 and 9 can be adjusted (referring to the sequence of engine valves from front to back); Then turn the crankshaft once, so that the six-cylinder piston is at the top dead center of the compression stroke, and then adjust 3, 6, 7, 10 "plus two valves (i.e. 1 1, 12), which is actually memory adjustment. When adjusting, while tightening the adjusting screw, insert the thickness gauge between the valve stem end and the rocker arm and pull it back and forth. If you feel slight resistance, check it again until it is suitable. The cylinder-by-cylinder method requires the crank to rotate the crankshaft more times, and the inspection and adjustment time is longer. However, for the seriously worn engine, the cylinder-by-cylinder method is more accurate to check and adjust the valve clearance. Adjusting the valve clearance twice saves time and effort, but it is difficult for maintenance personnel to remember the different adjustable valve serial numbers of different models, which is more complicated.

Open the valve cover, turn the engine, and adjust the cylinder at the top dead center, so as to see which cylinder is compressing the top dead center: 6-cylinder machine: adjust cylinder 1 see the exhaust valve of cylinder 6 up and down, and then adjust cylinder 1 when the intake valve starts down again, adjust cylinder 6 1, adjust cylinder 3 to see cylinder 4, adjust cylinder 4 to see cylinder 3, and adjust cylinder 2 to see cylinder 5.

Specific adjustment method: loosen the lock nut of the adjusting screw on the rocker arm, select the feeler gauge according to the standard clearance, put it between the rocker arm and the valve, turn the adjusting bolt with a screwdriver and pull the feeler gauge. When the tip feels friction, do not move the screwdriver and tighten the lock nut.