What is the valve adjustment method of four-cylinder diesel engine?

When adjusting the Pacific Auto Network, firstly loosen the lock nut and the adjusting screw, insert the thickness gauge with the same thickness as the specified value of the valve clearance into the gap between the adjusted valve foot and the rocker arm, adjust the valve clearance by rotating the adjusting screw, and pull the thickness gauge back and forth until the thickness gauge has slight resistance. Check again after tightening the lock nut, and readjust if the clearance changes.

The adjustment position of valve clearance depends on the structure of valve mechanism.

The valve clearance of the rocker valve train is adjusted by the adjusting screw at one end of the rocker push rod, as shown in the following figure (a). When adjusting, loosen the lock nut and adjusting screw first, insert the thickness gauge with the same thickness as the specified value of the valve clearance into the gap between the adjusted valve foot and the rocker arm, adjust the valve clearance by rotating the adjusting screw, and pull the thickness gauge back and forth until the thickness gauge has slight resistance. Check again after tightening the lock nut, and readjust if the clearance changes.

For www.QcWxjS.com overhead camshaft engine without rocker arm, the valve clearance is usually adjusted by replacing gaskets with different thicknesses on the tappet, as shown in the following figure (b).

Because the valves of each cylinder of the engine can't be closed at the same time and the valve clearance can't be adjusted at once, cylinder by cylinder adjustment method or secondary adjustment method can usually be adopted.

The adjustment steps of the cylinder-by-cylinder adjustment method are as follows: 1 Turn the crankshaft of the engine to make a cylinder at the top dead center position of the compression stroke, at which time the intake valve and exhaust valve of the cylinder are closed.

There are many methods to determine whether the cylinder is at the top dead center position of the compression stroke. For example, according to the mark of the top dead center position of the first cylinder on the crankshaft pulley, the crankshaft is rotated so that the piston of the first cylinder is at the top dead center position of the compression stroke, and then another cylinder can be positioned at the top dead center position of the compression stroke every 720/i (number of cylinders). By observing whether the valves of the corresponding cylinders are in an overlapping state or not, the crankshaft is rotated, and at the same time, the valves of the corresponding cylinders (i.e., cylinders in which the pistons simultaneously rise and fall) of the cylinders whose valve clearances are to be adjusted are observed. When the exhaust valve is completely closed and the intake valve starts to open, the cylinders are in an overlapping state, and the cylinder whose valve clearance is to be adjusted is at the top dead center position of the compression stroke.

2 Check and adjust the gap between the intake valve and the exhaust valve of the cylinder.

If it is a valve mechanism with a rocker arm, you can loosen the lock nut of the valve adjusting screw on the rocker arm with a wrench and screwdriver, insert the thickness gauge between the valve stem and the rocker arm, and twist the adjusting screw so that the thickness gauge can be slightly pressed down and pulled out with a little pressure. Tighten the lock nut after adjustment, and then recheck it with a thickness gauge.

3 Turn the crankshaft and check and adjust the valve clearance of other cylinders in the same way. It can be seen that for a multi-cylinder engine, the method of cylinder-by-cylinder adjustment requires multiple cranks to turn the crankshaft, and the total time is more. However, this method adjusts the valve clearance more accurately.

The twice adjustment method is to adjust all valves on the engine twice. The method is simple in operation and high in working efficiency.

(Photo/Text/Photo: Pacific Auto Network Q&A called Beast)