How to adjust the valves of Weichai P12 engine?
2 Answers
Weichai P12 valve adjustment method steps are as follows: 1. Rotate to position the first cylinder piston at the explosion top dead center; 2. Adjust the intake valves of cylinders 1, 2, and 4, loosen the intake valve lock nut, loosen the intake valve adjustment bolt, and insert a 0.40mm feeler gauge between the valve bridge and the adjustment screw; 3. Rotate the adjustment screw to adjust the clearance to (0.40±0.06)mm, then tighten the lock nut with a torque wrench to a torque of (45±5)Nm; 4. Loosen the EVB bracket lock nut; 5. Rotate the EVB bracket adjustment screw to compress the small piston until it is fully depressed (be careful not to open the valve); 6. Insert a 0.60mm feeler gauge between the exhaust valve adjustment screw and the middle plane of the valve bridge, adjust the exhaust valve clearance and lock screw, adjust the exhaust valve clearance to (0.60±0.06)mm. Tighten the adjustment nut to a torque of (45±5)Nm; 7. Finally, repeat the above steps to adjust the intake valve clearance of cylinders 3, 5, and 6, and the exhaust valve clearance of cylinders 2, 4, and 6 in sequence.
When adjusting the valve clearance of the Weichai P12 engine, it's best to do it when the engine is completely cooled. I've worked on diesel vehicles for many years, and this is not something to be careless about. First, locate the top dead center position of each cylinder's compression stroke, usually by turning the crankshaft with a wrench until you hear a 'popping' sound. Then use a feeler gauge to measure the valve clearance. The standard value is generally between 0.25 to 0.35 mm, but always refer to the manual for your specific engine model. If adjustment is needed, loosen the lock nut and carefully turn the adjusting screw until the feeler gauge can just slide in with slight resistance, then tighten the lock nut. Check each valve repeatedly to avoid excessive clearance causing noise or insufficient clearance leading to valve burning. If you lack experience, it's better to leave this to professional mechanics. Improper adjustment might damage the valve train - last time I made just a tiny mistake and it caused starting difficulties, nearly requiring an engine replacement. Regular valve clearance adjustment can save fuel, extend engine life, and make the engine run smoother.
