What is the method for adjusting valve clearance?
2 Answers
Adjustment methods for valve clearance: 1. Cylinder-by-cylinder adjustment method: Rotate the crankshaft to the compression stroke of cylinder 1 and adjust the intake and exhaust valves of cylinder 1. Then turn the crankshaft to bring the next cylinder to the compression stroke in the firing order, and adjust the intake and exhaust valves of this cylinder. Repeat this process until all cylinders are adjusted one by one. 2. Two-step adjustment method: In production practice, the two-step adjustment method is commonly used to adjust valve clearance. When cylinder 1 is at top dead center of the compression stroke, adjust half of all valves. Then rotate the crankshaft one full turn to adjust the remaining half of the valves. The adjustment is completed in two steps. The specific steps for adjusting valve clearance are: First, loosen the lock nut and insert a feeler gauge with the specified clearance thickness between the valve stem end and the rocker arm. Simultaneously rotate the adjustment screw (clockwise rotation decreases valve clearance; counterclockwise rotation increases valve clearance) until slight resistance is felt when pulling the feeler gauge. Finally, secure the adjustment screw with the lock nut. Ensure the valve clearance does not change during locking. After adjustment, recheck with the feeler gauge once more. If there are any changes, readjust accordingly.
I've adjusted valve clearances many times, and the key is the engine must be completely cooled, otherwise thermal expansion will affect measurement accuracy. First, park the car on level ground, wait three to four hours after turning off the engine to let it cool thoroughly. Then, I locate the top dead center mark on the crankshaft - usually removing spark plugs makes it easier to rotate the crankshaft. After aligning the compression top dead center position, open the valve cover and use a feeler gauge to measure the clearance between the rocker arm and valve stem. If the gap is too small, loosen the adjustment screw with a wrench; if too large, tighten the screw. Check each valve individually, adjusting to the specifications in the vehicle manual - neither too tight nor too loose. After finishing, reinstall the cover and start the engine to listen for smooth, noise-free operation. This job requires precision - I typically complete it in about thirty minutes per vehicle. Regular adjustment prevents increased fuel consumption and valve damage.
