How to adjust the exhaust brake valve of Weichai WP12?
2 Answers
Rotate to position the first cylinder piston at the top dead center of combustion. Adjust the intake valves of cylinders 1, 2, and 4. Loosen the intake valve lock nut, adjust the bolt, and insert a feeler gauge. Turn the adjustment screw and tighten the lock nut with a torque wrench. Loosen the EVB bracket lock nut and rotate the EVB bracket adjustment screw to compress the small piston until it is fully depressed. 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.
Last time I drove the company's Weichai WP12 truck on mountain roads, the exhaust brake failed and nearly caused an accident. I adjusted it myself. The method is quite simple: first, turn off the engine and let it cool for a while to avoid burns, then locate the adjustment rod of the exhaust valve. Use tools like a wrench or feeler gauge to measure the gap. The manual says 0.25 to 0.35 mm is optimal, but when I adjusted it, I just loosened the screw slightly, moved the wrench gently, and checked if the feeler gauge could pass. After adjustment, test it on a downhill slope—the braking was much more stable. Remember to wear gloves for protection and avoid touching the engine when it's hot to prevent valve damage. If the gap is too small or too large, the brake won't work properly. It's recommended to check it once a year to prevent wear and loosening from affecting safety. Long-haul drivers often encounter this issue, and improper handling can also increase fuel consumption. Newbies are advised to seek help from an experienced driver to avoid rework.