How to adjust the WP12 in-cylinder brake valve?
3 Answers
The specific method for adjusting the WP12 in-cylinder brake valve is as follows: 1. Turn the engine until the first cylinder piston is at the firing top dead center position. 2. Adjust the intake valves of cylinders 1, 2, and 4. Loosen the intake valve lock nut and the intake valve adjustment bolt. Insert a 0.40mm feeler gauge between the valve bridge and the adjustment screw. 3. Rotate the adjustment screw to set the clearance to (0.40±0.06)mm. Then, tighten the lock nut using a torque wrench with a torque of (45±5) N.m. 4. Loosen the EVB bracket lock nut. 5. Rotate the EVB bracket adjustment screw to press the small piston until it is fully compressed (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 to set the exhaust valve clearance to (0.60±0.06)mm. Tighten the adjustment nut with a torque of (45±5) N.m. 7. Repeat the above steps to sequentially adjust the intake valve clearance for cylinders 3, 5, and 6, and the exhaust valve clearance for cylinders 2, 4, and 6.
When it comes to adjusting the WP12 engine's internal brake valves, I remember helping my cousin adjust the valves on his tractor-trailer. The key is to follow several steps: First, let the engine cool completely and remove the valve cover. Then, rotate the crankshaft to the top dead center position of the first cylinder and check if the marks align. Use a feeler gauge to measure the exhaust valve clearance—the factory specification is around 0.4 mm; neither too loose nor too tight is acceptable. If there's a deviation, loosen the lock nut, adjust the screw to the proper clearance, and then tighten it. Repeat this for each cylinder, and remember to double-check after adjustments. It's a meticulous job—over-tightening the screws can deform the valve stem, while too loose can cause a ticking noise. It's best to work with a partner.
Last time at the auto repair shop, I saw the mechanic adjusting the WP12 brake valve, and it left a deep impression. The engine must be completely cooled down. After removing the cover, locate the compression top dead center and secure the flywheel with a special tool. To measure the clearance, insert a feeler gauge between the rocker arm and the valve stem. For example, the standard clearance for the exhaust valve is 0.4mm, and any deviation exceeding 0.1mm requires adjustment. After loosening the lock nut with a wrench, use a screwdriver to fine-tune the screw until the feeler gauge can just be pulled out with slight resistance. The key is to adjust each valve in the order of the cylinders and then double-check by turning the engine twice to ensure everything is secure, as poor valve sealing can lead to oil burning.
