This is the part two for Shangchai W series diesel engine taks and engine maintenance. At the part one, we mainly tale about Shangchai W series diesel engine maintenance plan, including checking engine periphery, checking fuel tank and checking air filter. In this part, we are going to learn how to check valve clearance, check intake system, add grease, check fuel pump coupling, check fuel injector and so on.
When doing the first maintenance for a new or overhauled engine, conduct valve-clearance checking to timely regulate and correct the initial changes of the valve clearances. Later valve clearance checking and regulating should be done based on the maintenance plan if the engine operates normally.
Valve clearance checking should be conducted after the engine has bean stopped and the coolant temperature fails to below 60℃.
(1) Remove the nut on the valve cover
(2) Remove the observing window plate on the flywheel housing.
(3) Rotate the engine in the direction indicated by sign near the observation window on the flywheel housing to make the piston of No.1 or No. 6 cylinder position at the top dead center on consumption stroke. When the indicator on the flywheel housing points at mark “0” in the flywheel viewed from the observing window on the flywheel housing, the piston of No 1 or No. 6 cylinder is at the top dead center.
Note:
(1) Rotate the engine for generator sets: loosen the bolts, remove barring shaft fixing plate (1) and push the barring shaft (2) inwards till it engage with the ring gear. Use tool to turn the barring shaft to rotate the engine.
(2) Rotate the engine for marine application: rotate the engine with the help of bolt of the front pulley.
(3) Check if the rocker arms of No. 1 cylinder are loose. If they loose, the piston of No. 1 cylinder is at the top dead center on compression stroke; if not, the piston of No. 6 cylinder is at the top dead center on compression stroke.
(4) When the piston of No 1 cylinder is at the TDC on compression stroke, check with a feeler gauge the intake valve clearance of No. 1, 2 and 4 cylinder, as well as the exhaust valve clearance of No 1, 3 and 5 cylinders. When the piston of No 6 cylinder is at the TDC on compression stoke, check with a feeler gauge intake valve clearance of of No. 3, 5 and 6 cylinder as well as the exhaust valve clearance of No. 2, 4 and 6 cylinders.
Note: The clearance is correct when some resistance is felt at which the feeler gauge is slipped between a valve bridge and a rocker arm.
(5) If a valve clearance fails to meet the requirement, loosen the adjusting screw locknut on the corresponding rocker arm, adjust the clearance to the specified value and tighten the locknut to 125±6 N*m. check the valve clearance again and it should not change.
Valve clearance:
Intake...........................0.04 mm
Exhaust........................0.45 mm
(6) Mark a sign on the damper and rotate the crankshaft for a circle (360°). follow the same steps to adjust the rest intake and exhaust valve clearances.
(7) Install the valve cover. Check the valve cover seal and gasket and replace them if necessary. Tighten the cover bolts to 75-85 N*m.
Check the intake house for any crack, as well as perforation, and clamps for looseness. Replace the hose(s) if any fault is found, and tighten clamp screw(s) if looseness is found to ensure the intake system free from leakage.
Add proper amount of sodium based lubricating grease into the small hole of the water pump for bearing lubrication.
Check the coupling bolts for looseness and tighten them when required. Visually check the sheet steels of the coupling for crack or other faults and replace the coupling if necessary.
Warning: Be careful when replacing oil because skin contact with the hot oil or hot engine surface would cause scald.
(1) Do not stop the engine until the temperature of coolant reaches 60℃,then remove the two oil drain plugs (one on the bottom of the fuel pump and the other on the governor housing), scrap the washers and drain the oil.
Caution: it takes longer time to drain oil because oil enters the governor from the fuel pump through the bearing clearance.
Caution: Do not drain engine oil when engine is in cold-state at which foreign particles has deposited and attached to the bottom of the governor, and will not drain with oil. When engine oil is warm, foreign particles suspend in it and can easily drain with engine oil.
(2) Clean the installation surface of the oil drain plug on the governor. Install the oil drain plug with a new washer and tighten it to the specified torque: 40-50 N*m (one on the fuel pump), 12-15 N*m(one on the governor housing).
(3) Unscrew the oil dipstick and add clean oil to the upper mark in the dipstick.
Caution: It takes longer time add oil to the fuel pump for oil gets in the fuel pump from the governor through the bearing clearance.
(4) Tighten the dipstick slight.
(5) Start the engine and run it at idle. Check the oil di[stick for oil leakage.
(6) Stop the engine and wait for 15 minutes to allow the oil flow back to the governor, and then check the oil level. Add oil to the upper mark in the dipstick when required.
(7) Tighten the oil dipstick to a proper degree.
Check the atomization of the fuel injectors at test bench. Proper atomization shall be in long thin cone of even fuel distribution. An injector is in problem if any of the following is found. Checking and repairing must be made and replacement must be performed if necessary.
The opening pressure of the injector is designed to be 25-26 MPa. When the opening pressure is significantly reduced, the atomization is deteriorated;
Fuel spray is in split state;
No atomization takes place, rather in thick line;
Fuel drips.
Perform visual check on the air inlet and outlet chambers of the intercooler for crack, perforation or other damages, and on the air inlet and outlet pipes of the intercooler for sealing-off and other damages. Replace the intercooler if necessary.
Check the zinc bar for erosion and replace the zinc bar if it is in bad erosion.
Perform visual check on the hoses of the air inlet and outlet pipes and water inlet and outlet pipes (water-to-air intercooler) for crack, and check clamps for looseness. Replace the hose(s) if nay fault is found, and tighten clamp screws if looseness is found.
Calibrate all the instruments
Remove the drive belt. Turn the fan to check the fan bearing for normality. When rotating the fan, there should be no vibration or excessive axial movement. Replace the fan hub if necessary.
Perform visual check on the impeller blades of the turbine and compressor of the turbocharger for damage, crack, or contact with their housings when a light finger pressure applied on them. And check the turbocharger shaft for not being free spinning. In case that any of the above problems occur, the turbocharger should be replaced.
Check the vibration damper for damping fluid (silicon fluid) leak and surface dents. Also examine the thickness of damper to confirm if the damper become deformed. In case that any of the above problems occur, the damper should be replaced.
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