Below is the part three of Yuchai YC4108D-and-YC4108ZD series diesel engine generator operation and maintenance
manual. The main steps include fuel supply advance angle adjustment, valve
clearance adjustment, fuel injection pressure adjustment and oil pressure
adjustment.
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I Fuel Supply Advance Angle Adjustment
adjustments for the flange of fuel
injection of pump
a. adjustments for the flange of fuel
injection of pump
adjustment for the shaft of fuel injection of
pump
b. adjustment for the shaft of fuel
injection of pump
Technical data : Static fuel supply
advance angle is 14 ±2℃ A before TDC.
Fuel supply advance angle check: Unscrew
the nut which connect the high pressure fuel line for the No.1 cylinder and
fuel injection pump, crank the crankshaft slowly until the fuel level in the
delivery valve holder begins to fluctuate. At this time, the timing value
indicated by the pointer on the gear housing and the dial on the belt pulley
damper is the fuel supply advance angle.
Fuel supply advance angle adjustment:
There are three rectangle slots in the joint flange of the fuel injection pump,
through which three bolts are used to fasten the fuel injection pump to the
gear housing. After unscrewing these bolts, the fuel injection pump can be
rotated around its axis with small angle in order to adjust properly the fuel
supply advance angle. Crank the crankshaft to the position at which the fuel
will be delivered to the No. 1 cylinder
according to the above method, unscrew these bolts on the flange and all the joint
nuts for the high pressure fuel lines, rotate the pump a certain angle as
required (inner direction which means to increase the fuel supply advance
angle, outer direction which means to decrease the fuel supply advance angle) ,
then fasten the bolts on the flange. Check and adjust the fuel supply advance
angle to prescription, then fasten the bolts- on the flange.
If the bolts is adjusted to the dead
position on the rectangle slots in the flange and the fuel supply advance angle
still does not meet the prescription, remove the gear housing cover plate of
the fuel injection pump unscrew the three bolts used to fasten the gear of the
fuel injection pump rotate the pump (inner direction which means to decrease
the fuel supply advance angle, outer direction which means to increase the fuel
supply advance angle). At last fasten the bolts. Check and adjust the fuel
supply advance angle to prescription according to the above method, then
recheck whether the bolts are fastened and install the gear housing cover
plate. Pay attention to not damaging the gasket during adjustment in order to
avoid the fuel leakage.
II Adjustment Of The Valve Clearance
adjustment of the valve clearance
adjustment of the valve clearance
Technique demand ( cold state) : 0.4-0.05
mm
Intake valve clearance: 0.4±0.05mm
Exhaust valve clearance: 0.45±0.05mm
To determine the compression TDC of the
first cylinder: Rotate the crankshaft to make the TDC indicator, which is
mounted on the gear house cover, point to the "O" position on the
belt pulley damper. Then go on rotating in a small range of angles (100 ~200)
clockwise and counterclockwise. When the intake and exhaust rockers of the
first cylinder do not swing but those of the forth cylinder swing, rotate the
crankshaft hack to make the indicator point to the "O" position. At
this time, the piston of the first cylinder is on the compression TDC. If
counter, that indicates the forth piston is on the compression TDC. The first
piston can reach the compression TDC by rotating the crankshaft 360.
To adjust valve clearance: Rotate the
crankshaft to the position that the first piston is on the compression TDC,
when the No. 1,2,3 and 6 valves can be adjusted; and then rotate the crankshaft
3600, when the No. 4, 5, 7 and 8 valves can be adjusted. First, loose the
tightening nut of the adjustment bolt and screw the adjustment bolt out to the
suitable position, Then put the feeler gauge into the gap between rocker and
the end of valve stem. Next screw in the adjustment bolt till rocker can fasten
feeler gauge. Finally, tighten the tightening nut. A correct valve clearance
should he able to allow the feeler gauge move with slight resistance.
III Fuel Injection Pressure Adjustment
Technique demand
Fuel injection pressure 23±0.5MPa
26±0.5MPa (turbo charge)
fuel injection pressure adjustment
fuel injection pressure adjustment
Fuel injection pressure adjustment: Remove
the pressure - adjusting screw thimble, screw in or out the pressure -adjusting
screw as required. Screwing in means the increase of the injection pressure, on
the contrary, screwing out means the decrease of the injection pressure. The
fuel injection pressure can be adjusted on special test rig.
IV Oil Pressure Adjustment
Oil pressure adjustment
Oil pressure adjustment
Technical data : Oil pressure at idle
speed≥ 0.1MPa
Oil pressure at rated speed: 0. 25 ~ 0, 6MPa
Oil pressure adjustment: The,oil pressure
can be adjusted by the adjusting; screw of relief valve on the oil filter.
During adjustment, remove the nut on the relief valve, unscrew the locking nut,
screw in the adjusting screw with screwdriver, then the oil pressure will be
increased. If the adjusting screw is
screwed out, the oil pressure will decrease. After the adjustment fasten the
locking nut and nut. If the adjusted oil pressure does not meet the requirement,
check the trouble in the oil passages carefully and troubleshoot them.
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