Inspecting The Fuel Injection Valve Injection Pressure And Spray Pattern - Komatsu 4D98 Series Shop Manual

3. Inspection and Adjustement
@ Apply oil to the contact between the
adjusting screw and push rod.
@ Turn the crankshaft 180° then and
make adjustment for the No.3 cylinder.
Then adjust the No.4 and No.2 cylin-
ders in this order.
The cylinder to be adjusted first does
not have to be the No.1 cylinder. Select
and adjust the cylinder where the pis-
ton is the nearest to the top dead center
after turning, and make adjustment for
other cylinders in the order of ignition
by turning the crankshaft 180" each
time.
3.6 Inspecting the Fuel Injection Valve Injection Pressure and Spray
Pattern
1
Wear protective g/asses when testing injection from the fuel injection valve. Never
approach the injection nozzle portion with a hand. The oil jetting out from the
nozzle is at a high pressure to cause loss of sight or injury if coming into careless
contact with it.
(1) Injection pressure measurement
1 Standard 1-1
Connect the fuel injection valve to the
high pressure pipe of the nozzle tester.
Operate the nozzle tester lever slowly
and read the pressure at the moment
when the fuel injection from the nozzle
starts.
If the measured injection pressure is
lower than the standard level, replace
the pressure adjusting shim with a
thicker one.
* Remove carbon deposit at the nozzle hole
thoroughly before measurement.
Injection nozzle
1
,/ \ Injection pressure measurement
with nozzle tester
Type of pressure adjusting shim thickness (mm) Injection pressure adjustment
0.13, 0.15, 0.18, 0.4, 0.5, 0.8
The injection pressure is increased by approx.
1.87 MPa(19 kgf/cm2) when the adjusting shim
thickness is increased by 0.1 mm.
3-4