Yanmar 4TNV98, Service Manual

Page: 169 / 246

4TNV98 & 4TNE98 Diesel Engine Section 4. Fuel System 167
See the parts catalog for available shims.
CAUTION
Each pressure adjusting shim removed or
added changes the pressure threshold by
approximately 275 psi (1.9 MPa, 19 kgf / cm²).
Adding adjusting shims increases the threshold
pressure. Removing adjusting shims reduces
the pressure threshold.
1. Disassemble the fuel injector assembly. See
Disassembly and Inspection of Fuel Injectors on
page 165.
2. Remove or add adjusting shims as needed.
3. Reassemble the fuel injector assembly. See
Reassembly of Fuel Injectors on page 166.
4. Retest the fuel injector. See Testing of Fuel
Injectors on page 164. If the injector cannot be
adjusted to the appropriate pressure, discard the
fuel injector.
Reassembly of Fuel Injectors
1. Secure the injector in a soft-jawed vise with the
nozzle end up.
2. Reinstall the shims, nozzle spring, nozzle spring
seat, valve stop spacer, nozzle valve, and nozzle
body.
3. Reinstall the nozzle case nut. Tighten it to
specification. See Special Torque Chart on page
143.
Installation of the Fuel Injectors
4-Valve Cylinder Head
1. Reinsert a new nozzle seat (Figure 7-57, (6))
and nozzle protector (Figure 7-57, (5)) in the
cylinder head for each injector.
2. Reinstall a O-ring on to each injector body.
3. Reinsert each fuel injector (Figure 7-57, (4)) into
the cylinder head.
4. Reinstall the fuel injector retainers (Figure 7-57,
(3)) and torque the retaining bolts (Figure 7-57,
(2)) to specification.
5. Reinstall the fuel injector return line assembly
using new gaskets on each side of the injector
line screws.
6. Reinstall the fuel high-pressure fuel lines to each
injector and tighten the nuts using a “line” or
“flare nut” wrench.
Figure 7-57
7. Prime the fuel system. See Priming the Fuel
System on page 15.
8. Operate the engine and check for fuel and
coolant leaks.