passage in filter housing to the outside of filter element.
A spring loaded bypass valve on front of filter housing
maintains a maximum pressure of approximately 15 psi
(2) On engine Model DSSSTA.
on the fuel in filter housing; as indicated on fuel
(a) Refer to figure 344 and remove
pressure gauge mounted on housing. This fuel transfer
glow plug to prevent damage.
pump supplies more fuel than is required by engine, or
(b) Remove remaining items in
to maintain 15 psi pressure. Excess fuel is bypassed
around valve and returned to fuel tank. Filtered fuel
flows up center of filter housing into a passage through
(c) Install by reversing procedure
cover then down rear of housing to fuel manifold, which
distributes fuel to the injection pumps. A cam activated
injection pump for each cylinder, forces fuel through an
3-65. Air Cleaners
injection line to proper fuel injector where a definite
quantity of fuel is forced into pre-combustion chamber at
Used by Engine Model 687C-18-ES.
the proper time.
(1) Removal and installation.
Fuel System Flushing Procedure for Engine
sequence, and remove air cleaner from engine.
(1) Operate vent valve at front of filter
Install in reverse order.
(2) Disassembly and Reassembly. Refer to
sequence and disassemble air cleaner.
several times, until a solid stream of fuel flows out of the
drain tube, indicating that all air has been flushed from
Reassemble in reverse order.
(3) Close the vent valve.
through 33 in numerical sequence and remove mounting
bracket from engine. Install in reverse order.
The fuel system may also be flushed
(4) Cleaning, inspection and repair.
by using transfer pump to force fuel
(a) Clean all parts with an approved
out of drain tube. Open vent valve
cleaning solvent and dry thoroughly.
and operate starter for approximately
(b) Visually inspect for dents, breaks,
thirty seconds, or until a solid stream
cracks, stripped threads on mounting hardware, or
of fuel flows out of drain tube,
whichever requires the shorter time,
(c) Repair by replacing defective
then close vent valve.
packing, hardware, or damaged air cleaner.
Fuel Injector and Fuel Line
Service air cleaner as
General. Fuel injector or fuel line that is
loose, damaged, or defective will effect diesel engine
operation. When it is suspected that a fuel injector is
defective, the defective injector can be isolated by the
following process of elimination:
(1) Loosen fuel line coupling nut at fuel
injector while engine is idling, and observe engine
(2) If idling speed slows down, the injector
(3) If there is no noticeable difference in
engine speed, that injector is defective. Repeat on
remaining five injectors. Replace a defective injector or
damaged fuel line.
Removal and Installation.
(1) On engine model 687C-18-ES.
Figure 3-44. Fuel injector, fuel line and glow plug,
items in numerical sequence.
removal and installation.