Section VII. NOZZLE HOLDER ASSEMBLIES
a. Each engine cylinder is provided with a multi-
hole, differential needle, hydraulically lifted, nozzle
The function of each nozzle holder
assembly is to direct a metered quantity of fuel re-
ceived from the fuel injection pump into the corres-
ponding engine combustion chamber in a highly atom-
ized, pre-determined spray pattern in such reamer
as to produce the most efficient performance. Each
nozzle holder assembly consists of two assemblies,
an injection nozzle holder and an injection nozzle.
b. The holder assembly positions the nozzle in the
cylinder head and provides a means of conducting
fuel received from the fuel injection pump to the
nozzle. The holder consists of a steel holder body,
two locating dowels, spindle, spindle spring, pres-
sure adjusting screw, adjusting screw locknut, gas-
kets, cap nut, and a nozzle retaining nut.
c. The nozzle assembly consists of a nozzle valve
anda nozzle body in which are located four spray
orifices equally spaced 90 degrees apart. The
nozzle valve is operated hydraulically within the
valve body by fuel delivered under pressure by the
fuel injection pump.
The nozzle is positioned on the
holder by two dowels whereby the four spray orifices
are fixed on a plane parallel to the piston top, and
the nozzle fuel duct is registered with the holder fuel
d. Fuel enters the nozzle holder fuel inlet passage,
passes through the holder fuel duct into the nozzle
fuel duct via an annular groove in the nozzle body,
and then into the pressure chamber above the nozzle
At the instant the fuel pressure in the
pressure chamber exceeds pressure exerted on
spindle and nozzle valve by the spindle spring, the
nozzle valve is lifted off its seat (popped) and fuel is
forced through orifices in the valve body end and into
the corresponding engine combustion chamber. The
nozzle valve is returned to its seat by pressure exer-
ted by the spindle spring when the fuel injection pump
has ceased to deliver fuel to the nozzle holder.
Refer to the Operator
Manual to remove the
and Organizational Maintenance
nozzle holder assembly.
Cleaning and Repair.
When more than one nozzle holder
assembly is disassembled, keep
parts of each separate. Complete
disassembly of the nozzle holder
assembly is seldom necessary. In
most cases, only disassembly and
cleaning of the nozzle valve body and
valve is required to place the nozzle
holder in good operational condition.
At completion of repair, check operation in accord-
ance with paragraph 14-40.
The nozzle valve and nozzle valve body are mated
parts, and must be kept together. If replacement of
either part is necessary, both parts must be re-
placed as matched sets. Remove, clean, and in-
spect the nozzle valve body and valve as follows:
a. Clamp nozzle holder body in a suitable holding
b. Remove cap nut (10) and gasket (11) from upper
end of nozzle holder (15). Loosen pressure adjusting
screw locknut (8) and turn pressure adjusting screw
(9) out sufficiently to release spring tension on spindle
spring (12). See figure 14-19.
Using a suitable socket or box wrench, loosen
and remove the nozzle retaining nut (5). Remove
the nozzle valve body (3) and nozzle valve (4) from
the retaining nut.
Start the nut back onto the holder
body to protect the lapped end of the holder body
Do not allow the solution to get on
the hands or body; use tweezers or the
basket method to handle the parts.
Withdraw the valve from the valve body and
it in a carbon and rust remover solution for
cleaning. Normally, the valve can easily be with-
drawn from the valve body, however, in some cases
it may be necessary to soak the valve body and valve
in carbon removing compound Type 2 per Federal
Specifications P-C-111 before the valve can be with-
drawn. For faster and better cleaning results, the
carbon removing compound should be heated to
approximately 200° F.
The parts generally can be
separated in two or three minutes; however, if
necessary they can be left in the solution longer.
After removing the parts from the solution, immedi-
ately place them in clean diesel fuel for neutralizing.
Always handle the parts carefully to protect the
The valve (4) and the seat in the valve body
(3) are originally ground to slightly different
angles to provide a line contact seat between the
Practically all the wear occurs in the
seat in the valve body.
The valve should never be
lapped to the seat in the valve body.
Using a magnifying glass, inspect condition
of seat in the valve body (3). If the seat is damaged
or worn in any way to prevent proper seating of the
valve, the nozzle assembly (1) must be replaced.
g. The outer surfaces of the valve body (15) may
be cleaned with a brass wire brush. Do not scrape
carbon from the surface around the orifices in tip of
valve body with any hard object as damage may re-
sult. Clean the four orifices in the valve body tip
Change 1 14-27