TM-9-2815-220-24
AVDS-1790 2CA, 2DA and 2DR Air-Cooled 12-Cylinder Diesel Engines
TECHNICAL MANUAL; UNIT, DIRECT SUPPORT AND GENERAL SUPPORT MAINTENANCE MANUAL FOR AVDS-1790 2CA, 2DA and 2DR Air-Cooled 12-Cylinder Diesel Engines
TM-9-2815-220-24 - Page 125 of 1563
TM 9-2815-220-24
ENGINE NOISY OPERATION
0015 00
MALFUNCTION 2:
Diesel knock ("ping," usually at low-idle speed).
PROBABLE CAUSE
CORRECTIVE ACTION
a. Manifold heater solenoid valves defective.
(1) Check solenoid operation as follows:
PROCEDURE
OBSERVATION
ANALYSIS
Evidence of action indicates
normal solenoid valve operation.
Press heater switch
intermittently "ON"
and "OFF".
Note audible "click" or opening
and closing valve action (by
touch) of both solenoid valves
(fuel supply and fuel return).
No audible "click" or action
indicates solenoid valve(s) is
defective.
Fuel flow indicates solenoid
valve is operating properly and
fuel filters are satisfactory.
With switch in "ON" position,
note fuel flow from tee opening
with each purge pump stroke.
No fuel or restricted flow
indicates manifold heater filter or
felt filters in solenoid valve are
restricted or clogged.
If fuel flow stops, solenoid valve
is closing properly.
To Check Solenoid
Valve and Fuel Filter:
Disconnect one fuel
tube from engine front
solenoid valve outlet
tee, operate purge
pump and press heater
switch "ON" and
"OFF".
With switch in "OFF" position
note that fuel flow stops.
If fuel flow continues, solenoid
valve is defective (stuck open).
PROCEDURE
OBSERVATION
ANALYSIS
Moderate flow indicates solenoid
valve is operating properly and
check valve is opening properly.
With switch in "ON" position,
note fuel flow from check valve
opening.
No fuel or restricted flow
indicates check valve stuck
closed or felt filters in solenoid
valve are restricted or clogged.
If fuel flow stops, solenoid valve
is closing properly.
To Check Return Fuel
Solenoid Valve and
Check Valve: Remove
fuel return solenoid
outlet tube after the
check valve at rear of
engine, operate purge
pump and press heater
switch "ON" and
"OFF".
With switch in "OFF" position
note that fuel flow stops.
If fuel flow continues, solenoid
valve is defective (stuck in open
position).
PROBABLE CAUSE
CORRECTIVE ACTION
a. (Continued)
Manifold heater solenoid
valves defective.
(2) Replace solenoid valve (WP 0087, Manifold
Heater Fuel Filter and Solenoid
Replacement).
WP 0015 00-3
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