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 120 of 1563
TM 9-2815-220-24
ENGINE ROUGH OPERATION
0014 00
MALFUNCTION 1:
(Continued)
Engine misfires (more noticeable at idle operation).
PROBABLE CAUSE
CORRECTIVE ACTION
e. (Continued)
No valve rocker clearance.
(1) Locate faulty cylinder as follows:
PROCEDURE
OBSERVATION
ANALYSIS
Fuel "Shorting" Method:
Check all cylinders, one at a time.
Loosen fuel injector
tube fitting at nozzle
end sufficiently to
allow fuel leakage.
Note cylinder on which no
change in engine operation
occurs, knock disappears or
decreases, and/or engine
roughness or misfire still exists.
Indicates faulty cylinder,
defective nozzle, tight rocker arm,
worn valve or hydrostatically
damaged connecting rod.
High Pressure Fuel Check:
Remove one engine cover on each side of engine for access
to fuel injector nozzle tube fittings.
Crank engine with fuel switch "ON" or start engine and
operate at idle speed.
High-pressure fuel spray
pulsations at nozzle fitting.
Fuel injection pump action is
normal.
Loosen fuel injector
tube fitting at nozzle
end sufficiently to allow
fuel leakage.
No fuel spray pulsations noted
at nozzle fitting.
Fuel injection pump deficiency.
Cylinder Compression Test Method:
Perform Cylinder
Compression Test
(WP 0033, Cylinder
Compression Test).
Note cylinder with low pressure
(below 330 psi at 140-180
cranking rpm).
Indicates faulty cylinder,
damaged rings, piston, valve,
connecting rod or tight rocker arm
(no valve clearance).
PROBABLE CAUSE
CORRECTIVE ACTION
e. (Continued) No valve rocker clearance.
(2) Adjust valve to proper clearance
(WP 0034, Intake and Exhaust Valve
Clearance Adjustment).
(1) Locate faulty cylinder as above.
f.
Intake or exhaust valve failure (burned,
worn or damaged).
(2) Inspect, repair or replace valve and/or
cylinder (WP 0133, Cylinder Assembly
Replacement).
WP 0014 00-2
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