TM-9-2320-272-24-4
TRUCK, 5-TON, 6X6, M939, M939A1, AND M939A2 SERIES TRUCKS (DIESEL)
TECHNICAL MANUAL; UNIT, DIRECT SUPPORT, AND GENERAL SUPPORT MAINTENANCE MANUAL; VOLUME 4 OF 4
JUNE 1998
TM-9-2320-272-24-4 - Page 16 of 836
TM 9-2320-272-24-4
5-3. CYLINDER HEAD REPAIR (Contd)
19.
Install injector (18) in cylinder head (3) with washer (19), clamp (10), and two
screws (11). Tighten alternately in 4 lb-ft (5.4 N-m) steps to 10-12 lb-ft (14-16 N-m).
20.
Measure protrusion of injector tip (8) with gauge block. Protrusion should be 0.060-0.070 in.
(1.52-1.78 mm). If not, mark sleeve (9) for replacement (para. 5-6).
21.
Air-test fuel inlet passage (4) and fuel outlet passage (5) for leakage and cracks.
a. Install two O-rings (6), plate (2), and two screw-assembled lockwashers (1).
b. Install pipe adapter (151, pipe extension (16), and air pressure gauge (17) into fuel outlet
passage (5).
c. Install air hose adapter (121, air pressure control valve (13), and air hose (141 into fuel inlet
passage (4).
d. Open air pressure control valve (13) and apply air pressure until air pressure gauge (17) reads
80-100 psi (550-690 pKa), then close valve (13).
e. Observe air pressure gauge (17). If pressure drops before fifteen seconds, replace cylinder head (3).
f. If air pressure holds for fifteen seconds, cylinder head (3) is serviceable.
NOTE
Replace pipe plugs in fuel passages of cylinder head after removal
of test adapters.
22.
Remove air pressure gauge (17). pipe extension (16), and pipe adapter (15).
23.
Remove air hose adapter (12), air pressure control valve (13), and air hose (14) from fuel inlet
passage (4)
24.
Inspect four crosshead guides (7) in accordance with instructions in para. 2-15.
25.
Check outside diameter of four crosshead guides (7) using micrometer or dial gauge. If outside
diameter is less than 0.432 in. (10.97 mm), mark guide (7) for replacement.
26.
Check four crosshead guides (7) for correct height. If height is not 1.860-1.880 in. (47.24-47.75 mm),
mark guide (7) for replacement.
27.
Check four crosshead guides (7) for straightness. If guide (7) is not straight, replace guide (7)
(subtask d, step 1).
5-10
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