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 48 of 836
TM 9-2320-272-24-4
5-7. CYLINDER LINERS AND BLOCK MAINTENANCE (Contd)
22.
Install main bearing caps (2) in engine block (1) without crank or bearing shells.
23.
Measure main bearing bore diameter (3) horizontally, vertically, and diagonally with telescoping
gauge (4). Ensure bore diameter does not exceed 4.75 in. (120-663 mm).
NOTE
Pipe plugs, cup plugs, and suction flange plate are installed at this
time to keep passages clean. Wrap pipe plug threads with sealing
tape to prevent leakage.
24.
Install two cup plugs (9) in engine block (1).
25.
Install four pipe plugs (8) in block (1) and tighten according to table 5-6.
26.
Install eight pipe plugs (10) in block (1) and tighten according to table 5-6.
27.
Install new gasket (14) and suction flange plate (13) on engine block (1) with two new
lockwashers (12) and screws (11). Tighten screws (11) 10-15 lb-ft (14-20 N•m).
Table 5-6. Engine Block Pipe Plug Torque.
PIPE PLUG SIZE
1/8 in.
15
(20)
1/4 in.
30
(41)
3/8 in.
35
(47)
1/2 in.
45
(61)
3/4 in.
60
(81)
1-1/4 in.
75
(102)
1-1/2 in.
90
(122)
MINIMUM
LB-FT
(NM
MAXIMUM
LB-FT
(N•M)
20
(27)
35
(47)
45
(61)
55
(75)
70
(95)
85
(115)
100
(136)
NOTE
Most attempts to hone or deglaze cylinder liners provide worse
results than leaving them “as is”. Experience and laboratory
results indicate that liners do not need to be honed, rotated, or
deglazed to provide proper setting.
It is recommended that cylinder liners be inspected before
cleaning so defects can be clearly noted.
Inspect cylinder liners closely for any of the metal conditions
illustrated. If one liner has failed, then other liners in the same
engine are likely to have early signs of the same type of failure.
28.
Check cylinder liner (5) for scoring or vertical grooving (6) on the inside diameter indicating heavy
metal-to-metal contact of piston to cylinder liner (5). If scoring or vertical grooving (6) is present, tag
cylinder liner for replacement.
29.
Check cylinder liner (5) for cracks (7) indicated by magnetic detection. If cracks (7) are present, tag
cylinder liner (5) for replacement.
5-42
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