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 196 of 836
TM 9-2320-272-24-4
5-28. CYLINDER LINERS AND BLOCK MAINTENANCE (Contd)
d. Cylinder Liner and Engine Block Cleaning and Inspection
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
5-190
WARNING
• Drycleaning solvent is flammable and toxic. Do not use near an
open flame and always have a fire extinguisher nearby when
solvents are used. Use only in well-ventilated places, wear
protective clothing, and dispose of cleaning rags in approved
container. Failure to do this may result in injury or death to
personnel and/or damage to equipment.
• Eyeshields must be worn when cleaning with compressed air.
Compressed air source will not exceed 30 psi (207 kPa). Failure
to do so may result in injury to personnel.
CAUTION
• Do not allow debris to fall into crankshaft oil holes. Damage to
crankshaft bearings could result.
• Do not remove stock material from cylinder liner seating
surface when cleaning. Machined tolerances are critical and
premature engine failure will result if material is removed.
Cover crankshaft oil holes (6) with clean rags.
Clean all expansion plug holes of engine block (2) with drycleaning solvent. Dry with compressed
air.
Clean sealing surfaces (3), (4), and (5) of engine block (2) with crocus cloth and drycleaning solvent.
Inspect sealing surfaces (3), (4), and (5) for cracks, pits, scores, and excessive wear. Replace engine
block (2) if cracked, pitted, scored, or excessively worn.
Measure inside diameter of sealing surface (4). Replace engine block (2) if inside diameter exceeds
5.2342 in. (132.949 mm).
Clean all oil draining and water cooling passage bores with brush and drycleaning solvent. Dry with
compressed air.
CAUTION
Engine block deck can be resurfaced twice in increments of
0.010 in. (0.254 mm). Do not exceed 0.020 in. (0.508 mm) when
resurfacing or damage to equipment will result.
Using straight edge and feeler gauge, inspect engine block (2) deck for warping. Replace engine
block (2) if warping exceeds 0.008 in. (0.203 mm). Notify your supervisor.
Install seven main bearing caps (8) on engine block (2) with fourteen screws (9). Tighten
screws (9) 130 lb-ft (176 N•m).
Using bore gauge, measure inside diameter of main bearing bore (10). Record measurement.
Replace main bearing (7) if inside diameter exceeds 3.8632 in. (98.125 mm).
Using bore gauge, measure inside diameter of camshaft bore (12). Replace bushing (13) if inside
diameter exceeds 2.367 in. (60.12 mm).
Measure inside diameter of tappet bore (11). Replace engine block (2) if inside diameter exceeds
0.632 in. (16.05 mm).
NOTE
Cylinder liners should be inspected before cleaning so defects can
be clearly noted.
Check cylinder liner (1) for cracks, scoring, or vertical grooves. Replace cylinder liner (1) if cracked,
scored, or vertical grooves are present.
Check cylinder liner (1) for pits and eroded surfaces. Replace cylinder liner (1) if pitted or eroded.
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