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 167 of 836

TM 9-2320-272-24-4

5-25. CYLINDER HEAD REPAIR (Contd)

9.

10.

11.

12.

13.

14.

15.

Inspect valve seats (6) for wear, burrs, pits, and cracks. Replace cylinder head (1) if worn, pitted,

cracked, or burred. Mark valve seat (6) for resurfacing.

Inspect exhaust (14) and intake (15) valve guides for chips, cracks, burrs, breaks, and wear. Replace

cylinder head (1) if chipped, cracked, burred, broken, or worn.

Measure valve guide length (12) and inside diameter of valve guide bore (13). Refer to table 5-9,

Cylinder Head Wear Limits, for measurements. Replace cylinder head (1) if not within limits.

Inspect valves (3) for cracks, bends, and wear. Replace valve(s) (3) if cracked, bent, or worn.

Measure outside diameter of valve stem (9). Refer to table 5-9, Cylinder Head Wear Limits, for

measurements. Replace valve(s) (3) if not within limits.

Measure rim (10) thickness of valves (3). Refer to table 5-9, Cylinder Head Wear Limits, for

measurement. Replace valve(s) (3) if not within limits.

Inspect collet grooves (11) for wear.

a. Install new collets (7) in collet grooves (11).

b. If collets (7) fit loosely, replace valve(s) (3).

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