TM-9-2815-237-34 HMMWV Engine Direct Support & General Support Maintenance Manual Download
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TM 9-2815-237-34 2-21. CYLINDER HEAD AND VALVE REPAIR (Cont’d) 9. Install valve (2) in valve guide (4) from which it was removed. CAUTION Clearance must be 0.001-0.003 in. (0.026-0.076 mm). Excessive valve stem clearance will cause excessive oil consumption and may cause valve breakage. NOTE ● Intake and exhaust valves are available with 0.0035 in. (0.089 mm) and 0.0137 in. (0.349 mm) oversize stems. ● If valve stem clearance is more than 0.0027 in. (0.068 mm), valve guide must be reamed to next size and oversized valve installed. If unable to produce clearance with oversize valve, replace cylinder head. 10. Using dial indicator, measure valve stem clearance. Dial indicator must contact valve stem (1) just above valve guide (4) and at a right angle to the valve stem (1). Drop valve (2) approximately 1/16 in. (1.6 mm) off valve seat (3) and move side-to-side when taking measurement. 11. Repeat steps 9 and 10 for remaining valves (2) and valve guides (4). 12. Inspect cold start advance switch (6) and engine temperature sending unit (5) for damage. Replace if damaged. d. Refacing Valves 1. Using valve face grinding machine, grind valve face (7) on all valves (2) to 45”. 2. Maintain a minimum of 1/32 in. (0.80 mm) margin (8) on all valves (2). If margin falls below specifications, replace valve. e. Grinding Valve Seats 1. Using valve seat grinding kit, grind all valve seats (3) to 46°. NOTE If valve seat width exceeds specifications, valve seat width must be narrowed. 2. Measure width of intake valve seats (3). Valve seats (3) must not be wider than 1/16 in. (1.53 mm). 3. Measure width of exhaust valve seats (3). Valve seats (3) must not be wider than 3/32 in. (2.36 mm). 2-66