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 28 of 836
TM 9-2320-272-24-4
5-5. VALVE SEAT INSERTS MAINTENANCE
THIS TASK COVERS:
a. Removal
b. Gauging
c. Counterboring
d. Cleaning
e. Installation
INITIAL SETUP:
APPLIABLE MODELS
M939/Al
MATERIALS/PARTS
Valve seat inserts (Appendix D, Item 708)
SPECIAL TOOLS
Valve seat insert tool (Appendix E, Item 158)
Cutter seat (Appendix E Item 34)
Drycleaning solvent (Appendix C, Item 71)
REFERENCES (TM)
TM 9-2320-272-24P
Valve guide arbor (mandrel set) (Appendix E,
Item 154)
EQUIPMENT CONDlTlON
Tool driver (Appendix E, Item 140)
Cylinder head disassembled (para. 5-3).
Valve seat insert staking tool (Appendix E,
Item 157)
GENERAL SAFETY INSTRUCTIONS
Valve seat insert extractor (Appendix E,
When cleaning with compressed air, wear
Item 156)
eyeshields and ensure source pressure does not
TOOLS
exceed 30 psi (207 kPa).
Keep fire extinguisher nearby when using
General mechanic’s tool kit (Appendix E, Item 1)
drycleaning solvent.
Inside micrometer (Appendix E, Item 82)
Drycleaning solvent is flammable and toxic. Do
Outside micrometer (Appendix E, Item 80)
not use near an open flame.
Vernier calipers (Appendix E, Item 159)
Depth gauge (Appendix E, Item 81)
Brush
Electric drill
1.
Pull valve seat insert (3) from bore (2) on cylinder head (1) with valve seat insert extractor tool.
CAUTION
Each replacement valve seat insert outside diameter and
thickness must be measured and compared to relating valve seat
insert counterbore in the cylinder head before counterboring.
These measurements will prevent over-boring and damage to the
cylinder head.
1.
Measure outside diameter of valve seat insert (3) using micrometer. Record reading and compare
with specifications in table 5-2.
2.
Measure thickness of valve seat insert (3). Record reading and compare with specifications in table
5-2.
3.
Measure valve seat counterbore (4) depth (5) with depth micrometer. Record reading and compare to
specifications in table 5-2.
4.
Measure valve seat insert counterbore (4) inside diameter with inside micrometer. Record reading
and compare to specifications in table 5-2.
5-22
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