c. Inspect spring for cracks, damage and signs of
d. Replace unserviceable parts.
11-15. Oil Pressure Relief Valve, Reassembly and
a. Reassembly and Installation. Reassemble and
install the oil pressure relief valve in reverse numerical
sequence as illustrated in figure 11-16.
b. Adjustment. Adjustment of the oil pressure
relief valve is accomplished by the removal and
installation of washers (3, fig. 11-16) behind spring (4).
(1) With engine at operating temperature, the
recommended pressure at idle speed is 5 to 10 psi (0.35
to 0.70 kg/cm2).
(2) With engine at operating temperature the
recommended pressure at full throttle is 30 to 40 psi (2.1
to 2.8 kg/cm2).
(3) To increase pressure, add washers (3).
Add washers, one at a time, and check pressure. If after
Figure 11-16. Oil pressure relief valve, disassembly and
installing four washers, pressure is still low, replace
(4) To decrease pressure, remove washers.
11-14. Oil Pressure Relief Valve, Cleaning,
Remove washers, one at a time, and check pressure. If
Inspection and Repair
all washers are removed and pressure is still high,
a. Clean all metal parts in cleaning compound,
solvent (Fed. Spec. P-D-680) and dry thoroughly.
b. Inspect valve for dents, wear and damage.
Section III. PISTONS AND CONNECTING RODS
(1) Refer to paragraph 2-22 and remove the
engine from the truck.
a. The connecting rods are precision ground and
(2) Refer to paragraph 11-7 and remove the
rifle drilled. They receive the thin-wall precision type
bearing shells to mount to the crankshaft.
(3) Refer to TM 10-3930-630-12 and remove
b. The aluminum pistons have four rings, two
the cylinder head.
compression rings, one scraper ring and one three piece
(4) Use a ridge cutting tool and remove ridge
oil control ring.
at top of piston bores.
(5) Refer to figure 11-17 and remove rod
11-17. Piston and Connecting Rods, Removal and
bearing cap nuts and connecting rod bearing caps and
(6) Slide piston and connecting rod up out
the top of the engine crank case.