(4) Use handle end of hammer to force piston
(1) Insert a 1/2 inch width feeler gage (0.003
through compressor and into cylinder (fig.
inch thickness) full length in the cylinder
14). To prevent damage to piston rings,
always keep compressor tight against
(2) Insert piston halfway down the bore and
block while forcing piston into cylinder.
hook scale in end of feeler gage.
(5) Place upper half of connecting rod
(3) Pull on scale to lift feeler gage out slowly
bearing in rod, making certain that small
(fig. 18). If the fit is correct, scale should
forward ear fits in the machined grooves
register pull of 5 to 10 pounds.
in the rods.
(4) Test bore for roundness by inserting feeler
(6) Oil crankshaft journal with OE, and install
gage in several places around cylinder
lower half of connecting rod bearing in
walls Any variation in roundness will be
cap, and install cap in connecting rod.
noted by an increased or decreased
Tighten rod nuts to 35 to 40 foot-pounds
weight on scale as feeler gage is pulled
(7) Install cylinder head (TM 10-3930-222-
(5) Measure cylinder bores carefully. If rings
are good and engine is known to have
(8) Install oil pan (par. 14c).
definite power loss or excessive fuel
consumption, and compression tests and
careful examination eliminate valves as
the source of trouble, reboring of cylinders
a. Inspection. With engine out and all assemblies
for oversized pistons may be necessary
removed, inspect the cylinder block for:
(fifth echelon only). As a general rule,
(1) Cracks, breaks, and leaks.
cylinders will be rebored if taper exceeds
(2) Inspect bore for scoring, wear, and out-of-
0.007 inch. If taper is not excessive, the
use of new rings may correct the trouble.
b. Overhaul. If bore is out-of-round and inspection
When selecting new pistons, check
shows much wear, it will be necessary to have the block
diameter carefully with micrometer as
rebored (fifth echelon).
shown in figure 19.
f. Assembly and Installation.
Heat Control Shaft and Valve
(1) Oil cylinder wall and flood piston with OE.
(2) Make sure that ring gaps are spaced
(1) Remove heat control assembly (TM 10-
equally about circumference of piston;
then compress rings with ring compressor.
(2) Separate exhaust manifold from intake
circumference as compressor is closed on
(3) Cut spot welds that attach valve to heat
rings to allow rings to close evenly.
control shaft and slide shaft from
(3) Because connecting rods are offset and
must be installed in proper bore, check
(4) Remove valve from exhaust manifold.
number stamped on connecting rod with
(5) Remove bushings from manifold.
corresponding number on cylinder bore.
b. Cleaning and Repair.
Install piston rod in proper cylinder with oil
(1) Wash all parts in SD.
squirt hole toward valve side of engine
(2) Replace defective parts as authorized.
(the slotted side of the piston away from
the valve side). Crankshaft journal for the
(1) Reverse procedures in a above.
connecting rod should be installed at
(2) Spotweld valve to shaft.
bottom dead center.