Cleaning/Inspection-continued - TM-9-2815-224-34-P0175

TM 9-2815-224-34&P

Piston and Connecting Rod Maintenance Instructions (Cont)

(7) Measure diameter of piston skirt (3) and check for roundness.

Diameter must not be less than 4.829-in. (122,6 mm) at any one

point.

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(8) With cylinder liner (4) installed in

engine block (5), Soldier A holds

piston skirt (3) upside down in liner.

Soldier B attaches spring scale to

feeler gage set and checks clearance

in four places 90 degrees apart.

(9) Select feeler gage thickness that will

require a pull of 6 pounds (2.7 kg).

Clearance will be 0.001-in. (0.25 mm)

greater than feeler gage thickness

when it is withdrawn with a pull of

6 pounds (2.7 kg). Clearance must not

exceed 0.012-in. (0.3 mm).

(10) Insert piston rings (6), one at a time inside

cylinder liner (4) far enough to be in area of ring

travel 2 to 3 in. deep. Use piston skirt to

position ring parallel with top of cylinder liner.

(11) Measure ring gap (7) with feeler gage. Three

compression rings should have a gap of 0.025 to

0.045 in. (0.63 to 1.1 mm). Top compression ring

is marked with two punch marks, middle

compression ring is marked with one punch

mark and bottom compression ring is not punch

marked. Two oil rings (upper slotted) should

have a gap of 0.007 to 0.017 in. (0.2 to 0.4 mm).

Two oil rings (lower) should have a gap of

0.010 to 0.025 in. (0.25 to 0.63 mm).

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