Dodge RAM TRUCK 1500 1995 Service Manual page 914

PISTON PIN BORE DIAMETER
\ 25.007-25.015 m m
RING GROOVE HEIGHT
OIL RAIL GROOVE 4.0309 - 4.0538 mm-***
(J 587-.1596 IN.)
COMPRESSION RAIL GROOVE - « - J
2,0294 - 2.0548 m m
(.0799 - .0809 IN.)
TOTAL WEIGHT (FINISHED)
594.6 ± 2 GRAMS
PISTON
SIZE
A D1A = PiSTC M DIAMETER BORE DIAMETER
PISTON
SIZE
MIN. mm (IN.) MAX.
mm
(IN.)
MSN.
mm
(IN.) MAX. mm (IN.)
A 99.280 (3.9087) 99.294 (3.9092) 99.306 (3.9097)
99.319(3.9102)
B 99.294 (3.9092) 99.306 (3.9097) 99.319(3.9102) 99.332 (3.9107)
C 99.306 (3.9097) 99.319(3.9102)
99.332 (3.9107) 99.344 (3.9112)
D 99.319(3.9102) 99.332 (3.9107) 99.344(3.9112)
99.357(3.9117)
E 99.332 (3.9107) 99.344(3.9112) 99.357(3.9117) 99.370(3.9122)
J9509-80
Fig. 4 Piston Measurements
FITTING PISTONS
Piston and cylinder wall must be clean and dry.
Specified clearance between the piston and the cylin­
der wall is 0.013-0.038 mm (0.0005-0.0015 inch).
Piston diameter should be measured at the top of
skirt, 90° to piston pin axis. Cylinder bores should be
measured halfway down the cylinder bore and trans­
verse to the engine crankshaft center line.
Pistons and cylinder bores should be measured at
normal room temperature, 21°C (70°F).
FITTING RINGS
(1) Measurement of end gaps:
(a) Measure piston ring gap 2 inches from bot­
tom of cylinder bore. An inverted piston can be
used to push the rings down to ensure positioning
rings squarely in the cylinder bore before measur­
ing.
(b) Insert feeler gauge in the gap. The top com­
pression ring gap should be between 0.254-0.508
mm (0.010-0.020 inch). The second compression
ring gap should be between 0.508-0.762 mm (0.020-
0.030 inch). The oil ring gap should be 0.254-1.270
mm (0.010-0.050 inch).
(c) Rings with insufficient end gap may be prop­
erly filled to the correct dimension. Rings with ex­
cess gaps should not be used.
(2) Install rings and confirm ring side clearance:
(a) Install oil rings being careful not to nick or
scratch the piston. Install the oil control rings ac­
cording to instructions in the package. It is not nec­
essary to use a tool to install the upper and lower
rails. Insert oil rail spacer first, then side rails.
(b) Install the second compression rings using In­
stallation Tool C-4184. The compression rings must
be installed with the identification mark face up
(toward top of piston) and chamfer facing down. An
identification mark on the ring is a drill point, a
stamped letter O, an oval depression or the word
TOP (Figs. 5 and 7).
S E C O N D C O M P R E S S I O N R I N G
(BLACK CAST JftONJ
CHAMFER
T W O
DOTS
J9009-46
Fig. 5 Second Compression Ring Identification
(Typical)
(c) Using a ring installer, install the top compres­
sion ring with the chamfer facing up (Fig. 6). An
identification mark on the ring is a drill point, a
stamped letter O, an oval depression or the word
TOP facing up.
> C O M P R E S S I O N R I N G
(GRAY I N COLOR)
I
O N E
DOT
Kraal
H P
J9009-48
Fig. 6 Top Compression Ring Identification (Typical)
(d) Measure side clearance between piston ring
and ring land. Clearance should be 0.074-0.097 mm
(0.0029-0.0038 inch) for the compression rings. The
steel rail oil ring should be free in groove, but
should not exceed 0.246 mm (0.0097 inch) side
clearance.
(e) Pistons with insufficient or excessive side
clearance should be replaced.
(3) Arrange ring gaps 180° apart as shown in Fig.
8.