Dodge RAM TRUCK 1500 1995 Service Manual page 885

from each other, causing the piston to assume a more
nearly-round shape.
All pistons are machined to the same weight, re­
gardless of size, to maintain piston balance.
The piston pin rotates In the piston only and is re­
tained by the press interference fit of the piston pin
In the connecting rod.
REMOVAL
(1) Remove the engine from the vehicle.
(2) Remove the cylinder head.
(3) Remove the oil pan.
(4) Remove top ridge of cylinder bores with a reli­
able ridge reamer before removing pistons from cyl­
inder block. Be sure to keep tops of pistons covered
during this operation.
(5) Be sure the connecting rod and connecting rod
cap are Identified with the cylinder number. Remove
connecting rod cap. Install connecting rod bolt guide
set on connecting rod bolts.
(6) Pistons and connecting rods must be removed
from top of cylinder block. When removing piston and
connecting rod assemblies, rotate crankshaft to cen­
ter the connecting rod in the cylinder bore and at
BDC. Be careful not to nick crankshaft journals.
(7) After removal, install bearing cap on the mat­
ing rod.
INSPECTION
Check the crankshaft connecting rod journal for ex­
cessive wear, taper and scoring.
Check the cylinder block bore for out-of-round,
taper, scoring and scuffing..
Check the pistons for taper and elliptical shape be­
fore they are fitted into the cylinder bore (Fig. 18).
FiTTiffs
pmwmm
Piston and cylinder wall must be clean and dry.
Specified clearance between the piston and the cylin­
der wall Is 0.018-0.038 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, 2PC (70°F).
FITTING mmm
(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
PISTON PIN BORE DIAMETER
25.007- 25.015 mm
.9848 IN.]
62.230 m m
|2.45
I N :
I
RING GROOVE HEIGHT
OIL RAIL GROOVE 4.0309 - 4.0538 mrn^
(.1587- .1596 IN.)
COMPRESSION RAIL GROOVE -
2.0294-2.0548 mm
(.0799 - .0809 IN.)
TOTAL WEIGHT (FINISHED)
594.6 ±2 GRAMS
PISTON
SIZE
ADMUP1STC M WAMETCR BORED AMBER
PISTON
SIZE WIN. mm (IN.) MAX. mm (IN.)
MIN. 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. 13 Piston Measurements
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 filed 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. 14 and 16.
(c) Using a ring installer, install the top compres­
sion ring with the chamfer facing up (Fig. 16). An
identification mark on the ring is a drill point, a
stamped letter O, an oval depression or the word
TOP facing up.
(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