Dodge Dakota Sport 2001 Service Manual page 1130

AN
PISTON & CONNECTING ROD
DESCRIPTION
The pistons are made of aluminum and have three
ring grooves, the top two grooves are for the compres-
sion rings and the bottom groove is for the oil control
ring. The connecting rods are forged steel and are
coined prior to heat treat. The piston pins are press
fit.
STANDARD PROCEDURE—PISTON FITTING
Check the cylinder block bore for out-of-round,
taper, scoring, or scuffing.
Check the pistons for taper and elliptical shape
before they are fitted into the cylinder bore (Fig. 41).
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 in.) at
21°C (70°F).
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).
Fig. 41 Piston Measurements
1 - 62.230 mm
(2.45 IN.)
PISTON MEASUREMENTS CHART
PISTON A DIA = PISTON
SIZE DIAMETER
MIN.
mm
(in.)
A 99.280
(3.9087)
B 99.294
(3.9092)
C 99.306
(3.9097)
D 99.319
(3.9102)
E 99.332
(3.9107)
DESCRIPTION
PISTON PIN BORE
RING GROOVE
HEIGHT
(OIL RAIL)
RING GROOVE
HEIGHT
(COMPRESSION
RAIL)
TOTAL FINISHED
WEIGHT
REMOVAL
(1) Remove the engine from the vehicle (Refer to 9
- ENGINE - REMOVAL).
(2) Remove the cylinder head (Refer to 9 -
ENGINE/CYLINDER HEAD - REMOVAL).
(3) Remove the oil pan (Refer to 9 - ENGINE/LU-
BRICATION/OIL PAN - REMOVAL).
(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 each connecting rod and connecting rod
cap is 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 the
assemblies from the engine, rotate crankshaft so that
ENGINE 3.9L
BORE
DIAMETER
MAX. MIN.
mm mm mm (in.)
(in.) (in.)
99.294 99.308
(3.9092) (3.9098) (3.9103)
99.306 99.320
(3.9097) (3.9103) (3.9108)
99.319 99.333
(3.9102) (3.9108) (3.9113)
99.332 99.346
(3.9107) (3.9113) (3.9118)
99.344 99.358
(3.9112) (3.9118) (3.9123)
SPECIFICATION
25.007 - 25.014 mm
(.9845 - .9848 in.)
4.0309 - 4.0538 mm
(.1587 - .1596 in.)
2.0294 - 2.0548 mm
(.0799 - .0809 in.)
594.6 ± 2 grams
(20.974 ± .0706 ounces)
9 - 101
MAX.
99.320
99.333
99.345
99.358
99.371