Dodge Dakota (R1). Manual — part 478
(6) Adjust the nose of the ram to align the pointer
with the SET mark on the scale of the tester and
tighten the hex nut.
(7) Slowly swing the weighted arm onto the push
rod.
(8) Rotate the cup by turning the handle at the
base of the tester clockwise one revolution every 2
seconds.
(9) Observe the leak-down time interval from the
instant the pointer aligns with the START mark on
the scale until the pointer aligns with the 0.125
mark. A normally functioning tappet will require
20-110 seconds to leak-down. Discard tappets with
leak-down time interval not within this specification.
REMOVAL
(1) Remove the air cleaner assembly and air in-let
hose.
(2) Remove cylinder head cover (Refer to 9 -
ENGINE/CYLINDER
HEAD/CYLINDER
HEAD
COVER(S) - REMOVAL).
(3) Remove rocker assembly and push rods (Refer
to 9 - ENGINE/CYLINDER HEAD/ROCKER ARM /
ADJUSTER ASSY - REMOVAL). Identify push rods
to ensure installation in original locations.
(4) Remove intake manifold (Refer to 9 - ENGINE/
MANIFOLDS/INTAKE MANIFOLD - REMOVAL).
(5) Remove yoke retainer and aligning yokes.
(6) Slide Hydraulic Tappet Remover/Installer Tool
C-4129-A through opening in cylinder head and seat
tool firmly in the head of tappet.
(7) Pull tappet out of bore with a twisting motion.
If all tappets are to be removed, identify tappets to
ensure installation in original location.
(8) If the tappet or bore in cylinder block is scored,
scuffed, or shows signs of sticking, ream the bore to
next oversize. Replace with oversize tappet.
CLEANING
Clean tappet with a suitable solvent. Rinse in hot
water and blow dry with a clean shop rag or com-
pressed air.
INSTALLATION
(1) Lubricate tappets with Mopar
t Engine Oil
Supplement or equivalent.
(2) Install tappets and push rods in their original
positions . Ensure that the oil feed hole in the side of
the tappet body faces up (away from the crankshaft).
(3) Install aligning yokes with ARROW toward
camshaft.
(4) Install yoke retainer. Tighten the bolts to 23
N·m (200 in. lbs.) torque. Install intake manifold
(Refer to 9 - ENGINE/MANIFOLDS/INTAKE MANI-
FOLD - INSTALLATION).
(5) Install rocker arms (Refer to 9 - ENGINE/CYL-
INDER HEAD/ROCKER ARM / ADJUSTER ASSY -
INSTALLATION).
(6) Install cylinder head cover (Refer to 9 -
ENGINE/CYLINDER
HEAD/CYLINDER
HEAD
COVER(S) - INSTALLATION).
(7) Install air cleaner assembly and air in-let hose.
(8) Start and operate engine. Warm up to normal
operating temperature.
CAUTION: To prevent damage to valve mechanism,
engine must not be run above fast idle until all
hydraulic tappets have filled with oil and have
become quiet.
Fig. 40 Leak-Down Tester
1 - POINTER
2 - WEIGHTED ARM
3 - RAM
4 - CUP
5 - HANDLE
6 - PUSH ROD
9 - 100
ENGINE 3.9L
AN
HYDRAULIC LIFTERS (CAM IN BLOCK) (Continued)
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).
PISTON MEASUREMENTS CHART
PISTON
A DIA = PISTON
BORE
SIZE
DIAMETER
DIAMETER
MIN.
MAX.
MIN.
MAX.
mm
(in.)
mm
(in.)
mm
(in.)
mm (in.)
A
99.280
99.294
99.308
99.320
(3.9087)
(3.9092)
(3.9098)
(3.9103)
B
99.294
99.306
99.320
99.333
(3.9092)
(3.9097)
(3.9103)
(3.9108)
C
99.306
99.319
99.333
99.345
(3.9097)
(3.9102)
(3.9108)
(3.9113)
D
99.319
99.332
99.346
99.358
(3.9102)
(3.9107)
(3.9113)
(3.9118)
E
99.332
99.344
99.358
99.371
(3.9107)
(3.9112)
(3.9118)
(3.9123)
DESCRIPTION
SPECIFICATION
PISTON PIN BORE
25.007 - 25.014 mm
(.9845 - .9848 in.)
RING GROOVE
HEIGHT
4.0309 - 4.0538 mm
(OIL RAIL)
(.1587 - .1596 in.)
RING GROOVE
HEIGHT
2.0294 - 2.0548 mm
(COMPRESSION
RAIL)
(.0799 - .0809 in.)
TOTAL FINISHED
594.6 ± 2 grams
WEIGHT
(20.974 ± .0706 ounces)
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
Fig. 41 Piston Measurements
1 - 62.230 mm
(2.45 IN.)
AN
ENGINE 3.9L
9 - 101
the connecting rod is centered in cylinder bore and at
BDC. Be careful not to nick crankshaft journals.
(7) After removal, install bearing cap on the mat-
ing rod.
CLEANING
Clean the piston and connecting rod assembly
using a suitable solvent.
INSPECTION
Check the connecting rod journal for excessive
wear, taper and scoring (Refer to 9 - ENGINE/EN-
GINE BLOCK/CONNECTING ROD BEARINGS -
STANDARD PROCEDURE).
Check the connecting rod for signs of twist or bend-
ing.
Check the piston for taper and elliptical shape
before it is fitted into the cylinder bore (Refer to 9 -
ENGINE/ENGINE BLOCK/PISTON & CONNECT-
ING ROD - STANDARD PROCEDURE).
Check the piston for scoring, or scraping marks in
the piston skirts. Check the ring lands for cracks
and/or deterioration.
INSTALLATION
(1) Be sure that compression ring gaps are stag-
gered so that neither is in line with oil ring rail gap.
(2) Before installing the ring compressor, be sure
the oil ring expander ends are butted and the rail
gaps located properly (Fig. 42) .
(3) Immerse the piston head and rings in clean
engine oil. Slide Piston Ring Compressor Tool C-385
over the piston and tighten with the special wrench
(part of Tool C-385). Be sure position of rings
does not change during this operation.
(4) Install connecting rod bolt protectors on rod
bolts. The long protector should be installed on the
numbered side of the connecting rod.
(5) Rotate crankshaft so that the connecting rod
journal is on the center of the cylinder bore. Be sure
connecting rod and cylinder bore number are the
same. Insert rod and piston into cylinder bore and
guide rod over the crankshaft journal.
(6) Tap the piston down in cylinder bore, using a
hammer handle. At the same time, guide connecting
rod into position on crankshaft journal.
(7) The notch, or groove, on top of piston must be
pointing toward front of engine. The larger chamfer
of the connecting rod bore must be installed toward
crankshaft journal fillet.
(8) Install rod caps. Be sure connecting rod, con-
necting rod cap, and cylinder bore number are the
same. Install nuts on cleaned and oiled rod bolts and
tighten nuts to 61 N·m (45 ft. lbs.) torque.
(9) Install the oil pan (Refer to 9 - ENGINE/LU-
BRICATION/OIL PAN - INSTALLATION).
(10) Install
the
cylinder
head
(Refer
to
9
-
ENGINE/CYLINDER HEAD - INSTALLATION).
(11) Install the engine into the vehicle (Refer to 9 -
ENGINE - INSTALLATION).
PISTON RINGS
STANDARD PROCEDURE - PISTON RING
FITTING
(1) Measurement of end gaps:
(a) Measure piston ring gap 2 in. from bottom of
cylinder bore. An inverted piston can be used to
push the rings down to ensure positioning rings
squarely in the cylinder bore before measuring.
(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 in.). The second compression ring
gap
should
be
between
0.508-0.762
mm
(0.020-0.030 in.). The oil ring gap should be 0.254-
1.270 mm (0.010-0.050 in.).
(c) Rings with insufficient end gap may be prop-
erly filed to the correct dimension. Rings with
excess 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
according to instructions in the package. It is not
necessary 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
Installation Tool C-4184. The compression rings
Fig. 42 Proper Ring Installation
1 - OIL RING SPACER GAP
2 - SECOND COMPRESSION RING GAP OIL RING RAIL GAP
(TOP)
3 - OIL RING RAIL GAP (BOTTOM)
4 - TOP COMPRESSION RING GAP
9 - 102
ENGINE 3.9L
AN
PISTON & CONNECTING ROD (Continued)
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” (Fig. 43) (Fig. 45).
(c) Using a ring installer, install the top com-
pression ring with the chamfer facing up (Fig. 44)
(Fig. 45). 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 in.) for the compression rings. The
steel rail oil ring should be free in groove, but
should not exceed 0.246 mm (0.0097 in.) side clear-
ance.
(e) Pistons with insufficient, or excessive, side
clearance should be replaced.
(3) Orient the rings:
(a) Arrange top compression ring 90° counter-
clockwise from the oil ring rail gap (Fig. 46) .
(b) Arrange second compression ring 90° clock-
wise from the oil ring rail gap (Fig. 46) .
Fig. 43 Second Compression Ring Identification
(Typical)
1 - SECOND COMPRESSION RING (BLACK CAST IRON)
2 - CHAMFER
3 - TWO DOTS
Fig. 44 Top Compression Ring Identification
(Typical)
1 - TOP COMPRESSION RING (GRAY IN COLOR)
2 - CHAMFER
3 - ONE DOT
Fig. 45 Compression Ring Chamfer Location
(Typical)
1 - CHAMFER
2 - TOP COMPRESSION RING
3 - SECOND COMPRESSION RING
4 - PISTON
5 - CHAMFER
Fig. 46 Proper Ring Installation
1 - OIL RING SPACER GAP
2 - SECOND COMPRESSION RING GAP OIL RING RAIL GAP
(TOP)
3 - OIL RING RAIL GAP (BOTTOM)
4 - TOP COMPRESSION RING GAP
AN
ENGINE 3.9L
9 - 103
PISTON RINGS (Continued)
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