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Chrysler 300M, Dodge Interpid. Manual - part 251

FLEX PLATE

REMOVAL

(1) Remove the transaxle. (Refer to 21 - TRANS-

MISSION/TRANSAXLE/AUTOMATIC

42LE

REMOVAL)

(2) Remove flex plate attaching bolts.
(3) Remove the flex plate (Fig. 79).

INSTALLATION

(1) Position flex plate with backing plate on the

crankshaft (Fig. 79).

(2) Apply Mopar

t Lock & Seal Adhesive to the flex

plate bolts.

(3) Install flex plate bolts (Fig. 79). Tighten bolts

to 95 N·m (70 ft. lbs.).

(4) Install the transaxle. (Refer to 21 - TRANS-

MISSION/TRANSAXLE/AUTOMATIC

42LE

INSTALLATION)

PISTON & CONNECTING ROD

DESCRIPTION

NOTE: Valve reliefs were removed from the pistons
for the 2003MY. It is possible when ordering a ser-
vice piston/rod assembly that valve reliefs are
present. These may be used in the engine, and will
not affect engine operation.

The pistons are made of a high strength aluminum

alloy. Top land height has been decreased to reduce
emissions. Piston skirts are coated with a solid lubri-
cant for scuff resistance. Connecting rod is forged
steel with a squirt hole and attaches to the piston
with a full floating pin retained by lock rings.

STANDARD PROCEDURE - FITTING PISTONS

The pistons are machined to two different weight

specifications and matched to rods based on weight.
All piston and rod assemblies weigh the same to
maintain engine balance.

Piston and cylinder wall must be clean and dry.

Piston diameter should be measured 90 degrees to
piston pin at size location shown in (Fig. 80). Cylin-
der bores should be measured halfway down the cyl-
inder bore and transverse to the engine crankshaft
center line (Refer to 9 - ENGINE - SPECIFICA-
TIONS). Pistons and cylinder bores should be
measured at normal room temperature, 70°F
(21°C).

REMOVAL

(1) Remove the cylinder heads (Refer to 9 -

ENGINE/CYLINDER HEAD - REMOVAL)

Fig. 78 Rear Crankshaft Seal Retainer Alignment

1 - SEAL RETAINER
2 - SPECIAL TOOLS 8225

Fig. 79 FLEX PLATE

1 - FLEX PLATE
2 - BOLT (QTY. 8)
3 - BACKING PLATE

ENGINE

9 - 51

CRANKSHAFT REAR OIL SEAL RETAINER (Continued)

(2) Remove the oil pan. (Refer to 9 - ENGINE/LU-

BRICATION/OIL PAN - REMOVAL)

(3) 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. Pistons and con-
necting rods must be removed from top of cyl-
inder

block.

When

removing

piston

and

connecting rod assemblies from the engine,
rotate crankshaft so that each connecting rod
is centered in cylinder bore.

(4) Inspect connecting rods and connecting rod

caps for cylinder identification. Identify them if nec-
essary (Fig. 81).

(5) Remove connecting rod cap. Install protectors

on connecting rod bolts (Fig. 82). Push each piston
and rod assembly out of cylinder bore.

NOTE: Be careful not to nick crankshaft journals.

(6) After removal, install bearing cap on the mat-

ing rod.

INSTALLATION

(1) Install the piston rings. (Refer to 9 - ENGINE/

ENGINE

BLOCK/PISTON

RINGS

INSTALLA-

TION)

NOTE: The connecting rod bearing cap bolts must
be examined before reuse. If the threads are necked
down, the bolts must be replaced.

(2) Check connecting rod bolts for necking by hold-

ing a scale or straight edge against the threads. If all
threads do not contact the scale, the bolt must be
replaced (Fig. 83).

Fig. 80 Piston Measurements

Fig. 81 Connecting Rod to Cylinder Identification

1 - CYLINDER NUMBER

Fig. 82 Connecting Rod Guides and Crankshaft

Protectors

1 - COVER ROD BOLTS WITH A SUITABLE COVERING WHEN
REMOVING OR INSTALLING PISTON ASSEMBLY

Fig. 83 Check for Stretched Bolts

1 - STRETCHED BOLT
2 - THREADS ARE NOT STRAIGHT ON LINE
3 - THREADS ARE STRAIGHT ON LINE
4 - UNSTRETCHED BOLT

9 - 52

ENGINE

PISTON & CONNECTING ROD (Continued)

(3) Before installing pistons and connecting rod

assemblies into the bore, ensure that compression
ring gaps are staggered so that neither is in line with
oil ring rail gap (Fig. 84).

(4) Immerse the piston head and rings in clean

engine oil, slide the ring compressor over the piston
and tighten with the special wrench (Fig. 85).
Ensure position of rings does not change dur-
ing this operation.

(5) Install connecting rod bolt protectors on rod

bolts (Fig. 82).

(6) Rotate crankshaft so that the connecting rod

journal is on the center of the cylinder bore. Insert
rod and piston into cylinder bore and guide rod over
the crankshaft journal.

CAUTION: Do Not interchange piston assemblies
cylinder-to-cylinder or bank-to-bank.

(7) The arrow on top of piston must be pointing

toward front of engine (Fig. 86) and oil squirt hole on
connecting rod faces the major thrust (right) side of
the cylinder bore (Fig. 87).

(8) Tap the piston down in cylinder bore, using a

hammer handle. At the same time, guide connecting
rod into position on connecting rod journal.

(9) Install rod caps. Install nuts on cleaned and

oiled rod bolts and tighten nuts to 54 N·m (40 ft. lbs.)
Plus 1/4 turn.

(10) Install the cylinder head(s) (Refer to 9 -

ENGINE/CYLINDER HEAD - INSTALLATION)

(11) Install the oil pan. (Refer to 9 - ENGINE/LU-

BRICATION/OIL PAN - INSTALLATION)

Fig. 84 Piston Ring End Gap Position

1 - SIDE RAIL UPPER
2 - NO. 1 RING GAP
3 - PISTON PIN
4 - SIDE RAIL LOWER
5 - NO. 2 RING GAP AND SPACER EXPANDER GAP

Fig. 85 Piston - Installation

Fig. 86 Piston Orientation

1 - ARROW FACES FRONT OF ENGINE

ENGINE

9 - 53

PISTON & CONNECTING ROD (Continued)

PISTON RINGS

STANDARD PROCEDURE - PISTON RING
FITTING

(1) Wipe cylinder bore clean. Insert ring and push

down with piston to ensure it is square in bore. The
ring gap measurement must be made with the ring
positioning at least 12 mm (0.50 in.) from bottom of
cylinder bore. Check gap with feeler gauge (Fig. 88).
For clearance specifications, (Refer to 9 - ENGINE -
SPECIFICATIONS).

(2) Check piston ring to groove clearance: (Fig. 89).

For clearance specifications, (Refer to 9 - ENGINE -
SPECIFICATIONS).

Fig. 87 Piston and Connecting Rod Positioning (Front View of Engine)

1 - MAJOR THRUST SIDE OF PISTON

2 - OIL SQUIRT HOLE

Fig. 88 Check Gap on Piston Rings

1 - FEELER GAUGE

9 - 54

ENGINE

PISTON & CONNECTING ROD (Continued)

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