Dodge 2000 DURANGO Service Manual page 514

DN
DESCRIPTION AND OPERATION (Continued)
ENGINE LUBRICATION FLOW CHART—CYLINDER HEADS: TABLE 2
Cylinder Head Oil Port (in bolt hole)
Main Oil Gallery (drilled through head from rear to front)
Base of Camshaft Towers
Lash Adjuster Towers
** The number three camshaft bearing journal feeds oil into the hollow camshaft tubes. Oil is routed to the intake
lobes, which have oil passages drilled into them to lubricate the rocker arms.
CYLINDER BLOCK
DESCRIPTION
The cylinder block is made of cast iron. The block
is a closed deck design with the left bank forward. To
provide high rigidity
enhanced compacted graphite bedplate is bolted to
the block. The block design allows coolant flow
between the cylinders bores, and an internal coolant
bypass to a single poppet inlet thermostat is included
in the cast aluminum front cover.
CRANKSHAFT
DESCRIPTION
The crankshaft is constructed of nodular cast iron.
The crankshaft is a crosshaped four throw design
with eight counterweights for balancing purposes.
The crankshaft is supported by five select main bear-
ings with the number three serving as the thrust
washer location. The main journals of the crankshaft
are cross drilled to improve rod bearing lubrication.
The number eight counterweight has provisions for
crankshaft position sensor target wheel mounting.
The select fit main bearing markings are located on
the rear side of the target wheel. The crankshaft oil
seals are one piece design. The front oil seal is
retained in the timing chain cover, and the rear seal
is pressed in to a bore formed by the cylinder block
and the bedplate assembly.
PISTON AND CONNECTING ROD
DESCRIPTION
CAUTION: Do not use a metal stamp to mark con-
necting rods as damage may result, instead use ink
or a scratch awl.
EARLY BUILD
The pistons are made of a high strength aluminum
alloy with an anodized top ring groove and crown. Piston
skirts are coated with a solid lubricant (Molykote) to
reduce friction and provide scuff resistance. The connect-
ing rods are made of forged powdered metal, with a
"fractured cap" design. A pressed fit piston pin is used to
attach the piston and connecting rod.
FROM
and improved NVH
Diagonal Cross Drilling to Main Oil Gallery
1. Base of Camshaft Towers
2. Lash Adjuster Towers
Vertical Drilling Through Tower to Camshaft Bearings**
Diagonal Drillings to Hydraulic Lash Adjuster Pockets
LATE BUILD
The pistons are made of high strength aluminum
alloy. The top ring groove and crown are Not anod-
ized, instead the top ring is coated with an anti-scuff
coating to reduce friction on the top ring. The piston
an
skirts are coated with a solid lubricant (Molykote) to
reduce friction and provide scuff resistance. The con-
necting rods are made of forged powdered metal,
with a "fractured cap" design. A pressed fit piston pin
is used to attach the piston and connecting rod.
CYLINDER HEAD
DESCRIPTION
The cylinder heads are made of an aluminum alloy.
The cylinder head features two valves per cylinder
with pressed in powdered metal valve guides. The
cylinder heads also provide enclosures for the timing
chain drain, necessitating unique left and right cylin-
der heads.
VALVE GUIDES
DESCRIPTION
The valve guides are made of powered metal and
are pressed into the cylinder head. The guides are
not replaceable or serviceable, and valve guide ream-
ing is not recommended. If the guides are worn
beyond acceptable limits, replace the cylinder heads.
VALVES
DESCRIPTION
The valves are made of heat resistant steel and
have chrome plated stems to prevent scuffing. Each
valve is actuated by a roller rocker arm which pivots
on a stationary lash adjuster. All valves use three
bead lock keepers to retain the springs and promote
valve rotation.
VALVE STEM SEAL
DESCRIPTION
The valve stem seals are made of rubber and incor-
porate an integral steel valve spring seat. The inte-
gral garter spring maintains consistent lubrication
control to the valve stems.
4.7L ENGINE
2000 DN Service Manual
Publication No. 81-370-0016
TSB 26-12-99 December, 1999
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