Dodge Durango (DN). Manual — part 418

firing order is 1–8–4–3–6–5–7–2. The engine serial
number is located at the right front side of the
engine block (Fig. 1)

ENGINE LUBRICATION SYSTEM

DESCRIPTION

The lubrication system (Fig. 2) is a full flow filtra-

tion pressure feed type.

OPERATION

Oil from the oil pan is pumped by a gerotor type oil

pump directly mounted to the crankshaft nose. Oil
pressure is controlled by a relief valve mounted
inside the oil pump housing. For lubrication flow
refer to (Fig. 2).

The camshaft exhaust valve lobes and rocker arms

are lubricated through a small hole in the rocker
arm; oil flows through the lash adjuster then through
the rocker arm and onto the camshaft lobe. Due to
the orentation of the rocker arm, the camshaft intake
lobes are not lubed in the same manner as the
exhaust lobes. The intake lobes are lubed through
internal passages in the camshaft. Oil flows through
a bore in the number 3 camshaft bearing bore, and
as the camshaft turns, a hole in the camshaft aligns
with the hole in the camshaft bore allowing engine
oil to enter the camshaft tube. The oil then exits
through 1.6mm (0.063 in.) holes drilled into the

intake lobes, lubricating the lobes and the rocker
arms.

ENGINE LUBRICATION FLOW CHART—BLOCK: TABLE 1

FROM

TO

Oil Pickup Tube

Oil Pump

Oil Pump

Oil Filter

Oil Filter

Block Main Oil Gallery

Block Main Oil Gallery

1. Crankshaft Main Journal

2. Left Cylinder Head*

3. Right Cylinder Head*

Crankshaft Main Journals

Crankshaft Rod Journals

Crankshaft Number One Main Journal

1.Front Timing Chain Idler Shaft

2. Both Secondary Chain Tensioners

Left Cylinder Head

See Table 2

Right Cylinder Head

See Table 2

* The cylinder head

gaskets have an oil restricter to control oil flow to the cylinder heads.

Fig. 1 Engine Identification Location.

1 – VEHICLE VIN NUMBER LOCATION
2 – CYLINDER BLOCK RIGHT HAND SIDE
3 – CYLINDER BORE #2

DN

4.7L ENGINE

9 - 3

DESCRIPTION AND OPERATION (Continued)

1 – LEFT CYLINDER HEAD OIL GALLERY
2 – OIL PRESSURE SENSOR LOCATION
3 – TO LEFT CYLINDER HEAD
4 – OIL FEED TO IDLER SHAFT
5 – OIL PUMP OUTLET TO BLOCK
6 – OIL PUMP

7 – TO CRANKSHAFT MAIN JOURNALS
8 – RIGHT CYLINDER HEAD OIL GALLERY
9 – TO RIGHT CYLINDER HEAD
10 – CYLINDER BLOCK MAIN GALLERY
11 – OIL FEED TO BOTH SECONDARY TENSIONERS

Fig. 2 Engine Oil Lubrication System

9 - 4

4.7L ENGINE

DN

DESCRIPTION AND OPERATION (Continued)

ENGINE LUBRICATION FLOW CHART—CYLINDER HEADS: TABLE 2

FROM

TO

Cylinder Head Oil Port (in bolt hole)

Diagonal Cross Drilling to Main Oil Gallery

Main Oil Gallery (drilled through head from rear to front)

1. Base of Camshaft Towers

2. Lash Adjuster Towers

Base of Camshaft Towers

Vertical Drilling Through Tower to Camshaft Bearings**

Lash Adjuster Towers

Diagonal Drillings to Hydraulic Lash Adjuster Pockets

** 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

and

improved

NVH

an

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.

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
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.

DN

4.7L ENGINE

9 - 5

DESCRIPTION AND OPERATION (Continued)

2000 DN Service Manual
Publication No. 81-370-0016
TSB 26-12-99

December, 1999

VALVE SPRING

DESCRIPTION

The valve springs are made from high strength

chrome silicon steel. The springs are common for
intake and exhaust applications. The valve spring
seat is integral with the valve stem seal, which is a
positive type seal to control lubrication.

HYDRAULIC LASH ADJUSTER

DESCRIPTION

Valve lash is controlled by hydraulic lash adjusters

that are stationary mounted in the cylinder heads.
The lash adjusters have a hole in the ball plunger
that feeds oil through the rocker arm squirt holes for
rocker arm roller and camshaft lobe lubrication.

TIMING DRIVE SYSTEM

DESCRIPTION

The timing drive system has been designed to pro-

vide quiet performance and reliability to support a
non-free wheeling engine. Specifically the intake
valves are non-free wheeling and can be easily dam-
aged with forceful engine rotation if camshaft-to-
crankshaft timing is incorrect. The timing drive
system consists of a primary chain and two second-
ary timing chain drives.

OPERATION

The primary timing chain is a single inverted tooth

type. The primary chain drives the large fifty tooth
idler sprocket directly from a 25 tooth crankshaft
sprocket. Primary chain motion is controlled by a
pivoting leaf spring tensioner arm and a fixed guide.
The arm and the guide both use nylon plastic wear
faces for low friction and long wear. The primary
chain receives oil splash lubrication from the second-
ary chain drive and oil pump leakage. The idler
sprocket assembly connects the primary and second-
ary chain drives. The idler sprocket assembly con-
sists of two integral thirty tooth sprockets and a fifty
tooth sprocket that is splined to the assembly. The
spline joint is a non – serviceable press fit anti rattle
type. A spiral ring is installed on the outboard side of
the fifty tooth sprocket to prevent spline disengage-
ment. The idler sprocket assembly spins on a station-
ary idler shaft. The idler shaft is press-fit into the
cylinder block. A large washer on the idler shaft bolt
and the rear flange of the idler shaft are used to con-
trol sprocket thrust movement. Pressurized oil is
routed through the center of the idler shaft to pro-
vide lubrication for the two bushings used in the
idler sprocket assembly.

There are two secondary drive chains, both are

inverted tooth type, one to drive the camshaft in each
SOHC cylinder head. There are no shaft speed
changes in the secondary chain drive system. Each
secondary chain drives a thirty tooth cam sprocket
directly from the thirty tooth sprocket on the idler
sprocket assembly. A fixed chain guide and a hydrau-
lic oil damped tensioner are used to maintain tension
in each secondary chain system. The hydraulic ten-
sioners for the secondary chain systems are fed pres-
surized oil from oil reservoir pockets in the block.
Each tensioner also has a mechanical ratchet system
that limits chain slack if the tensioner piston bleeds
down after engine shut down. The tensioner arms
and guides also utilize nylon wear faces for low fric-
tion and long wear. The secondary timing chains
receive lubrication from a small orifice in the ten-
sioners. This orifice is protected from clogging by a
fine mesh screen which is located on the back of the
hydraulic tensioners.

CAMSHAFT

DESCRIPTION

The camshafts consist of powdered metal steel

lobes which are sinter-bonded to a steel tube. A steel
post or nose piece is friction-welded to the steel cam-
shaft tube. Five bearing journals are machined into
the camshaft, four on the steel tube and one on the
steel nose piece. Camshaft end play is controlled by
two thrust walls that border the nose piece journal.
Engine oil enters the hollow camshafts at the third
journal and lubricates every intake lobe rocker
through a drilled passage in the intake lobe.

ROCKER ARM

DESCRIPTION

The rocker arms are steel stampings with an inte-

gral roller bearing. The rocker arms incorporate a 2.8
mm (0.11 inch) oil hole in the lash adjuster socket for
roller and camshaft lubrication.

CYLINDER HEAD COVER

DESCRIPTION

The cylinder head covers are made of die cast mag-

nesium, and are not interchangeable from side-to-
side. It is imperative that nothing rest on the
cylinder head covers. Prolonged contact with other
items may wear a hole in the cylinder head cover.

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4.7L ENGINE

DN

DESCRIPTION AND OPERATION (Continued)