Dodge Durango (DN). Manual — part 439

ENGINE LUBRICATION SYSTEM

DESCRIPTION

A gear-type positive displacement pump (Fig. 3) is

mounted at the underside of the rear main bearing
cap. The pump uses a pick-up tube and screen
assembly to gather engine oil from the oil pan.

OPERATION

The pump draws oil through the screen and inlet

tube from the sump at the rear of the oil pan. The oil
is driven between the drive and idler gears and
pump body, then forced through the outlet to the
block. An oil gallery in the block channels the oil to
the inlet side of the full flow oil filter. After passing
through the filter element, the oil passes from the
center outlet of the filter through an oil gallery that
channels the oil up to the main gallery, which
extends the entire length on the right side of the
block. The oil then goes down to the No. 1 main bear-

ing, back up to the left side of the block, and into the
oil gallery on the left side of the engine.

Galleries extend downward from the main oil gal-

lery to the upper shell of each main bearing. The
crankshaft is drilled internally to pass oil from the
main bearing journals to the connecting rod journals.
Each connecting rod bearing has half a hole in it, oil
passes through the hole when the rods rotate and the
hole lines up, oil is then thrown off as the rod
rotates. This oil throwoff lubricates the camshaft
lobes, distributor drive gear, cylinder walls, and pis-
ton pins.

The hydraulic valve tappets receive oil directly

from the main oil gallery. The camshaft bearings
receive oil from the main bearing galleries. The front
camshaft bearing journal passes oil through the cam-
shaft sprocket to the timing chain. Oil drains back to
the oil pan under the No. 1 main bearing cap.

The oil supply for the rocker arms and bridged

pivot assemblies is provided by the hydraulic valve
tappets, which pass oil through hollow push rods to a
hole in the corresponding rocker arm. Oil from the
rocker arm lubricates the valve train components.
The oil then passes down through the push rod guide
holes and the oil drain-back passages in the cylinder
head, past the valve tappet area, and then returns to
the oil pan.

Fig. 1 Firing Order

Fig. 2 Engine Identification Number

Fig. 3 Positive Displacement Oil Pump—Typical

1 – INNER ROTOR AND SHAFT
2 – BODY
3 – DISTRIBUTOR DRIVESHAFT (REFERENCE)
4 – COTTER PIN
5 – RETAINER CAP
6 – SPRING
7 – RELIEF VALVE
8 – LARGE CHAMFERED EDGE
9 – BOLT
10 – COVER
11 – OUTER ROTOR

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DESCRIPTION AND OPERATION (Continued)

Fig.

4

Oil

Lubrication

System

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DESCRIPTION AND OPERATION (Continued)

EXHAUST MANIFOLD

DESCRIPTION

The exhaust manifolds are constructed of cast iron

and are LOG type with balanced flow (Fig. 5). One
exhaust manifold is attached to each cylinder head.

OPERATION

The exhaust manifolds collect the engine exhaust

exiting the combustion chambers, then channels the
exhaust gases to the exhaust pipes attached to the
manifolds.

INTAKE MANIFOLD

DESCRIPTION

The aluminum intake manifold (Fig. 6) is a single

plane design with equal length runners and uses a
separate plenum, therefore the manifold does have a
plenum gasket. It also uses separate flange gaskets
and front and rear cross-over gaskets. Extreme care

must be used when sealing the gaskets to ensure
that excess sealant does not enter the intake runners
causing a restriction. Whenever the intake manifold
is removed inspect the plenum pan for evidence of
excess oil buildup, this condition indicates that the
plenum pan gasket is leaking.

OPERATION

The intake manifold, meters and delivers air to the

combustion chambers allowing the fuel delivered by
the fuel injectors to ignite, thus producing power.

1 – OIL DEFLECTOR TAB
2 – BOLT
3 – ROCKER ARM PIVOT
4 – ROCKER ARM
5 – DRIP OILING FOR VALVE TIP
6 – CYLINDER HEAD BOSS
7 – TO MAIN BEARINGS
8 – TO CAMSHAFT BEARINGS
9 – ROCKER ARM
10 – HOLLOW PUSH ROD
11 – TAPPET
12 – TO CONNECTING ROD BEARINGS
13 – OIL INTAKE

14 – OIL PUMP
15 – OIL FILTER
16 – CRANKSHAFT
17 – FROM OIL PUMP
18 – OIL TO FILTER
19 – OIL FROM FILTER TO SYSTEM
20 – PASSAGE TO CAMSHAFT REAR BEARING
21 – RIGHT OIL GALLERY
22 – PLUG
23 – OIL PASSAGE FOR OIL PRESSURE INDICATOR LIGHT
24 – OIL SUPPLY VIA HOLLOW PUSH ROD SUPPLY IS FROM

OIL GALLERY METERED THROUGH HYDRAULIC TAPPET

25 – OIL SUPPLY FROM HOLLOW PUSH ROD

Fig. 5 Exhaust Manifolds—V-8 Gas Engines Typical

1 – EXHAUST MANIFOLD (LEFT)
2 – BOLTS & WASHERS
3 – NUTS & WASHERS
4 – EXHAUST MANIFOLD (RIGHT)
5 – BOLTS & WASHERS

Fig. 6 Intake Manifold and Throttle Body—V-8 Gas

Engines Typical

1 – FUEL RAIL ASSEMBLY
2 – FUEL RAIL MOUNTING BOLTS
3 – FUEL RAIL CONNECTING HOSES

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DESCRIPTION AND OPERATION (Continued)

CYLINDER HEAD COVER GASKET

DESCRIPTION

The cylinder head cover gasket is a steel-backed

silicone gasket, designed for long life usage (Fig. 7).

OPERATION

The steel-backed silicone gasket is designed to seal

the cylinder head cover for long periods of time
through extensive heat and cold, without failure. The
gasket is designed to be reusable.

CYLINDER HEAD

DESCRIPTION

The cast iron cylinder heads are mounted to the

cylinder block using ten bolts (Fig. 8). The spark
plugs are located in the peak of the wedge between
the valves.

OPERATION

The cylinder head closes the combustion chamber

allowing the pistons to compress the air fuel mixture
to the correct ratio for ignition. The valves located in
the cylinder head open and close to either allow clean
air into the combustion chamber or to allow the
exhaust gases out, depending on the stroke of the
engine.

VALVES AND VALVE SPRINGS

DESCRIPTION

Both the intake and exhaust valves are made of

steel. The intake valve is 48.768 mm (1.92 inches) in
diameter and the exhaust valve is 41.148 mm (1.62
inches) in diameter and has a 2.032 mm (0.080 inch)
wafer interia welded to the tip for durability. These
valves are not splayed.

ENGINE OIL PAN

DESCRIPTION

The stamped steel engine oil pan is located at the

bottom of the engine, and contains a drain plug for
draining the engine oil.

OPERATION

The oil pan holds the engine oil and seals and pro-

tects the engine lower components from contami-
nates.

CRANKSHAFT OIL SEALS

DESCRIPTION

The crankshaft rear seal is a two piece viton seal.

The crankshaft front seal is a one piece viton seal
with a steel housing. The front seal is located in the
engine front cover. One part of the two piece rear
seal is located in a slot in the number five (5) crank-
shaft main bore, the second part of the two piece seal
is located in the number five (5) main bearing cap.

OPERATION

The crankshaft seals prevent oil from leaking from

around the crankshaft, either from the rear of the
engine or from the engine front cover.

PISTON AND 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.

Fig. 7 Cylinder Head Cover Gasket V-8 Gas Engines

1 – CYLINDER HEAD COVER GASKET

Fig. 8 Cylinder Head Assembly—V-8 Gas Engines

1 – EXHAUST VALVE
2 – SPARK PLUGS
3 – EXHAUST VALVES
4 – SPARK PLUGS
5 – EXHAUST VALVE
6 – INTAKE VALVES
7 – INTAKE VALVES

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DESCRIPTION AND OPERATION (Continued)