NOTE: The evaporative system uses specially man-
ufactured lines/hoses. If replacement becomes nec-
essary, only use fuel resistant, low permeation
hose.
Certain components can be found in (Fig. 1).
DESCRIPTION - CCV SYSTEM
The 4.0L 6±cylinder engine is equipped with a
Crankcase Ventilation (CCV) system. The system
consists of:
²A fixed orifice fitting of a calibrated size. This
fitting is pressed into a rubber grommet located on
the top/rear of cylinder head (valve) cover (Fig. 2).
²a pair of breather tubes (lines) to connect the
system components.
²the air cleaner housing.
²an air inlet fitting (Fig. 2).
DESCRIPTION - PCV SYSTEM
The 4.7L V-8 engine is equipped with a closed
crankcase ventilation system and a Positive Crank-
case Ventilation (PCV) valve.
This system consists of:
Fig. 1 ORVR / LDP COMPONENTS
1 - FUEL TANK (LEFT SIDE) 6 - EVAP CANISTER
2 - FRAME RAIL (LEFT-REAR OUTSIDE) 7 - LDP FILTER
3 - FUEL VENT TUBE 8 - TWO-PIECE SUPPORT BRACKET
4 - FUEL FILL TUBE 9 - LEAK DETECTION PUMP (LDP)
5 - CONTROL VALVE
Fig. 2 CCV SystemÐ4.0L Engine
1 - AIR INLET FITTING
2 - FIXED ORIFICE FITTING
3 - CCV BREATHER TUBE (REAR)
4 - INT. MAN. FITTING
5 - CCV BREATHER TUBE (FRONT)
WJEVAPORATIVE EMISSIONS 25 - 25
EVAPORATIVE EMISSIONS (Continued)
²a PCV valve mounted to the oil filler housing
(Fig. 3). The PCV valve is sealed to the oil filler
housing with an o-ring.
²the air cleaner housing
²two interconnected breathers threaded into the
rear of each cylinder head (Fig. 4).
²tubes and hose to connect the system compo-
nents.
OPERATION
OPERATION - 4.0L CCV SYSTEM
The CCV system performs the same function as a
conventional PCV system, but does not use a vacuum
controlled PCV valve.
The fixed orifice fitting meters the amount of
crankcase vapors drawn out of the engine.
When the engine is operating, fresh air enters the
engine and mixes with crankcase vapors. Engine vac-uum draws the vapor/air mixture through the fixed
orifice and into the intake manifold. The vapors are
then consumed during engine combustion.
OPERATION - 4.7L PCV SYSTEM
The PCV system operates by engine intake mani-
fold vacuum. Filtered air is routed into the crankcase
through the air cleaner hose and crankcase breath-
ers. The metered air, along with crankcase vapors,
are drawn through the PCV valve and into a passage
in the intake manifold. The PCV system manages
crankcase pressure and meters blow-by gases to the
intake system, reducing engine sludge formation.
The PCV valve contains a spring loaded plunger.
This plunger meters the amount of crankcase vapors
routed into the combustion chamber based on intake
manifold vacuum.
TYPICALPCV valves are shown in (Fig. 5), (Fig.
6) and (Fig. 7).
When the engine is not operating, or during an
engine pop-back, the spring forces the plunger back
against the seat (Fig. 5). This will prevent vapors
from flowing through the valve.
Fig. 3 PCV Valve/Oil Filler Tube (Housing)Ð4.7L
Engine
1 - O-RING
2 - LOCATING TABS
3 - CAM LOCK
4 - OIL FILLER TUBE
5 - PCV LINE/HOSE
6 - P C V VA LV E
Fig. 4 PCV System Hoses/TubesÐ4.7L Engine
1 - FRESH AIR FITTING
2 - CONNECTING TUBES/HOSES
3 - CRANKCASE BREATHERS (2)
4 - RUBBER HOSE
5 - AIR CLEANER RESONATOR
25 - 26 EVAPORATIVE EMISSIONSWJ
EVAPORATIVE EMISSIONS (Continued)
