Dodge RAM TRUCK 1500 1995 Service Manual page 1708

25-10 EMISSION CONTROL SYSTEMS
CRANKCASE VENTILATION SYSTEM—-8.OL V-10
ENGINE
The 8.0L V-10 engine is equipped with a Crankcase
Ventilation (CCV) system. The CCV system performs
the same function as a conventional PCV system, but
does not use a vacuum controlled valve (PCV valve).
A molded vacuum tube connects manifold vacuum
to the top of the right cylinder head (valve) cover.
The vacuum tube connects to a fixed orifice fitting
(Fig. 14) of a calibrated size 2.6 mm (0.10 inches). It
meters the amount of crankcase vapors drawn out of
the engine. The fixed orifice fitting is grey in
color. A similar fitting (but does not contain a fixed
orifice) is used on the left cylinder head (valve) cover.
This fitting is black in color. Do not interchange
these two fittings.
When the engine is operating, fresh air enters the
engine and mixes with crankcase vapors. Manifold
vacuum draws the vapor/air mixture through the
fixed orifice and into the intake manifold. The vapors
are then consumed during engine combustion.
VACUUM
JBE
AIR INLET
FROM
AIR CLEANER
ORIFICE FITTING
HOSE CONNECTIONS
COIL
PACKS
• J9414-64
Fig. 14 Fixed Orifice Fitting—8.0L V-10 Engine—
Typical
CRANKCASE BREATHER/FILTER
3.9L/5.2L/5.9L GAS POWERED ENGINES
The crankcase breather/filter (Fig. 15) is used on
gas powered engines only (except 8.0L V-10). It is lo­
cated on the cylinder head (valve) cover. It must be
kept clean and lubricated. At the recommended inter­
val, remove the filter and wash it thoroughly in ker­
osene or similar solvent. Lubricate or wet the filter
by inverting it and filling with SAE 30 engine oil.
Filter must then be thoroughly drained. More fre­
quent service may be necessary for vehicles operated
extensively on short run, stop and go or extended en­
gine idle service.
The filter must be replaced at correct intervals. Re­
fer to Lubrication and Maintenance, Group 0 in this
service manual.
CYLINDER HEAD
COVER
MOUNTING NIPPLE
8925-28
Fig. 15 Crankcase Breather/Filter—Gas Powered
Engines (Except S.OL V-10)
EGR (EXHAUST GAS RECIRCULATION) SYSTEMS
GENERAL INFORMATION
The EGR system reduces oxides of nitrogen (NOx)
in the engine exhaust and helps prevent spark
knock. This is accomplished by allowing a predeter­
mined amount of hot exhaust gas to recirculate and
dilute the incoming fuel/air mixture. This dilution re­
duces peak flame temperature during combustion.
A malfunctioning EGR system can cause engine
spark knock, sags or hesitation, rough idle, engine
stalling and poor driveability.
The EGR system is not used with the diesel engine.
EGR SYSTEM OPERATION
The system consists of:
• An EGR valve assembly (Figs. 16, 17 or 18)
mounted to the intake manifold.
• An EGR valve control containing a combination
back-pressure transducer and an electric vacuum so­
lenoid (Figs. 16, 17 or 18).
• The powertrain control module (PCM) to control
the electric solenoid portion of the valve control.
• An EGR tube (Figs. 19 or 20) connecting a passage
in the intake manifold (near the EGR valve) to the
rear of the right exhaust manifold.
• Hoses to connect the various components.
When the PCM removes the ground signal to the
electric solenoid portion of the valve control, EGR
system operation starts to occur. The PCM will mon­
itor and determine when to supply and remove this
ground signal depending on certain engine tempera­
tures, throttle positions and other engine operating
conditions.
If the electrical connector to the EGR valve
control is disconnected, or the electrical signal
is lost, the EGR valve will operate at all times.