Positive Crankcase Ventilation System; Vacuum Dump Valve Replacement - Jeep J-10 Series 1982 Technical & Service Manual

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(1) Start engine and warm to normal operating
temperature.
(2) Remove vacuum dump valve vacuum hose from
connection at intake manifold and plug/cap manifold
connection.
(3) Accelerate engine to 2000 rpm. Vacuum should
be present at exhaust ports on bottom of valve. If not,
replace valve.
(4) Connect vacuum dump valve vacuum hose to
manifold. With engine speed at 2000 rpm, no vacuum
should be present at exhaust ports on bottom of valve. If
present, replace valve.
Vacuum Dump Valve Replacement
Removal
(1) Remove vacuum hoses from vacuum dump
valve.
(2) Remove valve.
Installation
(1) Connect manifold vacuum hose to port "A" (fig.
1J-144).
(2) Connect EGR valve vacuum hose to port "B"
(fig. 1J-144).
EGR DELAY VALVES
Forward Delay Valve
A forward delay valve is located between the EGR
CTO valve and the EGR valve for certain engine appli
cations (refer to Vacuum Diagrams for exact location).
Its purpose is to modify the initial vacuum applied to the
EGR valve by delaying the full effects of the vacuum.
With gradual vacuum applied to the EGR valve, a harsh,
sudden activation of the EGR system is avoided.
FUEL SYSTEMS U-77
The black side of the valve is installed toward the
EGR vacuum source.
Reverse Delay Valve
A reverse delay valve is located between the EGR CTO
valve and the manifold vacuum source for certain engine
applications (refer to Vacuum Diagrams for exact loca
tion). The purpose of the valve is to retain the manifold
vacuum applied to the distributor vacuum advance
mechanisim when the engine is cold and is rapidly accel
erated. This prevents retardation of the ignition timing.
When the engine coolant temperature is heated to the
calibrated temperature switching point, the CTO valve
switches to ported vacuum.
A
'A" TO MANIFOLD
3
titi
\
*B" TO EGR VALVE
90568
Rg. U-144 EGR Vacuum Dump Valvo
POSITIVE CRANKCASE
VENTILATION (PCV)
SYSTEM
Page
Components 1J-78
General U-77
Operation—PCV System 1J-78
GENERAL
The PCV system functions to prevent crankcase vapor
from entering the atmosphere. Filtered air is routed into
the crankcase and vapor forced into the intake manifold
PCV Valve Air Inlet Filter Maintenance
PCV Valve Functional Test
Page
1J-79
1J-78
and burned during the engine combustion process.
In addition to controlling crankcase vapor, the system
also constantly ventilates the crankcase, which helps to
prevent the formation of sludge.