Thermal Vacuum Switch (Tvs); Tvs Replacement; Egr Vacuum Dump Valve; Vacuum Dump Valve Functional Test - Jeep J-10 Series 1982 Technical & Service Manual

1J-76 FUEL SYSTEMS
Removal—Six-Cylinder Engine
WARNING: Serious burns can result ifpressure is not
released and if hot coolant is not drained before remov
ing valve from block.
(1) Drain Coolant from radiator.
(2) Disconnect vacuum hoses.
(3) Use open-end wrench to remove valve from in
take manifold.
Installation—Six-Cylinder Engine
(1) Install EGR CTO valve on intake manifold.
(2) Connect vacuum hoses.
(3) Install coolant and purge air from cooling
system.
Removal—Eight-Cylinder Engine
WARNING: Serious burns can result ifpressure is not
released and if hot coolant is not drained before remov
ing valve from intake manifold.
(1) Drain coolant from radiator.
(2) Remove air cleaner assembly.
(3) If necessary, remove ignition coil bracket at
taching screw and tip coil away from EGR CTO valve.
(4) Disconnect vacuum hoses from CTO valve.
(5) Using open-end wrench, remove valve from in
take manifold or engine, as applicable.
Installation—Eight-Cylinder Engine
(1) Install EGR CTO valve in intake manifold or
engine, as applicable.
(2) If removed, install ignition coil and bracket with
attaching screw.
(3) Connect vacuum hoses to valve.
(4) Install air cleaner assembly.
(5) Install coolantand purgecooling system of air.
THERMAL VACUUM SWITCH (TVS)
The Thermal Vacuum Switch (TVS) is located in the
air cleaner and functions as an On-Off switch controlled
by air cleaner air temperature (fig. 1J-143). The TVS
controls the vacuum passage between the EGR CTO
Valve and the EGR Valve. At air temperatures below
40° to 50°F (4.4° to 10°C), the TVS limits the vacuum
applied to the EGR valve and, by doing so, prevents
EGR operation. This improves cold engine driveability.
NOTE: A TVS is also used with other systems whose
operation is dependent on air cleaner air temperature.
TVS Functional Test
(1) Cool air cleaner air below TVS operational tem
perature limits: 40° to 50°F (4.4° to 10°C).
TO EGR CTO VALVE
TO EGR VALVE
90567
Rg. 1J-143 Thermal Vacuum Switch (TVS)
(2) Disconnect vacuum hoses from TVS and connect
external vacuum source to one nipple and vacuum gauge
to other nipple (fig. 1J-143).
(3) Apply vacuum to TVS. Vacuum should not be
indicated on gauge through TVS when air temperature
is below 40° to 50°F (4.4° to 10°C). If vacuum is in
dicated through TVS, replace it.
(4) Start engine and warm air cleaner air above
50°F (10°C). Vacuum should be indicated on gauge
through TVS when air temperature exceeds 50°F (10°C).
If vacuum is not indicated on gauge through TVS, re
place it.
TVS Replacement
Removal
(1) Remove air cleaner.
(2) Remove filter element.
(3) Remove retaining clip(s) attaching TVS to air
cleaner.
(4) Remove vacuum hoses.
Installation
(1) Position TVS in air cleaner.
(2) Install retaining clip(s).
(3) Install vacuum hoses.
(4) Install filter element.
(5) Install air cleaner.
EGR VACUUM DUMP VALVE
The EGR Vacuum Dump Valve is connected in paral
lel with the EGR vacuum source and the EGR valve for
eight-cylinder engines. It functions to stop EGR oper
ation when intake manifold vacuum drops to a level of 3
to 5 in. Hg (10 to 17 kPa), thereby effectively "dumping"
the vacuum controlling EGR operation.
Vacuum Dump Valve Functional Test
WARNING: Use extreme caution when engine is oper
ating. Do not stand-in direct line with fan. Do not put
hands near pulleys, belts or fan. Do not wear loose
clothing