GMC 1982 Light Duty Truck, Service Manual

Page: 960 / 1435

6 E -1 6 ENGINE EMISSION CONTROLS
E N G IN E L E V E R
B R A C K E T
R E T A IN E R
A C T U A T O R
Fig. 6E-25--EFE System-4.1 L
• Move exhaust heat valve by hand. If binding or stuck,
free with manifold heat valve lubricant, GM Part No.
1050422 or equivalent. If valve cannot be freed, replace
valve.
Checking EFE System
1. With engine cold, position transmission in neutral or
park and apply parking brake.
2. Start engine and observe movement of actuator rod and
exhaust heat valve. Valve should move to its closed
position.
3. If valve does not close, disconnect hose at actuator and
check for vacuum.
• If there is vacuum, replace actuator.
• If there is no vacuum, disconnect hose at TVS-to-
vacuum source.
• If there is vacuum at hose, replace TVS.
• If there is no vacuum, check for deteriorated hose
and vacuum source to determine lack of vacuum.
4. When coolant reaches 180°F (82°C) (V8), or oil
reaches 150°F (66°C) (six cylinder), the exhaust heat
valve should move to its open position.
5. If valve does not move, disconnect hose at actuator and
check for vacuum.
• If there is vacuum, replace TVS.
• If there is no vacuum, replace actuator.
C oolant T e m p eratu re T h erm al V acu u m Sw itch
(TVS) - V 8
Replacement
1. Drain coolant below level of engine coolant outlet
housing.
2. Disconnect hoses at TVS ports.
3. Remove TVS.
4. Apply a soft setting sealant uniformly on replacement
TVS male threads. No sealant should be applied to
sensor end of TVS.
5. Install TVS, tighten to 14Nm (120 pound inches) and
then hand torque clockwise as required to align TVS to
accomodate hoses.
6. Connect hoses to TVS ports.
7. Add coolant as required.
O il T em p eratu re Therm al V a c u u m Sw itch (TVS) -
L6
Replacement
1. Disconnect hoses at TVS ports.
2. Remove TVS switch.
3. Install TVS switch.
4. Connect hoses to TVS ports.
A ctu ator Assem bly (Fig. 6 E -2 5 thru 29)
The actuator assembly is located on a bracket attached
to right exhaust manifold or mounted directly to the right or
left exhaust manifold. Actuators which are remotely located
on bracket are connected to the heat valve by a rod.
Replacement
1. Disconnect vacuum hose from actuator.
2. Remove fasteners holding actuator to mainifold or
bracket.
3. If used, disconnect rod from actuator and remove.
4. Remove actuator.
E X H A U S T M A N IF O L D
E N G IN E
E M IS S IO N HO SE A S M
10 1631
Fig. 6 E -2 6 -A c tu a to r and R od-5.7L-G / CK
Fig. 6E-27--Exhaust Heat Valve-5.OL-CK