Exhaust Systems; Exhaust Manifolds, Mufflers And Pipes; Restricted Exhaust System Diagnosis - Jeep 1979 CJ-5 Technical & Service Manual

1K-1
P a p Page
Ah- Guard Systaa 1K-9
Exhaust Manifolds, i u f f l i r s , mi Pipes
1K-1
Catalytic CMvartar SystM 1K-13 Tools liC-15
wmmmmm ssm
P I P E S
F i l l P i p
Exhaust Manifold 1K-6
Pipes m - 9
Geiarai 1K-1 Restricted Exhaust System Diagnosis 1K-1
Heat Valve 1K-7 Specifications 1K-9
Muffler 1K-8
GENERAL
The basic exhaust system on all vehicles consists of
exhaust manifold(s), front exhaust pipe, catalytic con-
verter, muffler and tailpipe.
All six-cylinder CJ models use a catalytic converter
(fig. 1K-1). Six-cylinder CJ models for California use a
monolithic catalytic converter and a pellet-type catalytic
converter (fig. 1K-1). All eight-cylinder CJ models use a
single pellet-type catalytic converter (fig. 1K-2).
Cherokee, Wagoneer and Truck models use a single
pellet-type catalytic converter (fig. 1K-3 through 1K-6).
The exhaust system must be properly aligned to pre-
vent stress, leakage, and grounding. If the system
grounds on any body panel, it may amplify objectionable
noises originating from the engine or the body. When
inspecting an exhaust system, check for cracked or loose
joints, stripped screw threads, and corrosion damage.
Check for worn or broken hangers. Eeplace all parts that
are badly corroded or damaged. Do not attempt to
repair.
RESTRICTED EXHAUST SYSTEM DIAGNOSIS
] A restricted or blocked exhaust system usually results
. in loss of power or popping through the carburetor.
Verify that the condition is not caused by ignition or
timing problems, then perform a visual inspection of the
exhaust system. If the restriction cannot be located by
visual inspection, perform the following procedure.
(1) Attach a vacuum gauge to' intake manifold.
(2) Connect tachometer.
(3) Start engine and observe vacuum gauge. Gauge
should indicate 16 to 21 inches of vacuum.
(4) Increase engine speed to 2,000 rpm and observe
vacuum gauge. Vacuum will drop when speed is in-
creased rapidly, but should settle at 16 to 21 inches and
remain steady. If vacuum drops below 16 inches, ex-
haust system is restricted or blocked. Stop engine and
proceed to step (5).
(5) Disconnect exhaust pipe at manifold.
(6) Start engine and increase speed to 2,000 rpm.
Observe vacuum gauge.
(a) If vacuum settles at 16 to 21 inches, restric-
tion or blockage is in exhaust pipe, catalytic converter or
muffler.
(b) If vacuum drops below 16 inches with ex-
haust pipe disconnected, exhaust manifold is restricted.
(7) Connect exhaust pipe, remove muffler and check
vacuum gauge.
(a) If vacuum drops below 16 inches, restriction
or blockage is in catalytic converter.
(b) If vacuum is normal, muffler is restricted.