Jeep Cherokee 1999 Electronic Service Manual page 1167

11 - 2 EXHAUST SYSTEM
DI AGN OSI S AN D T EST I N G
EXHAUST SYSTEM
CONDITION
EXCESSIVE EXHAUST NOISE OR
LEAKING EXHAUST GASES
When servicing and replacing exhaust system components, disconnect the oxygen sensor connector(s). Allowing
the exhaust to hang by the oxygen sensor wires will damage the harness and/or sensor.
REM OVAL AN D I N STALLAT I ON
EXHAUST PIPE
WARNING: IF TORCHES ARE USED WHEN WORK-
ING ON THE EXHAUST SYSTEM, DO NOT ALLOW
THE FLAME NEAR THE FUEL LINES.
CAUTION: When servicing exhaust system compo-
nents, disconnect the oxygen sensor connector.
Allowing the exhaust system to hang by the oxygen
sensor harness will damage the wiring and/or sen-
sor.
REMOVAL
(1) Ra ise a n d su ppor t t h e veh icle.
(2) Sa t u r a t e t h e bolt s a n d n u t s wit h h ea t va lve
lu br ica n t (F ig. 2). Allow 5 m in u t es for pen et r a t ion .
(3) Discon n ect t h e oxygen sen sor con n ect or (F ig.
3).
(4) Discon n ect t h e exh a u st pipe fr om t h e en gin e
exh a u st m a n ifold. Disca r d t h e sea l (4.0L en gin e,
on ly).
(5) Su ppor t t h e t r a n sm ission a n d r em ove t h e r ea r
cr ossm em ber.
EX H AU ST SY ST EM DI AGN OSI S CH ART
POSSIBLE CAUSE
1. Leaks at pipe joints.
2. Rusted or blown out muffler.
3. Broken or rusted out exhaust
pipe.
4. Exhaust pipe leaking at manifold
flange.
5. Exhaust manifold cracked or
broken.
6. Leak between exhaust manifold
and cylinder head.
7. Catalytic converter rusted or
blown out.
8. Restriction in exhaust system.
1. Tighten clamps/bolts at leaking
joints.
2. Replace muffler. Inspect exhaust
system.
3. Replace exhaust pipe.
4. Tighten/replace flange attaching
nuts/bolts.
5. Replace exhaust manifold.
6. Tighten exhaust manifold to
cylinder head bolts.
7. Replace catalytic converter assy.
8. Remove restriction, if possible.
Replace restricted part if necessary.
(6) Rem ove t h e cla m p n u t s a n d cla m p (F ig. 2). To
r em ove t h e exh a u st pipe fr om t h e ca t a lyt ic con ver t er,
a pply h ea t u n t il t h e m et a l becom es ch er r y r ed. Dis-
con n ect t h e exh a u st pipe fr om t h e ca t a lyt ic con ver t er
(F ig. 2). Rem ove t h e exh a u st pipe.
INSTALLA TION
(1) Assem ble exh a u st pipe t o m a n ifold a n d ca t a -
lyt ic con ver t er loosely t o per m it pr oper a lign m en t of
a ll pa r t s.
(2) Use a n ew cla m p a n d t igh t en t h e n u t s t o 61
N·m (45 ft . lbs.) t or qu e.
(3) Con n ect t h e exh a u st pipe t o t h e en gin e exh a u st
m a n ifold. In st a ll a n ew sea l bet ween t h e exh a u st
m a n ifold a n d t h e exh a u st pipe (4.0L en gin e on ly).
Tigh t en t h e n u t s t o 31 N·m (23 ft . lbs.) t or qu e (F ig.
2).
(4) In st a ll t h e r ea r
t igh t en t h e fou r (4) cr ossm em ber t o r ea r m ou n t n u t s
t o 22 N·m (16 ft . lbs.) In st a ll a n d t igh t en t h e cr oss-
m em ber t o sill bolt s t o 42 N·m (31 ft . lbs.) t or qu e.
Rem ove t h e su ppor t fr om t h e t r a n sm ission .
(5) Coa t t h e oxygen sen sor wit h a n t i-seize com -
pou n d. In st a ll t h e sen sor a n d t igh t en t h e n u t t o 27
N·m (20 ft . lbs.) t or qu e.
(6) Lower t h e veh icle.
CORRECTION
cr ossm em ber. In st a ll a n d
X J