Jeep Cherokee 1999 Electronic Service Manual page 1065

9 - 48 2.5L ENGINE
REM OVAL AN D I N STALLAT I ON (Cont inue d)
Fig. 66 Replacement of Rear Crankshaft Oil Seal
INSTALLA TION
(1) Wipe t h e sea l su r fa ce a r ea of t h e cr a n ksh a ft
u n t il it is clea n .
(2) Coa t t h e ou t er lip of t h e r epla cem en t r ea r m a in
bea r in g sea l wit h en gin e oil.
(3) Ca r efu lly posit ion t h e sea l in t o pla ce. Use r ea r
m a in Sea l In st a ller Tool 6271A t o in st a ll t h e sea l
flu sh wit h t h e cylin der block.
CAUTION: The felt lip must be located inside the
flywheel mounting surface. If the lip is not posi-
tioned correctly the flywheel could tear the seal.
(4) In st a ll t h e flywh eel or con ver t er dr ive pla t e.
New bolt s MUST be u sed wh en in st a llin g t h e fly-
wh eel or con ver t er pla t e. Tigh t en t h e n ew bolt s t o 68
N·m (50 ft . lbs.) t or qu e. Tu r n t h e bolt s a n a ddit ion a l
60°.
DI SASSEM BLY AN D ASSEM BLY
VALVE SERVICE
Clea n a ll ca r bon deposit s fr om t h e com bu st ion
ch a m ber s, va lve por t s, va lve st em s, va lve st em
gu ides a n d h ea d.
Clea n a ll gr im e a n d ga sket m a t er ia l fr om t h e
en gin e cylin der h ea d m a ch in ed ga sket su r fa ce.
In spect for cr a cks in t h e com bu st ion ch a m ber s a n d
va lve por t s.
In spect for cr a cks on t h e exh a u st sea t .
In spect for cr a cks in t h e ga sket su r fa ce a t ea ch
coola n t pa ssa ge.
In spect va lves for bu r n ed, cr a cked or wa r ped
h ea ds.
In spect for scu ffed or ben t va lve st em s.
Repla ce va lves displa yin g a n y da m a ge.
VALVE REFACING
(1) Use a va lve r efa cin g m a ch in e t o r efa ce t h e
in t a ke a n d exh a u st va lves t o t h e specified a n gle.
(2) Aft er r efa cin g, a m a r gin of a t lea st 0.787 m m
(0.031 in ch ) m u st r em a in (F ig. 67). If t h e m a r gin is
less t h a n 0.787 m m (0.031 in ch ), t h e va lve m u st be
r epla ced.
Fig. 67 Valve Facing Margin
VALVE SEA T REFACING
(1) In st a ll a pilot of t h e cor r ect size in t h e va lve
gu ide bor e. Refa ce t h e va lve sea t t o t h e specified
a n gle wit h a good dr essin g st on e. Rem ove on ly
en ou gh m et a l t o pr ovide a sm oot h fin ish .
(2) Use t a per ed st on es t o obt a in t h e specified sea t
widt h wh en r equ ir ed.
(3) Con t r ol va lve sea t r u n ou t t o a m a xim u m of
0.0635 m m (0.0025 in .)— (F ig. 68).
VALVE STEM OIL SEAL REPLACEMENT
Va lve st em oil sea ls a r e in st a lled on ea ch va lve
st em t o pr even t r ocker a r m lu br ica t in g oil fr om
en t er in g t h e com bu st ion ch a m ber t h r ou gh t h e va lve
gu ide bor es. On e sea l is m a r ked INT (in t a ke va lve)
a n d t h e ot h er is m a r ked E XH (exh a u st va lve).
Repla ce t h e oil sea ls wh en ever va lve ser vice is per-
for m ed or if t h e sea ls h a ve det er ior a t ed.
VALVE GUIDES
Th e va lve gu ides a r e a n in t egr a l pa r t of t h e en gin e
cylin der h ea d a n d a r e n ot r epla cea ble.
Wh en t h e va lve st em gu ide clea r a n ce is excessive,
t h e va lve gu ide bor es m u st be r ea m ed over size. Ser-
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