Jeep Cherokee 1999 Electronic Service Manual page 1108

X J
DI SASSEM BLY AN D ASSEM BLY (Cont inue d)
(14) F ill t h e en gin e wit h clea n lu br ica t ion oil (r efer
t o Gr ou p 0, Lu br ica t ion a n d Ma in t en a n ce).
(15) F ill t h e coolin g syst em .
CLEAN I N G AN D I N SPECT I ON
CYLINDER HEAD
CLEANING
Th or ou gh ly clea n t h e en gin e cylin der h ea d a n d cyl-
in der block m a t in g su r fa ces. Clea n t h e in t a ke a n d
en gin e exh a u st m a n ifold a n d en gin e cylin der h ea d
m a t in g su r fa ces. Rem ove a ll ga sket m a t er ia l a n d ca r-
bon .
Ch eck t o en su r e t h a t n o coola n t or for eign m a t er ia l
h a s fa llen in t o t h e t a ppet bor e a r ea .
Rem ove t h e ca r bon deposit s fr om t h e com bu st ion
ch a m ber s a n d t op of t h e pist on s.
INSPECTION
Use a st r a igh t edge a n d feeler ga u ge t o ch eck t h e
fla t n ess of t h e en gin e cylin der h ea d a n d block m a t in g
su r fa ces.
CYLINDER HEAD COVER
CLEANING
Rem ove a n y or igin a l sea ler fr om t h e cover sea lin g
su r fa ce of t h e en gin e cylin der h ea d a n d clea n t h e
su r fa ce u sin g a fa br ic clea n er.
Rem ove a ll r esidu e fr om t h e sea lin g su r fa ce u sin g
a clea n , dr y clot h .
INSPECTION
In spect t h e en gin e cylin der h ea d cover for cr a cks.
Repla ce t h e cover, if cr a cked.
Th e or igin a l da r k gr ey ga sket m a t er ia l sh ou ld
NOT be r em oved. If sect ion s of t h e ga sket m a t er ia l
a r e m issin g or a r e com pr essed, r epla ce t h e en gin e
cylin der h ea d cover. H owever, sect ion s wit h m in or
da m a ge su ch a s sm a ll cr a cks, cu t s or ch ips m a y be
r epa ir ed wit h a h a n d h eld a pplica t or. Th e n ew m a t e-
r ia l m u st be sm oot h ed over t o m a in t a in ga sket
h eigh t . Allow t h e ga sket m a t er ia l t o cu r e pr ior t o
en gin e cylin der h ea d cover in st a lla t ion .
ROCKER ARMS AND PUSH RODS
CLEANING
Clea n a ll t h e com pon en t s wit h clea n in g solven t .
Use com pr essed a ir t o blow ou t t h e oil pa ssa ges in
t h e r ocker a r m s a n d pu sh r ods.
INSPECTION
In spect t h e pivot su r fa ce a r ea of ea ch r ocker a r m .
Repla ce a n y t h a t a r e scu ffed, pit t ed, cr a cked or
excessively wor n .
In spect t h e va lve st em t ip con t a ct su r fa ce of ea ch
r ocker a r m a n d r epla ce a n y r ocker a r m t h a t is deeply
pit t ed.
In spect ea ch pu sh r od en d for excessive wea r a n d
r epla ce a s r equ ir ed. If a n y pu sh r od is excessively
wor n beca u se of la ck of oil, r epla ce it a n d in spect t h e
cor r espon din g h ydr a u lic t a ppet for excessive wea r.
In spect t h e pu sh r ods for st r a igh t n ess by r ollin g
t h em on a fla t su r fa ce or by sh in in g a ligh t bet ween
t h e pu sh r od a n d t h e fla t su r fa ce.
A wea r pa t t er n a lon g t h e len gt h of t h e pu sh r od is
n ot n or m a l. In spect t h e en gin e cylin der h ea d for
obst r u ct ion if t h is con dit ion exist s.
HYDRAULIC TAPPETS
CLEANING
Clea n ea ch t a ppet a ssem bly in clea n in g solven t t o
r em ove a ll va r n ish , gu m a n d slu dge deposit s.
INSPECTION
In spect for in dica t ion s of scu ffin g on t h e side a n d
ba se of ea ch t a ppet body.
In spect ea ch t a ppet ba se for con ca ve wea r wit h a
st r a igh t edge posit ion ed a cr oss t h e ba se. If t h e ba se is
con ca ve, t h e cor r espon din g lobe on t h e ca m sh a ft is
a lso wor n . Repla ce t h e ca m sh a ft a n d defect ive t a p-
pet s.
LEAK-DOWN TEST
Aft er clea n in g a n d in spect ion , t est ea ch t a ppet for
specified lea k-down r a t e t oler a n ce t o en su r e zer o-la sh
oper a t ion (F ig. 66).
Swin g t h e weigh t ed a r m of t h e h ydr a u lic va lve t a p-
pet t est er a wa y fr om t h e r a m of t h e Lea k-Down
Test er.
(1) P la ce a 7.925-7.950 m m (0.312-0.313 in ch )
dia m et er ba ll bea r in g on t h e plu n ger ca p of t h e t a p-
pet .
(2) Lift t h e r a m a n d posit ion t h e t a ppet (wit h t h e
ba ll bea r in g) in side t h e t est er cu p.
(3) Lower t h e r a m , t h en a dju st t h e n ose of t h e r a m
u n t il it con t a ct s t h e ba ll bea r in g. DO NOT t igh t en
t h e h ex n u t on t h e r a m .
(4) F ill t h e t est er cu p wit h h ydr a u lic va lve t a ppet
t est oil u n t il t h e t a ppet is com plet ely su bm er ged.
(5) Swin g t h e weigh t ed a r m on t o t h e pu sh r od a n d
pu m p t h e t a ppet plu n ger u p a n d down t o r em ove a ir.
Wh en t h e a ir bu bbles cea se, swin g t h e weigh t ed a r m
a wa y a n d a llow t h e plu n ger t o r ise t o t h e n or m a l
posit ion .
4.0L ENGINE 9 - 91