Jeep Cherokee 1999 Electronic Service Manual page 1109

9 - 92 4.0L ENGINE
CLEAN I N G AN D I N SPECT I ON (Cont inue d)
(6) Adju st t h e n ose of t h e r a m t o a lign t h e poin t er
wit h t h e SE T m a r k on t h e sca le of t h e t est er a n d
t igh t en t h e h ex n u t .
(7) Slowly swin g t h e weigh t ed a r m on t o t h e pu sh
r od.
(8) Rot a t e t h e cu p by t u r n in g t h e h a n dle a t t h e
ba se of t h e t est er clockwise on e r evolu t ion ever y 2
secon ds.
(9) Obser ve t h e lea k-down t im e in t er va l fr om t h e
in st a n t t h e poin t er a lign s wit h t h e START m a r k on
t h e sca le u n t il t h e poin t er a lign s wit h t h e 0.125
m a r k. A n or m a lly fu n ct ion in g t a ppet will r equ ir e
20-110 secon ds t o lea k-down . Disca r d t a ppet s wit h
lea k-down t im e in t er va l n ot wit h in t h is specifica t ion .
Fig. 66 Leak-Down Tester
CYLINDER BLOCK
CLEANING
Th or ou gh ly clea n t h e oil pa n a n d en gin e block ga s-
ket su r fa ces.
Use com pr essed a ir t o clea n ou t :
• Th e ga lley a t t h e oil filt er a da pt or h ole.
• Th e fr on t a n d r ea r oil ga lley h oles.
• Th e feed h oles for t h e cr a n ksh a ft m a in bea r in gs.
On ce t h e block h a s been com plet ely clea n ed, a pply
Loct it e P ST pipe sea la n t wit h Teflon 592 t o t h e
t h r ea ds of t h e fr on t a n d r ea r oil ga lley plu gs. Tigh t en
t h e plu gs t o 34 N·m (25 ft . lbs.) t or qu e.
INSPECTION—CYLINDER BORE
(1) It is m a n da t or y t o u se a dia l bor e ga u ge t o
m ea su r e ea ch cylin der bor e dia m et er (F ig. 67). To
cor r ect ly select t h e pr oper size pist on , a cylin der bor e
ga u ge, ca pa ble of r ea din g in 0.003 m m (.0001 in .)
INCRE ME NTS is r equ ir ed. If a bor e ga u ge is n ot
a va ila ble, do n ot u se a n in side m icr om et er.
(2) Mea su r e t h e in side dia m et er of t h e cylin der
bor e a t t h r ee levels below t op of bor e. St a r t per pen -
Fig. 67 Cylinder Bore Measurement
dicu la r (a cr oss or a t 90 degr ees) t o t h e a xis of t h e
cr a n ksh a ft a n d t h en t a ke t wo a ddit ion a l r ea din g.
(3) Mea su r e t h e cylin der bor e dia m et er cr osswise
t o t h e cylin der block n ea r t h e t op of t h e bor e. Repea t
t h e m ea su r em en t n ea r t h e m iddle of t h e bor e, t h en
r epea t t h e m ea su r em en t n ea r t h e bot t om of t h e bor e.
(4) Det er m in e t a per by su bt r a ct in g t h e sm a ller
dia m et er fr om t h e la r ger dia m et er.
(5) Rot a t e m ea su r in g device 90° a n d r epea t st eps
a bove.
(6) Det er m in e ou t -of-r ou n dn ess by com pa r in g t h e
differ en ce bet ween ea ch m ea su r em en t .
(7) If cylin der bor e t a per does n ot exceed 0.025
m m (0.001 in ch ) a n d ou t -of-r ou n dn ess does n ot
exceed 0.025 m m (0.001 in ch ), t h e cylin der bor e ca n
be h on ed. If t h e cylin der bor e t a per or ou t - of-r ou n d
con dit ion exceeds t h ese m a xim u m lim it s, t h e cylin der
m u st be bor ed a n d t h en h on ed t o a ccept a n over size
pist on . A sligh t a m ou n t of t a per a lwa ys exist s in t h e
cylin der bor e a ft er t h e en gin e h a s been in u se for a
per iod of t im e.
HONING—CYLINDER BORE
Th e h on in g oper a t ion sh ou ld be closely coor din a t ed
wit h t h e fit t in g of pist on s a n d r in gs. Th is will en su r e
specified clea r a n ces a r e m a in t a in ed.
Refer t o St a n da r d Ser vice P r ocedu r es in t h e begin -
n in g of t h is Gr ou p for t h e pr oper h on in g of cylin der
bor es.
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