Jeep Cherokee 1999 Electronic Service Manual page 1066

X J
DI SASSEM BLY AN D ASSEM BLY (Cont inue d)
Fig. 68 Measurement of Valve Seat Runout
vice va lves wit h over size st em s a r e a va ila ble in 0.076
m m (0.003 in ch ) a n d 0.381 m m (0.015 in ch ) in cr e-
m en t s.
Cor r espon din g over size va lve st em sea ls a r e a lso
a va ila ble a n d m u st be u sed wit h va lves h a vin g 0.381
m m (0.015 in ch ) over size st em s, 0.076m m (.003in .)
over size st em s do n ot r equ ir e over size sea ls.
NOTE: If the valve guides are reamed oversize, the
valve seats must be ground to ensure that the valve
seat is concentric to the valve guide.
VALVE STEM-TO-GUIDE CLEARANCE
MEASUREMENT
Va lve st em -t o-gu ide clea r a n ce m a y be m ea su r ed by
eit h er of t h e followin g t wo m et h ods.
PREFERRED METHOD:
(1) Rem ove t h e va lve fr om t h e h ea d.
(2) Clea n t h e va lve st em gu ide bor e wit h solven t
a n d a br ist le br u sh .
(3) In ser t a t elescopin g ga u ge in t o t h e va lve st em
gu ide bor e a ppr oxim a t ely 9.525 m m (.375 in ch ) fr om
t h e va lve spr in g side of t h e h ea d (F ig. 69).
(4) Rem ove a n d m ea su r e t elescopin g ga u ge wit h a
m icr om et er.
(5) Repea t t h e m ea su r em en t wit h con t a ct s len gt h -
wise t o en gin e cylin der h ea d.
(6) Com pa r e t h e cr osswise t o len gt h wise m ea su r e-
m en t s t o det er m in e ou t -of-r ou n dn ess. If t h e m ea su r e-
m en t s differ by m or e t h a n 0.0635 m m (0.0025 in .),
r ea m t h e gu ide bor e t o a ccom m oda t e a n over size
va lve st em .
(7) Com pa r e t h e m ea su r ed va lve gu ide bor e dia m -
et er wit h specifica t ion s (7.95-7.97 m m or 0.313-0.314
in ch ). If t h e m ea su r em en t differ s fr om specifica t ion
by m or e t h a n 0.076 m m (0.003 in ch ), r ea m t h e gu ide
bor e t o a ccom m oda t e a n over size va lve st em .
Fig. 69 Measurement of Valve Guide Bore Diameter
ALTERNA TIVE METHOD:
(1) Use a dia l in dica t or t o m ea su r e t h e la t er a l
m ovem en t of t h e va lve st em (st em -t o-gu ide clea r-
a n ce). Th is m u st be don e wit h t h e va lve in st a lled in
it s gu ide a n d ju st off t h e va lve sea t (F ig. 70).
(2) Cor r ect clea r a n ce
(0.001-0.003 in ch ). If in dica t ed m ovem en t exceeds t h e
specifica t ion r ea m t h e va lve gu ide t o a ccom m oda t e
a n over size va lve st em .
NOTE: Valve seats must be ground after reaming
the valve guides to ensure that the valve seat is
concentric to the valve guide.
Fig. 70 Measurement of Lateral Movement Of Valve
2.5L ENGINE
is 0.025-0.0762
Stem
9 - 49
m m