Jeep Cherokee 1999 Electronic Service Manual page 1027

9 - 10 ENGINE
DI AGN OSI S AN D T EST I N G (Cont inue d)
ENGINE OIL LEAK INSPECTION
Begin wit h a t h or ou gh visu a l in spect ion of t h e
en gin e, pa r t icu la r ly a t t h e a r ea of t h e su spect ed lea k.
If a n oil lea k sou r ce is n ot r ea dily iden t ifia ble, t h e
followin g st eps sh ou ld be followed:
(1) Do n ot clea n or degr ea se t h e en gin e a t t h is
t im e beca u se som e solven t s m a y ca u se r u bber t o
swell, t em por a r ily st oppin g t h e lea k.
(2) Add a n oil solu ble dye (u se a s r ecom m en ded by
m a n u fa ct u r er ). St a r t t h e en gin e a n d let idle for
a ppr oxim a t ely 15 m in u t es. Ch eck t h e oil dipst ick t o
m a ke su r e t h e dye is t h or ou gh ly m ixed a s in dica t ed
wit h a br igh t yellow color u n der a bla ck ligh t .
(3) Usin g a bla ck ligh t , in spect t h e en t ir e en gin e
for flu or escen t dye, pa r t icu la r ly a t t h e su spect ed a r ea
of oil lea k. If t h e oil lea k is fou n d a n d iden t ified,
r epa ir per ser vice m a n u a l in st r u ct ion s.
(4) If dye is n ot obser ved, dr ive t h e veh icle a t va r-
iou s speeds for a ppr oxim a t ely 24km (15 m iles), a n d
r epea t in spect ion .
(5) If th e o il le a k s o u rc e is n o t p o s itiv e ly
id e n tifie d a t th is tim e , pr oceed wit h t h e a ir lea k
det ect ion t est m et h od.
Air Leak Detection Test Method
(1) Discon n ect t h e br ea t h er ca p t o a ir clea n er h ose
a t t h e br ea t h er ca p en d. Ca p or plu g br ea t h er ca p
n ipple.
(2) Rem ove t h e P CV va lve fr om t h e cylin der h ea d
cover. Ca p or plu g t h e P CV va lve gr om m et .
(3) At t a ch a n a ir h ose wit h pr essu r e ga u ge a n d
r egu la t or t o t h e dipst ick t u be.
CAUTION: Do not subject the engine assembly to
more than 20.6 kpa (3 PSI) of test pressure.
(4) Gr a du a lly a pply a ir pr essu r e fr om 1 psi t o 2.5
psi m a xim u m wh ile a pplyin g soa py wa t er a t t h e su s-
pect ed sou r ce. Adju st t h e r egu la t or t o t h e su it a ble
t est pr essu r e t h a t pr ovide t h e best bu bbles wh ich
will pin poin t t h e lea k sou r ce. If t h e oil lea k is
det ect ed a n d iden t ified, r epa ir per ser vice m a n u a l
pr ocedu r es.
(5) If t h e lea ka ge occu r s a t t h e r ea r oil sea l a r ea ,
r efer t o t h e sect ion , In spect ion for Rea r Sea l Ar ea
Lea k.
(6) If n o lea ks a r e det ect ed, t u r n off t h e a ir su pply
a n d r em ove t h e a ir h ose a n d a ll plu gs a n d ca ps.
In st a ll t h e P CV va lve a n d br ea t h er ca p h ose.
(7) Clea n t h e oil off t h e su spect oil lea k a r ea u sin g
a su it a ble solven t . Dr ive t h e veh icle a t va r iou s
speeds a ppr oxim a t ely 24 km (15 m iles). In spect t h e
en gin e for sign s of a n oil lea k by u sin g a bla ck ligh t .
INSPECTION FOR REAR SEAL AREA LEAKS
Sin ce it is som et im es difficu lt t o det er m in e t h e
sou r ce of a n oil lea k in t h e r ea r sea l a r ea of t h e
en gin e, a m or e in volved in spect ion is n ecessa r y. Th e
followin g st eps sh ou ld be followed t o h elp pin poin t
t h e sou r ce of t h e lea k.
If t h e lea ka ge occu r s a t t h e cr a n ksh a ft r ea r oil sea l
a r ea :
(1) Discon n ect t h e ba t t er y.
(2) Ra ise t h e veh icle.
(3) Rem ove t or qu e con ver t er or clu t ch h ou sin g
cover a n d in spect r ea r of block for eviden ce of oil.
Use a bla ck ligh t t o ch eck for t h e oil lea k:
(a ) Cir cu la r spr a y pa t t er n gen er a lly in dica t es
sea l lea ka ge or cr a n ksh a ft da m a ge.
(b) Wh er e lea ka ge t en ds t o r u n st r a igh t down ,
possible ca u ses a r e a por ou s block, dist r ibu t or sea l,
ca m sh a ft bor e cu p plu gs oil ga lley pipe plu gs, oil
filt er r u n off, a n d m a in bea r in g ca p t o cylin der
block m a t in g su r fa ces.
(4) If n o lea ks a r e det ect ed, pr essu r ize t h e cr a n k-
ca se a s ou t lin ed in t h e, In spect ion (E n gin e oil Lea ks
in gen er a l).
CAUTION: Do not exceed 20.6 kPa (3 psi).
(5) If t h e lea k is n ot det ect ed, ver y slowly t u r n t h e
cr a n ksh a ft a n d wa t ch for lea ka ge. If a lea k is
det ect ed bet ween t h e cr a n ksh a ft a n d sea l wh ile
slowly t u r n in g t h e cr a n ksh a ft , it is possible t h e
cr a n ksh a ft sea l su r fa ce is da m a ged. Th e sea l a r ea on
t h e cr a n ksh a ft cou ld h a ve m in or n icks or scr a t ch es
t h a t ca n be polish ed ou t wit h em er y clot h .
CAUTION: Use extreme caution when crankshaft
polishing is necessary to remove minor nicks and
scratches. The crankshaft seal flange is especially
machined to complement the function of the rear oil
seal.
(6) F or bu bbles t h a t r em a in st ea dy wit h sh a ft
r ot a t ion , n o fu r t h er in spect ion ca n be don e u n t il dis-
a ssem bled.
ENGINE OIL PRESSURE
(1) Discon n ect con n ect or a n d r em ove oil pr essu r e
sen din g u n it .
(2) In st a ll Oil P r essu r e Lin e a n d Ga u ge Tool
C-3292 or equ iva len t . St a r t en gin e a n d r ecor d pr es-
su r e. Refer t o Oil P r essu r e in E n gin e Specifica t ion s
for t h e cor r ect pr essu r es.
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