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DI AGN OSI S AN D T EST I N G (Cont inue d)
CYLINDER-TO-CYLINDER LEAKAGE TEST
To det er m in e if a n en gin e cylin der h ea d ga sket is
lea kin g bet ween a dja cen t cylin der s; follow t h e pr oce-
du r es ou t lin ed in Cylin der Com pr ession P r essu r e
Test . An en gin e cylin der h ea d ga sket lea kin g bet ween
a dja cen t cylin der s will r esu lt in a ppr oxim a t ely a
50-70% r edu ct ion in com pr ession pr essu r e.
CYLINDER-TO-WA TER JACKET LEAKAGE TEST
WARNING: USE EXTREME CAUTION WHEN THE
ENGINE IS OPERATING. DO NOT STAND IN A
DIRECT LINE WITH THE FAN. DO NOT PUT YOUR
HANDS NEAR THE PULLEYS, BELTS OR THE FAN.
DO NOT WEAR LOOSE CLOTHING.
Rem ove t h e r a dia t or ca p.
St a r t t h e en gin e a n d a llow it t o wa r m u p u n t il t h e
en gin e t h er m ost a t open s.
If a la r ge com bu st ion /com pr ession pr essu r e lea k
exist s, bu bbles will be visible in t h e coola n t .
If bu bbles a r e n ot visible, in st a ll a r a dia t or pr es-
su r e t est er a n d pr essu r ize t h e coola n t syst em .
If a cylin der is lea kin g com bu st ion pr essu r e in t o
t h e wa t er ja cket , t h e t est er poin t er will pu lsa t e wit h
ever y com bu st ion st r oke of t h e cylin der.
CYLINDER COMBUSTION PRESSURE LEAKAGE
TEST
Th e com bu st ion pr essu r e lea ka ge t est pr ovides a n
a ccu r a t e m ea n s for det er m in in g en gin e con dit ion .
Com bu st ion pr essu r e lea ka ge t est in g will det ect :
CY LI N DER COM BU ST I ON PRESSU RE LEAK AGE DI AGN OSI S CH ART
CONDITION
AIR ESCAPES THROUGH
THROTTLE BODY
AIR ESCAPES THROUGH
TAILPIPE
AIR ESCAPES THROUGH
RADIATOR
MORE THAN 50% LEAKAGE
FROM ADJACENT CYLINDERS
MORE THAN 25% LEAKAGE AND
AIR ESCAPES THROUGH OIL
FILLER CAP OPENING ONLY
• E xh a u st a n d in t a ke va lve lea ks (im pr oper sea t -
in g).
• Lea ks bet ween a dja cen t cylin der s or in t o wa t er
ja cket .
• An y ca u ses for com bu st ion /com pr ession pr essu r e
loss.
(1) Ch eck t h e coola n t level a n d fill a s r equ ir ed. DO
NOT in st a ll t h e r a dia t or ca p.
(2) St a r t a n d oper a t e t h e en gin e u n t il it a t t a in s
n or m a l oper a t in g t em per a t u r e, t h en t u r n t h e en gin e
OF F.
(3) Rem ove t h e spa r k plu gs.
(4) Rem ove t h e oil filler ca p.
(5) Rem ove t h e a ir clea n er.
(6) Ca libr a t e t h e t est er a ccor din g t o t h e m a n u fa c-
t u r er 's in st r u ct ion s. Th e sh op a ir sou r ce for t est in g
sh ou ld m a in t a in 483 kP a (70 psi) m in im u m , 1,379
kP a (200 psi) m a xim u m a n d 552 kP a (80 psi) r ecom -
m en ded.
(7) P er for m t h e t est pr ocedu r es on ea ch cylin der
a ccor din g t o t h e t est er m a n u fa ct u r er 's in st r u ct ion s.
Wh ile t est in g, list en for pr essu r ized a ir esca pin g
t h r ou gh t h e t h r ot t le body, t a ilpipe a n d oil filler ca p
open in g. Ch eck for bu bbles in t h e r a dia t or coola n t .
All ga u ge pr essu r e in dica t ion s sh ou ld be equ a l,
wit h n o m or e t h a n 25% lea ka ge.
F OR EXAMP LE: At 552 kP a (80 psi) in pu t pr es-
su r e, a m in im u m of 414 kP a (60 psi) sh ou ld be m a in -
t a in ed in t h e cylin der.
Refer t o t h e Cylin der Com bu st ion P r essu r e Lea k-
a ge Test Dia gn osis ch a r t .
POSSIBLE CAUSE
Intake valve bent, burnt, or not
seated properly
Exhaust valve bent, burnt, or not
seated properly
Head gasket leaking or cracked
cylinder head or block
Head gasket leaking or crack in
cylinder head or block between
adjacent cylinders
Stuck or broken piston rings;
cracked piston; worn rings and/or
cylinder wall
ENGINE
CORRECTION
Inspect valve and valve seat.
Reface or replace, as necessary
Inspect valve and valve seat.
Reface or replace, as necessary
Remove cylinder head and inspect.
Replace defective part
Remove cylinder head and inspect.
Replace gasket, head, or block as
necessary
Inspect for broken rings or piston.
Measure ring gap and cylinder
diameter, taper and out-of-round.
Replace defective part as necessary
9 - 9
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