Dodge RAM TRUCK 1500 1995 Service Manual page 850

9 - 6 ENGINES
B R
If bubbles are not visible, install a radiator pres­
sure tester and pressurize the coolant system.
If a cylinder is leaking combustion pressure into
the water jacket, the tester pointer will pulsate with
every combustion stroke of the cylinder.
CYLINDER COMBUSTION PRESSURE LEAKAGE
TEST
The combustion pressure leakage test provides an
accurate means for determining engine condition.
Combustion pressure leakage testing will detect:
© Exhaust and intake valve leaks (improper seat­
ing).
® Leaks between adjacent cylinders or into water
jacket.
• Any causes for combustion/compression pressure
loss.
WARNING: DO NOT R E M O V E THE RADIATOR C A P
WITH THE S Y S T E M HOT AND UNDER P R E S S U R E
B E C A U S E S E R I O U S B U R N S FROM COOLANT CAN
OCCUR.
Check the coolant level and fill as required. DO
NOT install the radiator cap.
Start and operate the engine until it attains nor­
mal operating temperature, then turn the engine
OFF
Remove the spark plugs.
Remove the oil filler cap.
Remove the air cleaner.
Calibrate the tester according to the manufactur­
er's instructions. The shop air source for testing
should maintain 483 kPa (70 psi) minimum, 1 379
kPa (200 psi) maximum and 552 kPa (80 psi) recom­
mended.
Perform the test procedures on each cylinder ac­
cording to the tester manufacturer's instructions.
While testing, listen for pressurized air escaping
through the throttle body, tailpipe and oil filler cap
opening. Check for bubbles in the radiator coolant.
All gauge pressure indications should be equal,
with no more than 25% leakage.
FOR EXAMPLE: At 552 kPa (80 psi) input pres­
sure, a minimum of 414 kPa (60 psi) should be main­
tained in the cylinder.
Refer to the Cylinder Combustion Pressure Leak­
age Test Diagnosis chart.
INSPECTION (ENGINE OIL LEAKS IN GENERAL)
Begin with a through visual inspection of the en­
gine, particularly at the area of the suspected leak. If
an oil leak source is not readily identifiable, the fol­
lowing steps should be followed:
(1) Do not clean or degrease the engine at this
time because some solvents may cause rubber to
swell, temporarily stopping the leak.
(2) Add an oil soluble dye (use as recommended by
manufacturer). Start the engine and let idle for ap­
proximately 15 minutes. Check the oil dipstick to
make sure the dye is thoroughly mixed as indicated
with a bright yellow color under a black light.
(3) Using a black light, inspect the entire engine
for fluorescent dye, particularly at the suspected area
of oil leak. If the oil leak is found and identified, re­
pair per service manual instructions.
(4) If dye is not observed, drive the vehicle at var­
ious speeds for approximately 24km (15 miles), and
repeat step (3).
If the oil leak source is not positively identi­
fied at this time, proceed with the air leak detec­
tion test method as follows:
(1) Disconnect the breather cap to air cleaner hose
at the breather cap end. Cap or plug breather cap
nipple.
(2) Remove the PCV valve from the cylinder head
cover. Cap or plug the PCV valve grommet.
(3) Attach an air hose with pressure gauge and
regulator to the dipstick tube.
CAUTION: Do not subject the engine assembly to
more than 20.6 kpa (3 PSI) of test pressure.
(4) Gradually apply air pressure from 1 psi to 2.5
psi maximum while applying soapy water at the sus­
pected source. Adjust the regulator to the suitable
test pressure that provide the best bubbles which
will pinpoint the leak source. If the oil leak is de­
tected and identified, repair per service manual pro­
cedures.
(5) If the leakage occurs at the rear oil seal area,
refer to the section, Inspection for Rear Seal Area
Leak. :
(6) If no leaks are detected, turn off the air supply
and remove the air hose and all plugs and caps. In­
stall the PCV valve and breather cap hose. Proceed
to step 7.
(7) Clean the oil off the suspect oil leak area using
a suitable solvent. Drive the vehicle at various
speeds approximately 24 km (15 miles). Inspect the
engine for signs of an oil leak by using a black light.
INSPECTION FOR REAR SEAL AREA LEAKS
Since it is sometimes difficult to determine the
source of an oil leak in the rear seal area of the en­
gine, a more involved inspection is necessary. The fol­
lowing steps should be followed to help pinpoint the
source of the leak.
If the leakage occurs at the crankshaft rear oil seal
area:
(1) Disconnect the battery.
(2) Raise the vehicle.
(3) Remove torque converter or clutch housing
cover and inspect rear of block for evidence of oil.
Use a black light to check for the oil leak: