Dodge ram truck 3500 1996 Service Manual page 998

I - 8 ENGINE
BR
DIAGNOSIS AND TESTING (Continued)
• An engine cylinder head gasket leaking between
adjacent cylinders is indicated by a loss of power
and/or engine misfire.
• An engine cylinder head gasket leaking between
a cylinder and an adjacent water jacket is indicated
by coolant foaming or overheating and loss of coolant.
CYLINDER-TO-CYLINDER LEAKAGE TEST
To determine i f an engine cylinder head gasket is
leaking between adjacent cylinders, follow the proce­
dures outlined in Cylinder Compression Pressure
Test. An engine cylinder head gasket leaking between
adjacent cylinders will result in approximately a
50-70% reduction in compression pressure.
CYLINDER-TO-WATER JACKET LEAKAGE
WEST
WARNING: USE EXTREME CAUTION WHEN THE
ENGINE I S OPERATING. DO NOT STAND IN A
DIRECT LINE
W I T H
THE FAN. DO NOT PUT YOUR
HANDS NEAR THE PULLEYS, BELTS, O R T H E F A N .
DO NOT WEAR LOOSE CLOTHING.
Remove the radiator cap.
Start the engine and allow i t to warm up until the
engine thermostat opens.
I f a large combustion/compression pressure leak
exists, bubbles will be visible in the coolant.
If bubbles are not visible, install a radiator pres­
sure tester and pressurize the coolant system.
I f 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 REMOVE THE RADIATOR CAP
WITH THE SYSTEM HOT AND UNDER P R E S S U R E .
SERIOUS BURNS FROM HOT. COOLANT CAN
OCCUR.
Check the coolant level and fill as required. DO
NOT install the radiator cap.
Start and operate the engine until i t attains nor­
mal ' operating temperature, then turn OFF the
engine. '
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 procedure on each cylinder accord­
ing to the tester manufacturer's instructions. While
testing, listen for pressurized air escaping through
the throttle body, tailpipe or oil filler cap opening.
Check for bubbles in the radiator coolant.
All gauge pressure indications should be equal,
with no more than 25% leakage.
F O R E X A M P L E : 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
engine, particularly at the area of the suspected leak.
I f an oil leak source. is not readily identifiable, the
following 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
approximately 15 minutes. Check the oil dipstick to
be sure the dye is thoroughly mixed as indicated
with a bright yellow color under a black light source.
(3) Using a black light, inspect the entire engine
for fluorescent dye, particularly at the suspected area
of oil leak. I f the oil leak is found and identified,
repair per service manual instructions.
(4) I f dye is not observed, drive the vehicle at var­
ious speeds for approximately 24km (15 miles), and
repeat previous step.
(5) I f the oil leak source is not positively identified
at this time, proceed with the air leak detection test
method as follows:
(6) Disconnect the breather cap to air cleaner hose
at the breather cap end. Cap or plug breather cap
nipple.
(7) Remove the PCV valve from the cylinder head
cover. Cap or plug the PCV valve grommet.
(8) 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.
(9) Gradually apply air pressure from 1 psi to 2.5
psi maximum while applying soapy water at the sus-