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Chrysler Town, Dodge Caravan. Manual - part 297

DIAGNOSIS AND TESTING - ENGINE DIAGNOSIS - MECHANICAL

CONDITION

POSSIBLE CAUSES

CORRECTION

NOISY VALVES

1. High or low oil level in
crankcase.

1. Check and correct engine oil
level.

2. Thin or diluted oil.

2. Change oil to correct viscosity.

3. Thick oil

3. (a) Change engine oil and filter.

(b) Run engine to operating
temperature.

4. Low oil pressure.

4. Check and correct engine oil
pressure problem.

5. Dirt in hydraulic lifters/lash
adjusters.

5. Replace hydraulic lifters/lash
adjusters.

6. Worn rocker arms.

6. Inspect oil supply to rocker arms.

7. Worn hydraulic lifters/lash
adjusters.

7. Replace hydraulic lifters/lash
adjusters.

8. Worn valve guides.

8. Replace cylinder head assembly.

9. Excessive runout of valve seats
on valve faces.

9. Grind valve seats and valves.

CONNECTING ROD NOISE

1. Insufficient oil supply.

1. Check engine oil level.

2. Low oil pressure.

2. Check engine oil level. Inspect oil
pump relief valve and spring.

3. Thin or diluted oil.

3. Change oil to correct viscosity.

4. Thick oil

4. (a) Change engine oil and filter.

(b) Run engine to operating
temperature.

5. Excessive bearing clearance.

5. Measure bearings for correct
clearance. Repair as necessary.

6. Connecting rod journal
out-of-round.

6. Replace crankshaft or grind
surface.

7. Misaligned connecting rods.

7. Replace bent connecting rods.

9 - 6

ENGINE 2.4L

ENGINE 2.4L (Continued)

CONDITION

POSSIBLE CAUSES

CORRECTION

MAIN BEARING NOISE

1. Insufficient oil supply.

1. Check engine oil level.

2. Low oil pressure.

2. Check engine oil level. Inspect oil
pump relief valve and spring.

3. Thin or diluted oil.

3. Change oil to correct viscosity.

4. Thick oil

4. (a) Change engine oil and filter.

(b) Run engine to operating
temperature.

5. Excessive bearing clearance.

5. Measure bearings for correct
clearance. Repair as necessary.

6. Excessive end play.

6. Check thrust bearing for wear on
flanges.

7. Crankshaft journal out-of-round
or worn.

7. Replace crankshaft or grind
journals.

8. Loose flywheel or torque
converter.

8. Tighten to correct torque.

OIL PRESSURE DROP

1. Low oil level.

1. Check engine oil level.

2. Faulty oil pressure sensor/switch.

2. Replace oil pressure sensor/
switch.

3. Low oil pressure.

3. Check oil pressure sensor/switch
and main bearing oil clearance.

4. Clogged oil filter.

4. Install new oil filter.

5. Worn parts in oil pump.

5. Replace worn parts or pump.

6. Thin or diluted oil.

6. Change oil to correct viscosity.

7. Oil pump relief valve stuck.

7. Remove valve and inspect, clean,
or replace.

8. Oil pump suction tube loose.

8. Remove oil pan and install new
tube or clean, if necessary.

9. Oil pump cover warped or
cracked.

9. Install new oil pump.

10. Excessive bearing clearance.

10. Measure bearings for correct
clearance.

OIL LEAKS

1. Misaligned or deteriorated
gaskets.

1. Replace gasket(s).

2. Loose fastener, broken or porous
metal part.

2. Tighten, repair or replace the
part.

3. Misaligned or deteriorated cup or
threaded plug.

3. Replace as necessary.

ENGINE 2.4L

9 - 7

ENGINE 2.4L (Continued)

CONDITION

POSSIBLE CAUSES

CORRECTION

OIL CONSUMPTION OR SPARK
PLUGS FOULED

1. PCV system malfunction.

1. Check system and repair as
necessary. (Refer to 25 -
EMISSIONS CONTROL/
EVAPORATIVE EMISSIONS/PCV
VALVE - DIAGNOSIS AND
TESTING)

2. Worn, scuffed or broken rings.

2. Hone cylinder bores. Install new
rings.

3. Carbon in oil ring slots.

3. Install new rings.

4. Rings fitted too tightly in grooves.

4. Remove rings and check
grooves. If groove is not proper
width, replace piston.

5. Worn valve guide(s).

5. Replace cylinder head assembly.

6. Valve stem seal(s) worn or
damaged.

6. Replace seal(s).

DIAGNOSIS AND TESTING - ENGINE OIL LEAK
INSPECTION

Begin with a thorough visual inspection of the

engine, particularly at the area of the suspected leak.
If 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
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,
repair as necessary.

(4) If dye is not observed, drive the vehicle at var-

ious speeds for approximately 24 km (15 miles), and
repeat inspection.

(5) If the oil leak source is not positively

identified at this time, proceed with the air leak
detection test method as follows:

• Disconnect the fresh air hose (make-up air) at

the cylinder head cover and plug or cap the nipple on
the cover.

• Remove the PCV valve hose from the cylinder

head cover. Cap or plug the PCV valve nipple on the
cover.

• Attach an air hose with pressure gauge and reg-

ulator to the dipstick tube.

CAUTION: Do not subject the engine assembly to
more than 20.6 kpa (3 PSI) of test pressure.

• 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 provides the best bubbles which
will pinpoint the leak source. If the oil leak is
detected and identified, repair per service manual
procedures.

• If the leakage occurs at the crankshaft 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.

Remove the air hose, all plugs, and caps. Install the
PCV valve and fresh air hose (make-up air). Proceed
to next step.

(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.

NOTE: If oil leakage is observed at the dipstick tube
to block location; remove the tube, clean and reseal
using Mopar

Stud & Bearing Mount (press fit tube

applications only), and for O-ring style tubes,
remove tube and replace the O-ring seal.

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
engine, a more involved inspection is necessary. The
following 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.

9 - 8

ENGINE 2.4L

ENGINE 2.4L (Continued)

(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. If a leak is
present in this area, remove transmission for further
inspection.

(a) Circular spray pattern generally indicates

seal leakage or crankshaft damage.

(b) Where leakage tends to run straight down,

possible causes are a porous block, oil gallery cup
plug, bedplate to cylinder block mating surfaces
and seal bore. See proper repair procedures for
these items.
(4) If no leaks are detected, pressurize the crank-

case as previously described.

CAUTION: Do not exceed 20.6 kPa (3 psi).

(5) If the leak is not detected, very slowly turn the

crankshaft and watch for leakage. If a leak is
detected between the crankshaft and seal while
slowly turning the crankshaft, it is possible the
crankshaft seal surface is damaged. The seal area on
the crankshaft could have minor nicks or scratches
that can be polished out with emery cloth.

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) For bubbles that remain steady with shaft

rotation, no further inspection can be done until dis-
assembled.

(7) After the oil leak root cause and appropriate

corrective action have been identified, replace compo-
nent(s) as necessary.

DIAGNOSIS AND TESTING - CYLINDER
COMPRESSION PRESSURE TEST

The results of a cylinder compression pressure test

can be utilized to diagnose several engine malfunc-
tions.

Ensure the battery is completely charged and the

engine starter motor is in good operating condition.
Otherwise the indicated compression pressures may
not be valid for diagnosis purposes.

(1) Check engine oil level and add oil if necessary.
(2) Drive the vehicle until engine reaches normal

operating temperature. Select a route free from traf-
fic and other forms of congestion, observe all traffic
laws, and accelerate through the gears several times
briskly.

(3) Remove all spark plugs from engine. As spark

plugs are being removed, check electrodes for abnor-
mal firing indicators fouled, hot, oily, etc. Record cyl-
inder number of spark plug for future reference.

(4) Remove the Auto Shutdown (ASD) relay from

the PDC.

(5) Be sure throttle blade is fully open during the

compression check.

(6) Insert compression gauge adaptor Special Tool

8116 or the equivalent, into the #1 spark plug hole in
cylinder head. Connect the 0–500 psi (Blue) pressure
transducer (Special Tool CH7059) with cable adap-
tors to the DRBIII

t. For Special Tool identification,

(Refer to 9 - ENGINE - SPECIAL TOOLS).

(7) Crank

engine

until

maximum

pressure

reached on gauge. Record this pressure as #1 cylin-
der pressure.

(8) Repeat the previous step for all remaining cyl-

inders.

(9) Compression should not be less than 689 kPa

(100 psi) and not vary more than 25 percent from cyl-
inder to cylinder.

(10) If one or more cylinders have abnormally low

compression pressures, repeat the compression test.

(11) If the same cylinder or cylinders repeat an

abnormally low reading on the second compression
test, it could indicate the existence of a problem in
the cylinder in question. The recommended com-
pression pressures are to be used only as a
guide to diagnosing engine problems. An engine
should not be disassembled to determine the
cause of low compression unless some malfunc-
tion is present.

DIAGNOSIS AND TESTING - 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 PRESSURE CAP
WITH THE SYSTEM HOT AND UNDER PRESSURE
BECAUSE SERIOUS BURNS FROM COOLANT CAN
OCCUR.

Check the coolant level and fill as required. DO

NOT install the pressure cap.

Start and operate the engine until it attains nor-

mal operating temperature, then turn the engine
OFF.

Clean spark plug recesses with compressed air.
Remove the spark plugs.
Remove the oil filler cap.
Remove the air cleaner.

ENGINE 2.4L

9 - 9

ENGINE 2.4L (Continued)

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