engine is a double over head camshaft with hydraulic
lifters and four valve per cylinder design. The engine
is free-wheeling; meaning it has provisions for piston-
to-valve clearance. However valve-to-valve interfer-
ence

can

occur,

camshafts

are

rotated

independently.

The cylinders are numbered from front of the

engine to the rear. The firing order is 1–3–4–2.

The engine identification number is located on the

rear of the cylinder block (Fig. 1).

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 gage adaptor Special Tool

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

(7) Crank

engine

until

maximum

pressure

reached on gage. Record this pressure as #1 cylinder
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.

Fig. 1 ENGINE IDENTIFICATION

1 - ENGINE IDENTIFICATION

ENGINE 2.4L

9 - 3

ENGINE DIAGNOSIS - PERFORMANCE

CONDITION

POSSIBLE CAUSE

CORRECTION

ENGINE WILL NOT START

1. Weak battery.

1. Test battery. Charge or replace
as necessary. (Refer to 8 -
ELECTRICAL/BATTERY SYSTEM -
DIAGNOSIS AND TESTING)

2. Corroded or loose battery
connections.

2. Clean and tighten battery
connections. Apply a coat of light
mineral grease to terminals.

3. Faulty starter.

3. Test starting system. (Refer to 8 -
ELECTRICAL/STARTING -
DIAGNOSIS AND TESTING)

4. Faulty coil(s) or control unit.

4. Test and replace as needed.
(Refer to Appropriate Diagnostic
Information)

5. Incorrect spark plug gap.

5. Set gap. (Refer to 8 -
ELECTRICAL/IGNITION CONTROL
- SPECIFICATIONS)

6. Contamination in fuel system.

6. Clean system and replace fuel
filter.

7. Faulty fuel pump.

7. Test fuel pump and replace as
needed. (Refer to Appropriate
Diagnostic Information)

8. Incorrect engine timing.

8. Check for a skipped timing
belt/chain.

ENGINE STALLS OR IDLES
ROUGH

1. Idle speed too low.

1. Test minimum air flow. (Refer to
Appropriate Diagnostic Information)

2. Incorrect fuel mixture.

2. (Refer to Appropriate Diagnostic
Information)

3. Intake manifold leakage.

3. Inspect intake manifold, manifold
gasket, and vacuum hoses.

4. Faulty ignition coil(s).

4. Test and replace as necessary.
(Refer to Appropriate Diagnostic
Information)

9 - 4

ENGINE 2.4L

ENGINE 2.4L (Continued)

CONDITION

POSSIBLE CAUSE

CORRECTION

ENGINE LOSS OF POWER

1. Dirty or incorrectly gapped plugs.

1. Clean plugs and set gap.

2. Contamination in fuel system.

2. Clean system and replace fuel
filter.

3. Faulty fuel pump.

3. Test and replace as necessary.
(Refer to Appropriate Diagnostic
Information)

4. Incorrect valve timing.

4. Correct valve timing.

5. Leaking cylinder head gasket.

5. Replace cylinder head gasket.

6. Low compression.

6. Test compression of each
cylinder.

7. Burned, warped, or pitted valves.

7. Replace valves.

8. Plugged or restricted exhaust
system.

8. Perform exhaust restriction test.
(Refer to 11 - EXHAUST SYSTEM -
DIAGNOSIS AND TESTING) Install
new parts, as necessary.

9. Faulty ignition coil(s).

9. Test and replace as necessary.
(Refer to Appropriate Diagnostic
Information)

ENGINE MISSES ON
ACCELERATION

1. Dirty or incorrectly gapped spark
plugs.

1. Clean spark plugs and set gap.

2. Contamination in Fuel System.

2. Clean fuel system and replace
fuel filter.

3. Burned, warped, or pitted valves.

3. Replace valves.

4. Faulty ignition coil(s).

4. Test and replace as necessary.
(Refer to Appropriate Diagnostic
Information)

ENGINE MISSES AT HIGH SPEED

1. Dirty or incorrect spark plug gap.

1. Clean spark plugs and set gap.

2. Faulty ignition coil(s).

2. Test and replace as necessary.
(Refer to Appropriate Diagnostic
Information)

3. Dirty fuel injector(s).

Test and replace as necessary.
(Refer to Appropriate Diagnostic
Information)

4. Contamination in fuel system.

4. Clean system and replace fuel
filter.

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.

ENGINE 2.4L

9 - 5

ENGINE 2.4L (Continued)

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, with 552 kPa (80 psi) rec-
ommended.

Perform the test procedures on each cylinder

according 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 coolant.

All gauge pressure indications should be equal,

with no more than 25% leakage per cylinder.

FOR EXAMPLE: At 552 kPa (80 psi) input pres-

sure, a minimum of 414 kPa (60 psi) should be main-
tained in the cylinder.

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.
(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.

9 - 6

ENGINE 2.4L

ENGINE 2.4L (Continued)

Content .. 420 421 422 423 ..