ING) - MECHANICAL and (Refer to 9 - ENGINE -
DIAGNOSIS AND TESTING) - PERFORMANCE for
possible causes and corrections of malfunctions. Refer
to the appropriate Diagnostic Information for fuel
system diagnosis.

Additional tests and diagnostic procedures may be

necessary for specific engine malfunctions that can-
not be isolated with the Engine Diagnosis charts.
Information concerning additional tests and diagno-
sis is provided within the following:

• Cylinder Compression Pressure Test

• Cylinder Combustion Pressure Leakage Test

• Cylinder Head Gasket Failure Diagnosis

• Intake Manifold Leakage Diagnosis

• Hydraulic Tappet Noise Diagnosis

• Engine Oil Leak Inspection

Fig. 1 8.3L V-10 Engine

Fig. 2 Engine Identification

1 - VIN LOCATION
2 - ENGINE SERIAL NUMBER

ENGINE

9 - 3

ENGINE DIAGNOSIS - PERFORMANCE

CONDITION

POSSIBLE CAUSES

CORRECTION

ENGINE WILL NOT
CRANK

1. Weak or discharged battery.

1. Charge or replace battery as necessary.
(Refer to 8 - ELECTRICAL/BATTERY
SYSTEM - DIAGNOSIS AND TESTING).
Check charging system. Refer to the
appropriate Diagnostic Information for
charging system diagnosis.

2. Corroded or loose battery con-
nections.

2. Clean/tighten battery/starter connections.

3. Faulty starter or related circuits.

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

4. Seized accessory drive compo-
nent.

4. Remove accessory drive belt and
attempt to start engine. If engine cranks,
repair/replace seized component.

5. Engine internal mechanical failure
or hydrostatic lock.

5. (Refer to 9 - ENGINE - STANDARD
PROCEDURE - HYDROSTATIC LOCKED
ENGINE).

ENGINE CRANKS BUT
WILL NOT START

1. No spark.

1. Check for spark. Refer to the appropri-
ate Diagnostic Information for ignition sys-
tem diagnosis.

2. No fuel.

2. Perform fuel pressure test. Refer to the
appropriate Diagnostic Information for fuel
system diagnosis.

3. Low or no engine compression.

3. Perform cylinder compression test.
(Refer to 9 - ENGINE - DIAGNOSIS AND
TESTING - CYLINDER COMPRESSION
PRESSURE TEST).

ENGINE LOSS OF
POWER

1. Worn or incorrect gapped spark
plugs.

1. Replace spark plugs or set gap.

2. Dirt or water in fuel system.

2. Clean system and replace fuel filter.

3. Faulty fuel pump.

3. Replace fuel pump.

4. Incorrect valve timing.

4. Correct valve timing.

5. Blown cylinder head gasket(s).

5. Replace cylinder head gasket(s).

6. Low compression.

6. Test cylinder compression. (Refer to 9 -
ENGINE - DIAGNOSIS AND TESTING -
CYLINDER COMPRESSION PRESSURE
TEST)

7. Burned, warped, or pitted valves.

7. Install new or reface valves as neces-
sary.

8. Plugged or restricted exhaust.

8. Replace parts as necessary.

9. Faulty ignition cables.

9. Replace ignition cables as necessary.

10. Faulty coil(s).

10. Test and replace as necessary.

9 - 4

ENGINE

ENGINE - 8.3L (Continued)

CONDITION

POSSIBLE CAUSES

CORRECTION

ENGINE STALLS OR
ROUGH IDLE

1. Carbon buildup on throttle plate.

1. Remove throttle body and de-carbon.

2. Engine idle speed too low.

2. Check Idle Air Control circuit. Refer to
the appropriate Diagnostic Information for
IAC motor testing.

3. Worn or incorrectly gapped spark
plugs.

3. Replace spark plugs or set gap.

4. Faulty or crossed ignition cables.

4. Check for correct firing order or replace
ignition cables as necessary.

5. Faulty coil(s).

5. Test and replace as necessary.

6. Intake manifold vacuum leak.

6. Inspect intake manifold gasket and vac-
uum hoses. Replace as necessary.

ENGINE MISSES ON
ACCELERATION

1. Worn or incorrectly gapped spark
plugs.

1. Replace spark plugs or set gap.

2. Faulty ignition cables.

2. Replace ignition cables as necessary.

3. Dirt or water in fuel system.

3. Clean system and replace fuel filter.

4. Burned, warped, or pitted valves.

4. Install new or reface valves as neces-
sary.

5. Faulty coil(s).

5. Test and replace as necessary.

ENGINE DIAGNOSIS - MECHANICAL

CONDITION

POSSIBLE CAUSES

CORRECTION

NOISY VALVES

1. High or low oil level in crank-
case.

1. Check for correct oil level. Adjust oil
level by draining or adding as needed.

2. Thin or diluted oil.

2. Change oil and filter.

3. Low oil pressure.

3. Check engine oil level. If OK, perform
oil pressure test. (Refer to 9 - ENGINE/
LUBRICATION - DIAGNOSIS AND TEST-
ING).

4. Dirt in tappets/lash adjusters.

4. Clean/replace hydraulic tappets/lash
adjusters.

5. Bent push rod(s).

5. Replace push rod(s) as necessary.

6. Worn rocker arms.

6. Replace worn rocker arms and inspect
oil supply to rocker arms.

7. Worn tappets/lash adjusters.

7. Replace hydraulic tappets/hydraulic lash
adjusters.

8. Worn valve guides.

8. Ream and install new valves with over-
size stems.

9. Excessive runout of valve seats
on valve faces.

9. Grind valve seats and valves.

ENGINE

9 - 5

ENGINE - 8.3L (Continued)

Content .. 163 164 165 166 ..