engines is a single overhead camshaft design with
hydraulic lifters and four valves per cylinder (Fig. 1).
The engine does not have provisions for a free wheel-
ing valve train.

The cylinders are numbered from front to rear,

with the right bank odd numbered, and the left bank
even numbered (Fig. 2). The firing order is 1–2–3–4–
5–6.

The engine identification number is located on the

rear of engine block just below the cylinder head
(Fig. 3).

ENGINE

9 - 3

Fig. 1 3.5L Engine

9 - 4

ENGINE

ENGINE 3.5L (Continued)

DIAGNOSIS AND TESTING

DIAGNOSIS AND TESTING - ENGINE
DIAGNOSIS - INTRODUCTION

Engine diagnosis is helpful in determining the

causes of malfunctions not detected and remedied by
routine maintenance.

These malfunctions may be classified as either

mechanical (e.g., a strange noise), or performance
(e.g., engine idles rough and stalls).

Refer to the Engine Mechanical and the Engine

Performance diagnostic charts, for possible causes
and corrections of malfunctions (Refer to 9 - ENGINE
- DIAGNOSIS AND TESTING - MECHANICAL)
(Refer to 9 - ENGINE - DIAGNOSIS AND TESTING
- PERFORMANCE).

For fuel system diagnosis, (Refer to 14 - FUEL

SYSTEM/FUEL DELIVERY

DIAGNOSIS AND

TESTING).

Additional tests and diagnostic procedures may be

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

• Cylinder Compression Pressure Test

• Cylinder Combustion Pressure Leakage Test

• Engine Cylinder Head Gasket Failure Diagnosis

• Intake Manifold Leakage Diagnosis

• Hydraulic Lash Adjuster Noise Diagnosis

• Engine Oil Leak Inspection

Fig. 2 Cylinder Numbering & Firing Order - 3.5L

Fig. 3 ENGINE IDENTIFICATION

ENGINE

9 - 5

ENGINE 3.5L (Continued)

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 oil and filter.

(b.) Run engine to operating
temperature.

(c.) Change oil and filter again.

4. Low oil pressure.

4. Check and correct engine oil
level.

5. Dirt in tappets/lash adjusters.

5. Replace rocker arm/hydraulic
lash adjuster assembly.

6. Worn rocker arms.

6. Inspect oil supply to rocker arms.

7. Worn tappets/lash adjusters.

7. Install new rocker arm/hydraulic
lash adjuster assembly.

8. Worn valve guides.

8. Ream guides and install new
valves with oversize stems.

9. Excessive runout of valve seats
on valve faces.

9. Grind valve seats and valves.

10. Missing adjuster pivot.

10. Replace rocker arm/hydraulic
lash adjuster assembly.

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. Thick / Thin or diluted oil.

3. Change oil to correct viscosity.

3. (a.) Change oil and filter.

(b.) Run engine to operating
temperature.

(c.) Change oil and filter again.

4. Excessive bearing clearance.

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

5. Connecting rod journal
out-of-round.

5. Replace crankshaft or grind
surface.

6. Misaligned connecting rods.

6. Replace bent connecting rods.

9 - 6

ENGINE

ENGINE 3.5L (Continued)

Content .. 237 238 239 240 ..