Diagnosis and Testing: 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 ENGINE MECHANICAL  or ENGINE PERFORMANCE  for possible causes and corrections of malfunctions. Refer to FUEL SYSTEM for the fuel system diagnosis.

Additional tests and diagnostic procedures may be necessary for specific engine malfunctions that cannot be isolated with the Service Diagnosis charts. Information concerning additional tests and diagnosis is provided within the following:

• Cylinder Compression Pressure Test: Refer to CYLINDER COMPRESSION PRESSURE TEST .
• Cylinder Combustion Pressure Leakage Test: Refer to CYLINDER COMBUSTION PRESSURE LEAKAGE TEST .
• Cylinder Head Gasket Failure Diagnosis: Refer to CYLINDER HEAD GASKET .
• Intake Manifold Leakage Diagnosis: Refer to MANIFOLD, Intake .
• Lash Adjuster (Tappet) Noise Diagnosis: Refer to LASH ADJUSTER (TAPPET) NOISE DIAGNOSIS .
• Engine Oil Leak Inspection: Refer to ENGINE OIL LEAK INSPECTION .