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 MECHANICAL  and PERFORMANCE  charts, for possible causes and corrections of malfunctions. .

For fuel system diagnosis, refer to FUEL SYSTEM article .

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 .
• Engine Cylinder Head Gasket Failure Diagnosis. Refer to DIAGNOSIS AND TESTING - CYLINDER HEAD GASKET .
• Intake Manifold Leakage Diagnosis. Refer to DIAGNOSIS AND TESTING - INTAKE MANIFOLD LEAKS .
• Mechanical Valve Tappet Noise Diagnosis. Refer to DIAGNOSIS AND TESTING - MECHANICAL VALVE TAPPET NOISE DIAGNOSIS 
• Engine Oil Leak Inspection. Refer to ENGINE OIL LEAK INSPECTION .