Initial Inspection and Diagnostic Overview

CLOSED-TYPE POSITIVE CRANKCASE VENTILATION SYSTEM
A malfunction in the Positive Crankcase Ventilation (PCV) system can result in the engine having rough idle or loping. Do not attempt to correct this idle condition by performing an idle speed adjustment or by trying to bypass the airflow. Refer to Powertrain Management, for diagnosing a malfunction in the PCV system.

COMPONENT REPAIR/REPLACEMENT
Make sure that the following engine components are not serviceable before replacing damaged or worn engine components:
- Camshafts (6250).
- Crankshaft (6303).
- cylinder block (6010).
- Cylinder heads (6049).
- Exhaust valve (6505) and intake valve (6507).
- Valve guides.

EXHAUST EMISSION CONTROL SYSTEM
To maintain the required exhaust emission levels, the following components must be kept in good operating condition and meet recommended adjustment specifications:
- Engine.
- Fuel system.
- Ignition system.
See Powertrain Management information on the exhaust emission control devices used on this engine. When performing tests, adjustment or service to the engine, fuel system or fuel ignition system, follow the appropriate procedures and specifications.

INSPECTION AND VERIFICATION
1. Check the oil level and condition.
2. Verify the customer concern by starting the engine and listening to it idle.
3. Inspect to determine if any of the following mechanical concerns apply:
- Engine cooling system leaks, oil leaks, or fuel leaks.
- Damaged and/or severely worn parts.
- Loose mounting bolts, studs and nuts.
5. If the inspection reveals obvious concerns that can be readily identified, repair as required.
6. If fault is not visually evident, determine the symptom and proceed to Diagnosis By Symptom.