Service diagnosis is a systematic procedure of investigation to be followed in order to locate and correct an engine
problem. The engine is first considered as a complete unit in its specific application and then the problem is localized to
components or systems; intake, exhaust, cooling, lubrication or injection. Testing procedures will then help analyze the
source of the problem.
PREREQUISITES FOR EFFECTIVE DIAGNOSIS:
1. Knowledge of the principles of operation for both the engine and application systems.
2. Knowledge to perform and understand all procedures In the diagnostic and service manuals.
3. Availability of and the ability to use gauges and diagnostic test equipment.
4. Have available the current Guideline Data for the engine application.
Although the cause of an engine failure may be apparent, very often the real cause Is not found until a repeat failure
occurs. This can be prevented if specific diagnostic action is taken prior to, during and after engine disassembly and
during engine reassembly.
It is also very important that specific diagnostic tests follow engine reassembly prior to and after the engine is placed back
Identification of the symptoms which lead to engine failure is the result of proper service diagnosis. Effective service
diagnosis requires use of the following references:
1. GSS-1460 and GSS-1482 for Agricultural Equipment Applications.
2. ISS-1526 for Pay Line Applications.
3. 1 171 478 R1 for On-Highway Truck Applications.
4. Component Specifications within this Manual.
5. Service Bulletins.
The visual inspections and measurements required will determine not only the need to replace a component but also for
salvage such as the crankcase for cylinder sleeve upper and lower bore inserts.
It is recommended that you follow the steps outlined in the areas listed below when the need to perform engine repairs
becomes necessary. This will avoid unnecessary repairs, pin-point the cause or causes of failure and eliminate repeat
PRIOR TO REMOVAL OF ENGINE FROM CHASSIS OR PERFORMING IN-CHASSIS DISASSEMBLY.
PRIOR TO ENGINE DISASSEMBLY.
DURING ENGINE REASSEMBLY.
DURING ENGINE DISASSEMBLY.
PRIOR TO ENGINE START-UP.
PRIOR TO ENGINE REASSEMBLY.
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