DETROIT DIESEL 53
If parts are not to be used immediately after cleaning, dip them in a suitable rust preventive compound. The rust
preventive compound should be removed before installing the parts in an engine.
The purpose of parts inspection is to determine which parts can be used and which must be replaced.
Although the engine overhaul specifications given throughout the text will aid in determining which parts should be
replaced, considerable judgment must be exercised by the inspector.
The guiding factors in determining the usability of worn parts, which are otherwise in good condition, is the clearance
between the mating parts and the rate of wear on each of the parts. If it is determined that the rate of wear will maintain
the clearances within the specified maximum allowable until the next overhaul period, the reinstallation of used parts
may be justified. Rate of wear of a part is determined by dividing the amount the part has worn by the hours it has
Many service replacement parts are available in various undersize and/or oversize as well as standard sizes. Also,
service kits for reconditioning certain parts and service sets which include all of the parts necessary to complete a
particular repair job are available.
A complete discussion of the proper methods of precision measuring and inspection are outside the scope of this manual.
However, every shop should be equipped with standard gages, such as dial bore gages, dial indicators, and inside and
In addition to measuring the used parts after cleaning, the parts should be carefully inspected for cracks, scoring,
chipping and other defects.
Following cleaning and inspection, the engine should be assembled using new parts as determined by the inspection.
Use of the proper equipment and tools makes the job progress faster and produces better results. Likewise, a suitable
working space with proper lighting must be provided. The time and money invested in providing the proper tools,
equipment and space will be repaid many times.
Keep the working space, the equipment, tools and engine assemblies and parts clean at all times. The area where
assembly operations take place should, if possible, be located away from the disassembly and cleaning operation. Also,
any machining operations should be removed as far as possible from the assembly area.
Particular attention should be paid to storing of parts and sub-assemblies, after removal and cleaning and prior to
assembly, in such a place or manner as to keep them clean. If there is any doubt as to the cleanliness of such parts, they
should be recleaned. When assembling an engine or any part thereof, refer to the table of torque specifications at the
end of each section for proper bolt, nut and stud torques.
A serviceman can be severely injured if caught in the pulleys, belts or fan of an engine that is accidentally started.
To avoid such a misfortune, take these precautions before starting to work on an engine:
Disconnect the battery from the starting system by removing one or both of the battery cables. With the electrical
circuit disrupted, accidental contact with the starter button will not produce an engine start.
Make sure the mechanism provided at the governor for stopping the engine is in the stop position. This will
mean the governor is in the no-fuel position. The possibility of the engine firing by accidentally turning the fan or, in
the case of vehicle application, by being bumped by another vehicle is minimized.
Some Safety Precautions To Observe When Working On The Engine
1. Consider the hazards of the job and wear protective gear such as safety glasses, safety shoes, hard hat, etc. to
provide adequate protection.