TM 5-3895-346-14
ENGINE OVERHAUL
GENERAL DESCRIPTION
GENERAL DESCRIPTION
However, there are times when a slight amount of reworking or reconditioning may save a customer
considerable added expense. Crankshafts, cylinder liners, and other parts are in this category. For example, if
a cylinder liner is only slightly worn and within usable limits, a honing operation to remove the glaze may make
it suitable for reuse, thereby saving the expense of a new part. Exchange assemblies such as injectors, fuel
pumps, water pumps, and blowers are also desirable service items.
Various factors such as the type of operation of the engine, hours in service, and next overhaul period must be
considered when determining whether new parts are installed or used parts are reconditioned to provide
trouble-free operation.
For convenience and logical order in disassembly and assembly, the various subassemblies and other related
parts mounted on the cylinder block will be treated as separate items in the various sections of the manual.
DISASSEMBLY
Before any major disassembly, the engine must be drained of lubricating oil, coolant, and fuel. Lubricating oil
should also be drained from any transmission attached to the engine.
To perform a major overhaul or other extensive repairs, the complete engine assembly, after removal from the
engine base and drive mechanism, should be mounted on an engine overhaul stand; then the various
subassemblies should be removed from the engine. When only a few items need replacement, it is not always
necessary to mount the engine on an overhaul stand.
Parts removed from an individual engine should be kept together so they will be available for inspection and
assembly.
Those items having machined faces, which might be easily damaged by steel or concrete, should be stored on
suit- able wooden racks or blocks, or a parts dolly.
CLEANING
Before removing any of the subassemblies from the engine (but after removal of the electrical equipment), the
exterior of the engine should be thoroughly cleaned. Then, after each subassembly is removed and
disassembled, the individual parts should be cleaned. Thorough cleaning of each part is absolutely necessary
before it can be satisfactorily inspected. Various items of equipment needed for general cleaning are listed
below.
The cleaning procedure used for all ordinary cast iron parts is outlined under Clean Cylinder Block, any special
cleaning procedures will be mentioned in the text wherever required.
Steam Cleaning
A steam cleaner is a necessary item in a large shop and is most useful for removing heavy accumulations of
grease and dirt from the exterior of the engine and its subassemblies.
Solvent Tank Cleaning
A tank of sufficient size to accommodate the largest part that will require cleaning (usually the cylinder block)
should be provided and provisions made for heating the cleaning solution to 180-200 (82-90 ).
F
C
Fill the tank with a commercial heavy-duty solvent which is heated to the above temperature. Lower large parts
directly into the tank with a hoist. Place small parts in a wire mesh basket and lower them into the tank.
Immerse the parts long enough to loosen all the grease and dirt.
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