Service Manual

Preparation for Engine Repair
1. Before cleaning and disassembly, carefully check for engine oil to disassembled parts, as necessary to pre-
problems that cannot be found after the engine has vent rust.
been cleaned or disassembled (e.g. oil leaks from
cracked components, gaskets or loose fittings, dam- 5. Keep the work area clean; dirt causes engine failures.
aged air cleaner or breather hoses that could cause
cylinder wear, etc.). Make a note of any problems that 6. Be very careful when working on fuel system compo-
you find. nents. Cover the work area with clean paper. Store
components of the nozzles or injector pump in clean fuel
2. Clean or wash the engine exterior thoroughly before oil. Do not allow components to strike each other or
disassembly. other objects. Wet hands with clean diesel fuel before
handling these parts.
IMPORTANT: Do not spray water on a hot engine.
Injection pump seizure or other failures could Engine Compression
result.
The time interval to overhaul the engine can most
3. Do not disassemble or remove parts that do not accurately be determined by regular and systematic
require disassembly. cylinder compression measurement. (See Compres-
sion Test in the Testing section of this chapter.)
4. Disassemble the engine in proper order, arranging
the parts the disassembled parts neatly. Apply clean
Liquid Cooled
Diesel Engine
Cylinder and Cylinder Block Overhaul
Before removing any parts, disassembly or overhaul of
the Mitsubishi engine, it is very important to understand
the nature and probable cause of the problem that made
an overhaul necessary.
When the engine trouble is caused by worn cylinders,
rin
gs or valves, one or more of the following symptoms
will occur:
1. Low engine power, and a decrease in compression
pressure.
2. Increased fuel consumption.
3. Increased lubricating oil consumption.
4. Poor engine starting.
5. Loud noises in the engine.
It is important to find the cause of the engine failure
be
fore beginning repair. Symptoms 2 and 3 in the above
list can be a result of excessive fuel injection, improper
in
jection timing, or nozzle and injection pump wear. Poor
starting may be a result of electrical problems. Noises
may be associated with a mechanical part outside the
engine. Excess fuel or oil consumption may be the result
of leaks. (See the Troubleshooting section of this
chapter.)
Another indicator of the need for an overhaul is oil
con
sumption. Make sure the engine does not leak oil.
when the oil consumption between the oil change main-
tenance interval is approximately 1-1/2 times normal
(150%), engine overhaul should be considered.
With a good knowledge of how the engine operates,
ac
cess to maintenance and compression test records,
and information in the Troubleshooting section of this
chapter, unnecessary disassembly and inspection can
be eliminated.
Workman 3300-D/4300-D
P
age 4 - 31 Liquid Cooled Diesel Engine