Chapter 5 Overhauling Instructions; General Instructions - Mitsubishi 4DQ50 Service Manual

CHAPTER 5 OVERHAULING INSTRUCTIONS
1. GENERAL INSTRUCTIONS
1) At present we cannot say when your Model 40050 Engine should be put to a
thorough overhauling, for it presupposes under what conditions the engine will be
sued, but can mention as general hints the following cases where an overhauling is
required.
a) When, engine parts having been uniformly fatigued (or worn) down from long
use, involving a drop of output, it is judged better to overhaul it.
b) When an increase of blow-by out of crankcase has caused a notable drop of
engine output.
c) When oil consumption has increased.
d) When, with nothing wrong with oil system, a remarkable drop of oil pressure is
noticed, which is judged ascribable to the wear of metals, etc.
e) When water leaks into oil.
f) When such a serious trouble has happened inside the engine that cannot be
remedied by usual services or permits the replacement of broken or affected
assemblies.
2) In taking apart the main parts such as pistons, connecting rod, valves and metals,
arrange then or put numbers on them in an appropriate way to place them later
where they were. Remember particularly that caps on connecting rod and main
bearings, being machined in pairs with respective bodies, cannot be replaced
separately.
3) When the engine overhauled, make every service specified in "Retular Checkup
and Service Table".
4) After a thorough overhauling, practice an adequate running-in and performance
test on bench, coupling it with a dynamometer, so as to adjust it perfectly for
actual operation, for example, on the vehicle.
For fuel injection pump and governor, they must also be tested, when
overhauled, individually on a fuel injection pump tester in order to make necessary
adjustments. New units supplied in an integral assembly, "injection pump general
ass'y", can be readily put in service, as already adjust thoroughly. For informations
about the engine bench test and individual adjustment of injection pump and
governor, ask your dealer or service shop.
5) Reference to "Parts Catalogue" will greatly help you in knocking down and
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