Compression Pressure - Measure - Mitsubishi S12A2 Service Manual

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Chapter 4 OVERHAUL INSTRUCTIONS

2. Compression Pressure - Measure

(a) Be sure to measure the compression pressure of
all cylinders. It is not a clever way to measure
the compression pressure of only two or three
cylinders, and assume the compression pres-
sure of all other cylinders. Cylinders are all inde-
pendent.
(b) Also be sure to check the engine speed when
measuring the compression pressure, as the
compression pressure varies depending on the
engine speed.
(c) It is important to measure the compression pres-
sure at regular intervals, and know the change of
the pressure.
(1) Remove the injection nozzle from the cylinder head
where the compression pressure is to be measured.
(2) Attach the compression gauge adapter to the fuel injec-
tion nozzle hole and connect the compression gauge.
(3) Place the fuel injection pump rack at the no-injection
position (rack "0" position), and crank the engine with
the starter.
Read the engine speed and compression pressure while
the engine is running at a stable speed.
Note: Ensure the battery being fully charged when cranking
the engine with the starter.
If the battery voltage is low, the proper compression
pressure can not be measured because of a low crank-
ing speed.
(4) If the measured value exceeds the limit, overhaul the
engine.
Item
Standard value
2.35 MPa
Compres-
sion pres-
{24 kgf/cm
2
} or
{300 kgf/cm
sure
more
4-4
Basic
Limit value
Rotation speed
1.86 MPa
2
}
120 to 200 min
-1
[4267 psi]
Compression gauge
P/N:33A91-01700
Gauge adapter
P/N:36291-02200
Compression Pressure - Measure

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