Mitsubishi diesel engines, Service Manual, Page: 40 / 219

OVERHAUL TIMING
1 - 27
2. Measuring the Compression Pressure
(1)
Move the control lever to STOP position.
(2)
Remove the glow plugs from all cylinders.
Install the special tool Compression Gauge
Adapter and a compression gauge onto the
cylinder being measured.
Special tool Part number
Compression Gauge Adapter ST332270
(3) While cranking the engine with the starter, read
the compression gauge. Note the reading at
which the gauge needle stabilizes.
(4)
If the measured value is at or below the limit,
overhaul the engine.
(a) Measure all cylinders for compression
pressure. Do not measure only one
cylinder and make assumption about the
other cylinders as this will lead to a wrong
conclusion.
(b) Compression pressure varies depending
on the engine speed. Keep the specified
engine speed when measuring the
compression pressure.
Standard value Limit
Engine speed 290 min
-1
Compression
pressure
2.9 MPa
(30 kgf/cm
2
)
[421 psi]
2.6 MPa
(27 kgf/cm
2
)
[377 psi]
Tolerable
difference
between
cylinders 0.29 MPa
(3.0 kgf/cm
2
)
[42 psi]
or less
It is important to regularly check the
compression pressure so that you can tell the
difference.
・
New or overhauled engines have slightly
higher compression pressure.
・
The compression pressure settles to the
standard value as the piston rings and
valve seats fit in.
・
As wear progresses further, the
compression pressure drops.
Compression
gauge adapter
Compression
gauge
Measuring the compression pressure