Mitsubishi Heavy Industries S3L, Service Manual

Page: 43 / 200

DETERMINATION OF OVERHAUL
4-3
2. Testing compression pressure
&$87,21
(a) Be sure to measure the compression pressure for
all the cylinders. It is not a good practice to mea-
sure the compression pressure for only one cylin-
der, and presume the compression for the
remaining cylinder.
(b) Also be sure to check engine speed when measur-
ing the compression pressure, as compression
pressure varies with engine speed.
(c) Measuring the compression pressure at regular in-
tervals is important to obtain correct data.
(d) When measuring the compression pressure for
cylinders one by one, do not remove other fuel
injection nozzles from their positions, except for
the one being measured.
(1)
Remove the injection nozzle from the cylinder head
where the compression pressure is to be measured.
(2)
Remove the glow plugs from all cylinders.
(3)
Attach the compression gauge adapter to the injection
nozzle mount, and connect compression gauge.
(4)
Stop the fuel supply.
(5)
Crank the engine with the starter, then read the
compression gauge indication while the engine is
running at the specified speed.
(6)
If the compression pressure is lower than the limit,
overhaul the engine.
Testing compression pressure
Item Standard Limit
Engine speed
290 min
-1 -
Compression
pressure
2.9 MPa
{30 kgf/cm²}
[421 psi]
2.6 MPa
{27 kgf/cm²}
[377 psi]
Tolerable difference
between cylinders
0.29 MPa
{3.0 kgf/cm²}
[42 psi] or less
-
Compression
gauge
Compression
gauge adapter