Testing Compression Pressure - Mitsubishi S6S-Y3T61HF Service Manual

2. Testing compression pressure

CAUTION
(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 cylinders.
(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) The compression pressure will be slightly higher in
a new or overhauled engine due to new piston
rings, valve seats, etc. Pressure will drop gradually
by the wear of these parts.
(e) Turn off the solenoid valve to stop fuel injection.
(1) Remove the glow plug from the cylinder head where
the compression pressure is to be measured.
(2) Attach the compression gauge adapter to the glow plug
mount and connect compression gauge.
(3) Crank the engine with the starter, then read the
compression gauge indication while the engine is
running at the specified speed.
(4) If the compression pressure is lower than the limit,
overhaul the engine.
Item
Compression pressure
Engine speed
Oil and water tempera-
tures
Standard Limit
3.2 MPa 2.8 MPa
{33 kgf/cm²} {29 kgf/cm²}
[469 psi] [412 psi]
or more or less
-1
-
300 min
20 to 30°C
-
[68 to 86°F]
DETERMINATION OF OVERHAUL
Compression
Gauge adapter
gauge
P/N:30691-21100
P/N:33391-02100
Testing compression pressure
4-3