Compression Test
Normal cylinder compression is 28 kg/cm
2
(398 psi) at
280 rpm (normal cranking speed). The engine should
be warm - coolant temperature of 50
o
C (120
o
F).
IMPORTANT: DO NOT put oil into the combustion
chamber before performing a compression test.
Damage may result because of “hydraulic” forces
acting upon the piston and connecting rod.
1. Remove the glow plug lead wires and glow
plugs from
all three cylinders.
2. Insert the compression gauge adapter into the glow
plug hole. (See the Special Tools section of this chapter.)
3. Connect the high pressure compression gauge to the
adapter (Fig. 16).
4. Disconnect the fuel stop solenoid electrical connector
to prevent fuel delivery during the compression test
(Fig. 17). This will prevent wash-down of the cylinders
and inaccurate readings.
5. Crank the engine with the starter motor until
you get
a stable gauge reading.
6. Normal compression is 28 - 32 kg/cm
2
(398 - 455 psi).
If the pressure is less than 25 kg/cm
2
(356 psi) it will be
necessary to find the cause of low compression. (See
Engine Fails to Start - Low Compression in the Trou-
bleshooting section of this chapter.)
7. Repeat the test for the other two cylinder
s. Difference
between cylinders should be no more than 2.5 kg/cm
2
(36 psi).
8. Connect the fuel stop solenoid electrical connector.
Figure 16
1
Figure 17
1. Fuel stop (ETR) solenoid electrical connector
Reelmaster
®
223-D/5100-D Page 3 - 19 Testing
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