Toro Groundsmaster 455-D Service Manual page 46

Compression Test
Minimum cylinder compression is 20 bar (290 psi) at 200
rpm (normal cranking speed). The engine should be
o o
warm - coolant temperature of 50 C (120 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 four cylinders.
2. Insert a compression gauge adapter into the glow
plug hole.
3. Connect a high pressure compression gauge to the
adapter.
4. Disconnect the fuel stop solenoid electrical connector
or hold the fuel stop lever in the stop position to prevent
fuel delivery during the compression test. 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. If the pressure is less than 20 bar (290 psi) it will be
necessary to find the cause of low compression.
7. Repeat the test for the other three cylinders. Dif­
ference between cylinders should be no more than 5 bar
(70 psi).
8. Connect the fuel stop solenoid electrical connector.
9. Install the glow plugs.
Page 3 - 28 Rev. B
Engine Groundsmaster 455-D