Compression Test - Toro Groundsmaster 300 Series Service Manual

Compression Test (Fig. 17)
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Normal cylinder compression is 32 kg/cm (455 psi) at
280 rpm (normal cranking speed). The engine should
o o
be 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 three cylinders.
2. Insert the compression gauge adapter into the glow
plug hole. (See the Special Tools section of this
chapter.)
Figure 17
3. Connect the high pressure compression gauge to the
adapter.
4. Hold fuel shut off lever in closed position to prevent
fuel delivery during compression test. This will prevent
wash-down of cylinders and inaccurate readings.
5. Crank the engine with the starter motor until you get
a stable gauge reading.
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6. If the pressure is less than 26 kg/cm (370 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 cylinders. Difference
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between cylinders should be no more than 2.5 kg/cm
(36 psi).
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Groundsmaster 300 Series Page 4 - 19 Testing