Crankcase - Toro GTS 120 Service Manual

2. Pull the starter rope rapidly several times
until the compression reading on the gauge
stabilizes.
3. If thecompression reading is below 6.5 kps-cm2
(92 psi), cylinder, piston or ring damage should
be suspected. A new engine should have 8.4
kps-cm2
(1
20 psi) 1 0.5 kps-cm2
(1
50 psi).
An engine with low compression must be dis-
assembled and inspected for damage of the
internal components. (See Disassembly Instruc-
tions.) Check all components to the specifica-
tions listed in the Service Data Section of this
manual. Replace all parts which fall outside of
these specifications. The engine contains a cast
iron cylinder liner, which is not replaceable.
Special factory processes are required to install
this liner.
CRANKCASE
The engine relies on a tightly sealed crankcase
in order to function properly. The downward
movement of the piston causes the crankcase to
be pressurized. This pressure is required to
expell the exhaust gases from the combustion
chamber and to supply a fresh fuel mixture for
the compression stroke. The upward movement
of the piston on the compression stroke creates
a vacuum to draw fresh fuel into the crankcase.
In both instances a tightly sealed crankcase is
the key to efficient performance. The most likely
places of leakage are at the governor shaft seal,
crankshaft seals and at the seam of the crank-
case halves. The simplest means of detecting a
crankcase leak is to check for wet, oily deposits
around the seal areas.
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