Checking Crankcase - APRILIA M192M Workshop Manual

Engines M192M / M191M / M245M / M234M / M282M / M281M
3.5.4.

CHECKING CRANKCASE

•
Before checking the casing, thoroughly clean all sur-
faces and lubrication ducts.
•
On the transmission-side casing, pay particular atten-
tion to the oil pump ducts and seat, by-pass duct, main
bearings and cooling jet (1).
NOTE Jet is fed through main bearings. Piston crown cooling
is improved if this part is working properly. In case of ob-
struction, some hidden problems (piston temperature in-
crease) will arise. If this part is not installed or if it leaks,
main bearings and con-rod lubrication pressure could be
abruptly reduced. As already described under section lubri-
cation, the by-pass seat does not have to be worn in order
not to affect piston correct sealing for lubrication pressure
adjustment.
• On the flywheel pay particular attention to the side
main bearings lubrication ducts, oil delivery to head
duct and oil seal drain duct.
NOTE Oil delivery to head drain duct is equipped with a
shutter jet: this allows a head "low-pressure" lubrication in
order to keep the sump oil temperature low. In case jet is
blocked, head and timing system mechanisms lubrication will
be impaired. In case jet is not present, main bearings and
con-rod bearings lubrication pressure will be reduced.
•
Check that surfaces are neither dented or out of shape,
carefully inspect casing-cylinder and casing mating
surfaces.
• In the event of a fault of the casing jointing gasket or
the surfaces pressurized oil could leak and lower the
main bearings and con-rod bearings lubrication pres-
sure.
• Check crankshaft axial play holding surfaces for wear.
For dimensional check, follow the instructions given to
check axial play and to take crankshaft readings.
ENGINE
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