Subaru 2009 IMPREZA Service Manual page 2152

MANUAL TRANSMISSION AND DIFFERENTIAL
20.General Diagnostic Table
A: INSPECTION
1. MANUAL TRANSMISSION
Symptom
1. Gears are difficult to intermesh.
NOTE:
The cause for difficulty in shifting gears
can be classified into two kinds: One is a
defective gear shift system and the other
is defective transmission. However, if the
operation is heavy and engagement of the
gears is difficult, a defective clutch disen-
gagement may also be responsible.
Check whether the clutch is correctly
functioning, before checking the gear shift
system and transmission.
2. Gear slip-out
• Gear slips out when coasting on rough
road.
• Gear slips out during acceleration.
3. Noise emitted from transmission
NOTE:
If a noise is heard when the vehicle is
parked with its engine idling and if a noise
ceases when the clutch is disengaged, it
may be considered that the noise is com-
ing from the transmission.
General Diagnostic Table
Possible cause
(a) Worn, damaged or burred chamfer at
internal spline of the sleeve and reverse
driven gear
(b) Worn, damaged or burred chamfer of
gear spline
(c) Worn or scratched bushings
(d) Incorrect contact or wear between
synchronizer ring and gear cone
(a) Defective pitching stopper adjustment
(b) Loose engine mounting bolts
(c) Worn fork shifter, broken shifter fork
rail spring
(d) Worn or damaged ball bearing
(e) Excessive clearance between splines
of synchronizer hub and synchronizer
sleeve
(f) Worn tooth step of synchronizer hub
(caused by slip-out of 3rd gear)
(g) Worn 1st driven gear and driven shaft
(h) Worn 2nd driven gear and bushing
(i) Worn 3rd drive gear and needle bear-
ing
(j) Worn 4th drive gear and needle bear-
ing
(k) Worn reverse idler gear and bushing
(a) Insufficient or improper lubrication
(b) Worn or damaged gears and bearings
NOTE:
If the trouble is only wear of the gear teeth
surfaces, only a high whirring noise will
occur at high speeds, but if any part is bro-
ken, rhythmical clicking sounds will be
heard even at low speeds.
5MT-80
Corrective action
Replace.
Replace.
Replace.
Correct or replace.
Adjust.
Tighten or replace.
Replace.
Replace.
Replace.
Replace.
Replace.
Replace.
Replace.
Replace.
Replace.
Lubricate with specified oil or replace.
Replace.