General Diagnostic - Subaru 2004 Impreza Service Manual

25.General Diagnostic

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
malfunction of the gear shift system and
the other is malfunction of the transmis-
sion. However, if the operation is heavy
and engagement of the gears is difficult,
defective clutch disengagement may also
be responsible. Check whether the clutch
is correctly functioning, before checking
the gear shift system and transmission.
2. Gear slips out.
• Gear slips out when coasting on rough
road.
• Gear slips out during acceleration.
3. Unusual noise comes from transmis-
sion.
NOTE:
If an unusual noise is heard when the ve-
hicle is parked with its engine idling and if
the noise ceases when the clutch is disen-
gaged, it may be considered that the
noise comes from the transmission.
General Diagnostic
Possible cause
(a) Worn, damaged or burred chamfer of
internal spline of sleeve and reverse
driven gear
(b) Worn, damaged or burred chamfer of
spline of gears
(c) Worn or scratched bushings
(d) Incorrect contact between synchro-
nizer ring and gear cone or wear
(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
(responsible for 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 tooth sur-
faces, merely a high roaring noise will oc-
cur at high speeds, but if any part is
broken, rhythmical knocking sound will be
heard even at low speeds.
5MT-117
MANUAL TRANSMISSION AND DIFFERENTIAL
Replace.
Replace.
Replace.
Correct or replace.
Adjust.
Tighten or replace.
Replace.
Replace.
Replace.
Replace.
Replace.
Replace.
Replace.
Replace.
Replace.
Lubricate or replace with specified oil.
Replace.
Remedy