Subaru 2009 IMPREZA, Service Manual

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CL-29
General Diagnostic Table
CLUTCH SYSTEM
12.General Diagnostic Table
A: INSPECTION
1. CLUTCH
Symptom Possible cause Corrective action
1. Clutch slippage.
It is hard to perceive clutch slippage in
the early stage, but pay attention to the
following symptoms.
• Engine speeds up when shifting.
• High-speed driving is not possible;
especially rapid acceleration is not possi-
ble and vehicle speed does not increase
in proportion to the increase in engine
speed.
• Power drops particularly when ascend-
ing a slope, and there is a burning smell
of the clutch plate.
• Method of testing: Park the vehicle and
fully apply the parking brake. Disengage
the clutch and shift the transmission gear
into the 1st. Gradually increase the
engine speed while gradually allowing the
clutch to engage. The clutch function is
satisfactory if the engine stalls. However,
the clutch is slipping if the vehicle does
not move forward and the engine does
not stall. (a) Oil on the clutch face Replace.
(b) Worn clutch face Replace.
(c) Deteriorated diaphragm spring Replace.
(d) Warped pressure plate or flywheel Repair or replace.
(e) Defective release bearing holder Repair or replace.
2. Clutch drags.
As a symptom of this trouble, a harsh
scratching noise occurs and control
becomes difficult when shifting gears.
The symptom becomes more apparent
when shifting into the 1st gear. However,
because most trouble of this sort is due to
a defective synchronization mechanism,
perform the following tests.
• Method of testing:<Ref. to CL-30,
DIAGNOSTIC DIAGRAM OF CLUTCH
DRAG, INSPECTION, General Diagnos-
tic Table.>
The problem is caused by insufficient dis-
engagement of the clutch if an abnormal
noise occurs during this test. (a) Worn or rusty clutch disc hub spline Replace the clutch disc.
(b) Excessive deflection of clutch disc
face Repair or replace.
(c) Crankshaft pilot needle bearing stick-
ing Replace.
(d) Cracked clutch disc face Replace.
(e) Stuck clutch disc (smeared by oil or
water) Replace.
3. Clutch chatters.
Clutch chattering is an unpleasant vibra-
tion to the whole vehicle when the vehicle
is just started with clutch partially
engaged. (a) Adhesion of oil on the clutch face Replace the clutch disc.
(b) Weak or broken damper spring Replace the clutch disc.
(c) Poor contact of the disc surface or
excessively worn disc Replace the faulty clutch disc.
(d) Warped pressure plate or flywheel Repair or replace.
(e) Loose disc rivets Replace the clutch disc.
(f) Loose engine mounting Retighten or replace mounting.
(g) Improper adjustment of the pitching
stopper Adjust.