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Subaru Legacy Service Manual: General diagnostic table inspection

Subaru Legacy Service Manual / Clutch system / General diagnostic table inspection

1. CLUTCH

Symptoms

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 temporarily speeds up when the accelerator ON immediately after shifting.

High-speed driving is not possible; especially rapid acceleration is not possible and vehicle speed does not increase in proportion to the increase in engine speed.

Power drops particularly when ascending 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: General Diagnostic Table > INSPECTION

The problem is caused by insufficient disengagement 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 sticking

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 vibration 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.

4. Noisy clutch

Examine whether the noise is generated when the clutch is disengaged, engaged, or partially engaged.

(a) Broken, worn or insufficiently lubricated release bearing

Replace the release bearing.

(b) Insufficient lubrication of the pilot bearing

Replace the pilot bearing.

(c) Loose clutch disc hub

Replace the clutch disc.

(d) Loose damper spring retainer

Replace the clutch disc.

(e) Deteriorated or broken damper spring

Replace the clutch disc.

5. Clutch grabs suddenly.

When starting the vehicle with the clutch partially engaged, the clutch engages suddenly and the vehicle jumps instead of making a smooth start.

(a) Grease or oil on facing

Replace the clutch disc.

(b) Deteriorated cushioning spring

Replace the clutch disc.

(c) Worn or rusted spline of clutch disc or main shaft

Take off rust, apply grease or replace clutch disc or main shaft.

(d) Deteriorated or broken damper spring

Replace the clutch disc.

(e) Loose engine mounting

Retighten or replace mounting.

(f) Deteriorated diaphragm spring

Replace.

2. CLUTCH PEDAL

Symptoms

Corrective action

Insufficient clutch pedal free play

Adjust the free play of the pedal.

Excessively worn and damaged pedal shaft and/or bushing

Replace the bushing or shaft with a new part.

3. DIAGNOSTIC DIAGRAM OF CLUTCH DRAG

STEPCHECKYESNO

1.CHECK GEAR NOISE.

1) Start the engine.

2) While idling the engine, step on the clutch pedal and quickly shift from neutral to reverse.

Is there any abnormal noise from the transmission gear-

General Diagnostic Table > INSPECTION

Clutch is normal.

2.CHECK GEAR NOISE.

Depress the clutch pedal at idle and shift from neutral to reverse within 0.5 — 1.0 second.

Is there any abnormal noise from the transmission gear-

General Diagnostic Table > INSPECTION

Defective transmission or excessive clutch drag torque. Inspect pilot bearing, clutch disc, transmission and clutch disc hub spline.

3.CHECK GEAR NOISE.

1) Depress the clutch pedal at idle and shift from neutral to reverse within 0.5 — 1.0 second.

2) While stepping on the clutch pedal, shift from neutral to reverse, reverse to neutral several times.

Is there any abnormal noise from the transmission gear-

Inadequate clutch disengage. Inspect the clutch disc, clutch cover, clutch release, and clutch pedal free play.

Clutch and flywheel seizure. Inspect the clutch disc and the spline of the clutch disc hub.

Clutch fluid air bleeding procedure
CAUTION:Be careful not to spill the brake fluid. Brake fluid spilled on the vehicle body will harm the paint surface; wash it off with water and wipe clean quickly if spilled.NOTE:Bleed air from the o ...

Clutch disc and cover
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Other materials:

Replacement
CAUTION:If the engine oil is spilt over exhaust pipe or the under cover, wipe it off with cloth to avoid emission of smoke or causing a fire.1. Open the oil filler cap for quick draining of engine oil.2. Lift up the vehicle.3. Drain engine oil by loosening the drain plug.NOTE:Prepare the container f ...

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