217 

 

No. 160 Clutch slipping   

Malfunction Causes

Solution 

(1) Free stroke of clutch pedal too small or zero, 
diaphragm spring force fully or partially acting on 
operation mechanism, making driven disk 
unable to well pressed with flywheel and clutch 
plate; 

Adjust free stroke of clutch; 

(2) Driven disk with oil sludge, causing reduced 
its surface friction force or its hardened;   

Remove oil sludge and eliminate oil 
leaking; or replace driven disk; 

(3) Working face of driven friction disk, clutch 
plate and flywheel severely worn, thickness 
reduced;   

Replace driven disk;   

(4) Spring annealing, diaphragm spring fatigue 
or broken;   

Replace clutch plate assembly; 

(5) Fixed screws for clutch plate and flywheel 
loosening;   

Fasten bolt;   

When releasing 
clutch, the vehicle 
could not be started; 
during accelerating, 
rotating speed of 
engine rises, and 
vehicle speed not 
rising accordingly; 
when going against 
long slope, clutch 
smoking with pasting 
smell. When pulling 
on parking brake for 
startup test, engine 
shall stall; if not, it 
indicates that the 
clutch slips. 

(6) Space between release bearing sleeve and 
its guide pipe with oil sludge, dust or blocked, 
unable to return; 

Clean guide pipe; 

Diagnosis program for clutch driving, slipping 

 

 

 

 
 

 

 

218 

 

No. 161 Heavy clutch   

Malfunction Causes 

Solution 

 

1. Clutch drive mechanism deformed, 
jammed;  

Check drive mechanism is deformed or jammed; correct and 
repair if so; 

2. Clutch tie-line jammed;   

Clean or replace clutch tie-line;   

3. Clutch master cylinder damaged, 
blocked;  

Check clutch master cylinder is damaged, blocked; replace it 
if so;   

4. Clutch wheel cylinder damaged, blocked; 

Check clutch wheel cylinder is damaged, blocked; replace it if 
so; 

Feel heavy and 
hard when 
stepping down 
clutch pedal   

4. Foreign substances or rust at pivoting of 
diaphragm spring of clutch plate; 

Check any foreign substances or rusts at pivot; clean them or 
lubricate rusts if so;   

 

Heavy clutch 

Correct and repair 

Clutch drive mechanism deformed, jammed 

Foreign substances or rust at pivoting of diaphragm spring of clutch plate 

Clutch master cylinder damaged, blocked 

Clutch wheel cylinder damaged, blocked 

Clean or lubricate 

Clean or replace 

Clutch tie-line jammed or fouling 

Replace 

Replace 

Normal 

Unusual 

Normal 

Normal 

Normal 

Unusual 

Damaged 

Damaged 

Unusual

 
 

 

 

219 

 

No. 162 Not fully separated   

Malfunction Causes 

Solution 

(1) Free stroke of clutch too large, diaphragm spring force fully or partially 
acting on operation mechanism when stepping down the pedal, making 
diaphragm spring not fully compressed, and driven disk unable to well 
separated with flywheel and clutch plate; 

Adjust it; 

(2) Clutch plate diaphragm uneven, not within the same plane;   

Replace clutch plate;   

(3) Driven disk incorrectly installed, causing friction between driven disk 
and flywheel;   

Reassemble;  

(4) Driven disk warped, deformed, causing friction between driven disk 
and flywheel or clutch plate; 

Correct driven disk;   

(5) Clutch driven disk too thick;   

replace driven disk of standard 
thickness;  

Malfunction: when 
the engine is 
operating at idling 
speed, step on 
clutch pedal, 
impact sound of 
gear occurs when 
put into gear at 
original position, 
and hard to put into 
gear; if severe, 
engine will stall 

(6) Spline hub of driven disk not flexibly moved at one shaft (output shaft) 
of transmission, causing friction between driven disk and flywheel or 
clutch plate, and making clutch not fully separated;   

Replace driven disk;   

 

 
 

 

 

220 

  Diagnosis program for not fully separated clutch