249 

 

No. 180 Braking intermittently stiffening   

Malfunction  

Causes 

Solution  

Vacuum tube of vacuum booster with cracks, or air 
leakage 

Check vacuum tube of vacuum booster is with cracks, 
or air leakage; if so, replace it;   

Non-return valve of booster obstructed or blocked 

Check non-return valve of booster is obstructed or 
blocked; if so, clean or replace it;   

Vacuum booster damaged   

Check vacuum booster is damaged; if so, replace it;   

Machinery parts of brake pump blocked   

Check machinery parts of brake pump are blocked; if 
so, repair;   

When stepping on 
brake pedal, 
sometimes normal, 
sometimes 
stiffening  

Brake pipe obstructed   

Check brake pipe is obstructed; if so, unclog it.   

 

Braking sideslipping, swerving 

Replace 

Check tire is worn smoothly 

Check tire of the same axle is consistent 

Adjust or 
replace

Adjust 

Check tire pressure is too low or too high 

Check air is in the pipeline 

Check brake shoe, brake disk are with oil sludge 

Clean 

Empty the air 

Abnormal 

Normal 

Abnormal 

Abnormal 

Abnormal 

Abnormal 

Normal 

Normal 

Normal 

 
 

 

 

250 

 

Braking intermittently stiffening 

Replace 

Check vacuum tube of vacuum booster is with 
cracks, or air leakage 

Check non-return valve of booster is obstructed or 
blocked 

Clean or replace 

Replace 

Check vacuum booster is damaged 

Check machinery parts of brake pump are 
blocked 

Check brake pipe is obstructed 

Unclog the pipe 

Repair 

Abnormal 

Normal 

Abnormal 

Abnormal 

Abnormal 

Abnormal 

Normal 

Normal 

Normal 

 
 

 

 

251 

 

No. 181 Braking ineffective   

Malfunction Causes 

Solution 

(1) Master cylinder, wheel cylinder, pipe or pipe 
joint with oil leakage;   

Eliminate oil leaking or fasten joint screws   

(2) Master cylinder liquid chamber (tank) with 
insufficient oil or without oil;   

Add brake liquid   

(3) Brake liquid deteriorates (thinning down or 
thickening) or fouling within inner pipe wall too 
thick;  

Replace brake liquid or clean brake pipe   

(4) Air inside the brake liquid;   

Empty the air   

(5) Master cylinder leather cup, piston or cylinder 
severely worn;   

Replace leather cup piston or replace brake master 
cylinder  

(6) Wheel cylinder leather cup, piston or cylinder 
severely worn; 

Replace brake wheel cylinder   

(7) Oil inlet, compensation hole of master cylinder 
or vent hole of liquid chamber (tank) obstructed; 

Clear obstructed substances 

(8) Delivery valve, spill valve of master cylinder or 
pretightening force of piston release spring too 
small;  

Replace master cylinder   

(9) Through hole at front end of master cylinder 
piston obstructed or leather cup sticking, bloating; 

Replace master cylinder 

(10) Leather cup of wheel cylinder sticking, 
bloating;  

Replace wheel cylinder   

(11) Supercharger or booster with poor efficiency 
or ineffective;   

Replace supercharger   

(12) Oil pipe collapsed or hole inside the hose 
obstructed;  

Unclog the pipe   

(13) Brake pedal with too large free stroke;   

Adjust free stroke   

(14) Friction disk of brake shoe and brake drum 
(disk) not favorably closed or brake clearance 
incorrectly adjusted;   

Replace brake disk and brake drum or adjust clearance 

(15)    Friction disk of brake shoe with poor quality, 
or hardened surface, scorching, oil sludge or 
exposed rivet head during uses,   

Replace friction disk of brake shoe   

While braking, the 
driver feels 
deceleration 
insufficient; while 
emergency 
braking, braking 
distance too long.   
 

(16) Brake drum severely worn or deformed while 
braking;  

Replace friction disk and brake drum   

 

 
 

 

 

252 

 

Diagnosis flowchart of ineffective braking