Tuesday, July 1, 2008


Drive belt placed on the crankshaft pulley, the belt deliver crankshaft power to the water pump,cooling fan,alternator,power steering oil pump,air conditioner compressor and vacum pump (diesel engine only).
As the belt are made of rubber, they gradually become worn and harden because of friction with pulley,the heat originated by its friction and elasticity by the engine torque change,and it will finally crack.

Serious trouble may result such as:

  • If the power steering belt break, the steering will suddenly become extremely heavy.
  • If fan belt breaks, water pump will not operated and engine will overheat.
  • If alternator belt breaks,battery will be discharged.
  • If air conditioner belt breaks, air conditioner will not operate ( HOT).
  • If vacum pump belt breaks (diesel engines) the brake pedalwill suddenly become stiff,making it extremely hard to applay brakes.

Inspect and correct or replace as necessary every 20,000km/12 months after 1st maintenance,whichever comes first for without three way catalyst model. For model with three way catalyst every 40,000km/ 24 months.


  1. Inspect for cracks, fraying,wear or oil adhesion. If necassary, replace witht a new one.
  2. Inspect the belt deflections by pushing on the belt midway between pulleys with a force of 98N ( 10 kg.22lb ).
  3. Adjust if belt deflections is too small or too large. Specified deflection limit is shown in Service Manual.

Genuine belts are made of proper materials to form precise stucture and configuration matching each vehicle and engine type. They are of appropriate length so as to permit sufficient for tension adjusment.These characteristics are essential for a long service life.

The factory-fitted thermal-contraction belt are low-maintenance products.If the belt tension decreases, the belt starts slipping and produces heat which makes the inside cords shrink, thus recovering the tension.

Does any problem happen if belt tension is too high or too low?

Yes, you will have problem either case.

If tension is weak, belt will slip against the pulley,and power transfer will become lower.this means,in case of fan belt,cooling power will decrease and in case of alternator belt,generating power will decrease and battery charge level will decrease. This can be easily niticed as sharp squeaking noise will be generated when racing engine.

On the other hand,excessive tension leads to short life of alternator bearing,water pump bearing or crankshaft main bearing.

Belts used for a vehicle are all same?


Belts look the same,however ,length and width are slighly different.

For example,you can not use air conditioner belt in place of fan belt.

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