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Drive System

Dayco Timing Belts

 

Dayco is recognized by the automotive industry as a world leader in the manufacture of timing belts. Dayco's patented, self-lubrication fabric provides exceptional resistance to abrasion, resulting in extended pulley and belt life. The molded cog design runs quieter and is more economical than chain drives. Premium, high modulus glass fiber non-stretch cord delivers precise length stability to keep the engine running smoothly over the life of the belt. The belt's com- pounding and tooth config- urations are designed for specific applications, ranging from normal service to high performance, high temperature engines where HSN compound is used.

It is estimated that nearly one-third or approximately 70 million vehicles currently on the road in the US utilize a timing belt. Simply put, the timing belt transfers the rotation of the crankshaft to the camshaft(s). The rotating camshaft activates the valves which provide air and fuel to the cylinders and expel combustion gasses to the exhaust system. Valves and pistons are constantly moving up and down at very high speeds.

If a timing belt fails on a con- ventional engine, the transfer of rotation from the crankshaft to the camshaft will cease. The engine will stop and the mo- torist will be stranded. Valves and pistons do not come in contact and there is little likeli- hood of severe engine damage.

A timing belt failure on vehicles equipped with interference engines, however, presents a somewhat different scenario. This type of engine does not allow for clearance between a valve at its lowest point and a piston at its highest point. The critical link to ensure that these components do not collide is the timing belt. If an interference engine's timing belt fails, not only will the motorist be stranded, but additional damage to valves, pistons, cylinder head and cylinder walls can occur which can greatly escalate the cost of repair. It is essential to remember that when changing the timing belt, the timing belt system tensioner and pulleys must be ex- amined to determine if they exhibit signs of wear or damage. If so, these com- ponents should immediately be replaced.

 

TROUBLE SHOOTING TIMING BELT FAILURES

TENSILE (CORD) FAILURE: INSPECT FOR:

  • Belt crimped
  • Foreign body in drive
  • Excessive Tension
  • Moisture or antifreeze getting on belt and invading to the cord.

TIMING BELT TEETH SHEARED: INSPECT FOR:

  • Seized drive components
  • Improper tension
  • Misalignment

WORN TIMING BELT TEETH: INSPECT FOR:

  • Worn sprocket(s)
  • Improper tension

WORN LANDS BETWEEN TIMING BELT TEETH: INSPECT FOR:

  • Belt crimped
  • Foreign body in drive
  • Excessive tension
  • Moisture or antifreeze getting on belt and invading to the cord.

WORN AND CRACKED TIMING BELT BACK: INSPECT FOR:

  • High internal engine temperatures
  • Extremely low ambient temperature
  • Nicked or worn pulley(s)
  • Excessive tension
  • Excessive mileage

TIMING BELT EDGE WEAR: INSPECT FOR:

  • Damage to pulley(s) flange
  • Improper component alignment
  • Nicked or worn pulley(s)
  • Foreign body in drive system

CONTAMINATION: INSPECT FOR:

  • Timing belt cover or seal damage or improper installation
  • Water, gasoline or oil line leaks
  • Rubber deposits from wobbling belts or misalignment

NOISY TIMING BELT: INSPECT FOR:

  • Timing belt cover or seal damage or improper installation
  • Water, gasoline, or oil line leaks
  • Rubber deposits from wobbling belts or misalignment

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