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Timing Belt
FAQ's
ANSWER:
It is good preventive maintenance and
recommended by vehicle manufacturers. Engines used to have
timing chains to keep the cam and crankshafts in sync with each
other. As belt technology and materials improved, belts replaced
the chains.
A rubber timing belt has fiberglass or
"Kevlar" reinforcing cords that keep it from stretching or
breaking. The belt wears out in use as it is constantly moving
around three or more pulleys. As the belt ages small cracks
develop in the rubber as it hardens from the constant movement
and heat from the engine. The heat and movement also weaken the
reinforcing cords in the belt and it starts to stretch. Sooner
or later the belt fails.
Some belts will last the life of the
engine and some break even before 60,000 miles. Some engines
lack valve to piston clearance, these are referred to as
interference engines. When the timing belt breaks the camshaft
or camshafts stop almost instantly while the pistons continue to
move. If the valves ( the camshaft opens and closes the valves )
stop in an open position and the pistons are still moving upward
they will hit the valves, this could bend or break them both.
The engine could have to be replaced if that happens. Since no
one can predict when the timing belt will break it's better to
follow the vehicle manufacturer's recommended service schedule.
