How often should belts and hoses be replaced?
Most hose manufacturers recommend replacing hoses every four years.
V-belts should be replaced every three years or 36,000 miles. The
incidence of failure rises sharply after the fourth year of service
for hoses and third year for belts.
The lifespan of a typical serpentine belt is about five years or
50,000 miles. Serpentine belts are thinner and more flexible than
V-belts. They run cooler and last longer, but cost about twice as
much to replace.
The hard part is convincing customers to change belts and hoses as
preventative maintenance BEFORE they fail. Few people do, yet they
could save themselves a lot of unnecessary grief and expense if they
would.
Rubber hoses deteriorate with age. Tiny cracks develop in the rubber
which eventually cause hoses to split, blister or leak. Oil
contamination and atmospheric ozone can accelerate the process.
Engine vibration and motion can cause hoses to wear if they are too
short or rub against other parts. This applies to fuel, vacuum and
emission hoses as well as coolant hoses.
A visual inspection will often uncover bad hoses. Pinching hoses to
check for age cracks, brittleness or mushiness can also help locate
hoses that need to be changed.
However, neither technique will reveal all the hoses that might need
replacing because hoses wear as much from the inside out as they do
from the outside in. A hose that appears okay on the outside may
actually be on the verge of failure because of internal
deterioration.
According to research done by one hose manufacturer, internal
corrosion caused by electrochemical degradation is the primary cause
of cooling system hose failure.
The coolant acts like an electrolyte and allows a current to flow
between engine and radiator. This causes micro-cracks to form inside
the hose which eventually leads to pinhole leaks and weakening of
hose fibers.
With belts, heat and mileage are the main causes of wear. Every time
a belt passes around a pulley, it bends and flexes. This produces
heat which hardens the rubber over time. The wear process is greatly
accelerated if the belt is loose and slips.
The additional friction between belt and pulley will make a belt run
hotter. After millions of journeys around the pulleys, even the best
drive belt begins to suffer the effects of age. Rubber begins to
crack and fray and the internal cords become weak and brittle.
You cannot always determine a belt's true condition by appearances
alone. Any belt obviously cracked and frayed should be replaced.
With many of today's bandless belts, there is no outside cover to
peel loose and betray the belt's deteriorated condition.
A belt may appear to be like new on the outside, yet be on the verge
of failure because of weakened separated cords inside.
When a belt is replaced, it is important that the belt be properly
tensioned. If too loose, it will slip and wear quickly. If too
tight, it may damage internal cords as well as overload shaft
bearings on accessories it drives.
The rule of thumb about tightening a belt until there is about half
an inch of give between the two furthest pulleys is not always
accurate. A belt gauge" that measures actual tension is the only
sure way to know if a belt is tensioned properly.
Because a V-belt normally takes a set after a few minutes of
running, one set of tension specs may be provided for new belts and
another for used belts. Any V-belt that has been run for more than
15 minutes should be considered a used belt.
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