There was a
time when rubber belts and hoses were maintenance items that had to be
replaced every five or six years, depending on their condition.
original equipment belts and hoses on today’s late model vehicles are
mostly made of EPDM (ethylene propylene diene monomer), a synthetic
rubber that is far more durable, heat-resistant and wear-resistant than
Neoprene. This means serpentine belts and hoses made of EPDM may last
up to 100,000 miles or more before they have to be replaced. But that
doesn’t mean they will last forever.
A serpentine belt that’s
aging or slipping may develop a hard glazed surface that makes the belt
noisy. Aerosol belt treatments may quiet the noise for awhile, but
sooner or later your customer will have to replace the belt.
appearance of surface cracks in the rubber is another clue that a belt
is reaching the end of the road and should be replaced the sooner the
better because a belt failure will result in a breakdown (loss of
engine cooling, A/C cooling, charging output and power steering
Belt noise and/or premature wear is often the result of a
bad automatic tensioner. Customers should be advised to check their
belt tensioner if a serpentine belt is making noise, slipping or
fluttering when the engine is revved. High mileage tensioners often
have weak springs and can stick if there is corrosion in the pivot
bearing. A special tool is often needed to rotate the tensioner so the
belt can be replaced.
Can’t find the automatic belt tensioner?
Some late model engines don’t have one. Instead, they use a new type of
“Stretch Fit” serpentine belt. Such belts have special polyamide
tension cords inside that allow the belt to stretch slightly (like a
rubber band), but in a controlled way so belt tension is maintained
without the need of a tensioner. Ordinary serpentine belts do not
stretch, and must use a tensioner or have some type of adjustments on
the belt-driven accessories.
Though ordinary replacement
serpentine belts must be the exact same length as the original to fit
properly, Stretch Fit belts are actually slightly shorter than the
original belt. Installation requires routing the belt around all of the
pulleys, then stretching it over the last pulley with a special tool.
for the new stretch Fit belts include 2004 and up Mazda MPV and Tribute
3.0L, 2005 and up Ford Escape 3.0L, 2006 & up Ford Fusion 3.0L,
2008 Ford Taurus 3.5L, 2007 and newer Chrysler Sebring and Dodge
Stratus 2.7L, 2007 and up Dodge Nitro 4.0L, 2008 and up Chevy Silverado
and GMC Sierra trucks, and 2008 and 2009 Hummer H3.
Stretch Fit belts are NOT designed to replace ordinary serpentine belts
on older vehicles. They must only be used on newer vehicles that are
designed for them. Likewise, an ordinary serpentine belt should not
used in an application that requires a Stretch Fit belt. Attempting to
stretch an ordinary serpentine belt over a pulley can damage the cords
inside it and cause the belt to fail.
Something else that’s new is
the use of overrunning alternator decouplers (OAD) on a growing number
of late model vehicles, including Chevrolet Corvette, Camaro and HHR,
Buick Lucerne, Cadillac CTS and Escalade, Volvo XC60 and XC90, and
various Lexus, Scion and Toyota models.
decouplers (also referred to as isolating decoupler pulleys, or IDP)
help enhance engine efficiency and reduce noise, vibration and
harshness. Using any other type of replacement pulley on an alternator,
such as a one-way clutch, isolating pulley or solid pulley, on an
application that came originally equipped with an OAD pulley can lead
to customer complaints about noise and vibration, as well as premature
As for the hoses in the cooling system, coolant
leaks are bad news because they can result in loss of coolant and rapid
engine overheating. If an engine gets too hot, it may ruin the
thermostat, damage the head gasket or cause the pistons to scuff. To
prevent coolant leaks and breakdowns, hoses should be inspected
periodically and replaced if showing signs of aging such as surface
cracks, loss of pliability, unusual hardness, bulging or leaks.