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.
The 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.
The 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
(i.e., loss of engine cooling).
Belt noise and/or premature wear is often the result of a bad automatic
tensioner. Intallers should be advised to check the 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.
Applications 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.
The New 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.
Overrunning alternator 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 belt failure.
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.
