Accessory Drive; Belt Tensioners; Drive Belts; Visual Diagnosis - Mercedes-Benz 2005 Sprinter Service Manual

VA

BELT TENSIONERS

DESCRIPTION . . . . . . . . . . . . . . . . . . . . . . . . . . 5
OPERATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

DRIVE BELTS

DIAGNOSIS AND TESTING - ACCESSORY
DRIVE BELT . . . . . . . . . . . . . . . . . . . . . . . . . . 5
BELT TENSIONERS
DESCRIPTION
CAUTION: Do not attempt to check belt tension with
a belt tension gauge on vehicles equipped with an
automatic belt tensioner.
Drive belts on all engines are equipped with a
spring loaded automatic belt tensioner. This ten-
sioner maintains constant belt tension at all times
and requires no maintenance or adjustment.
OPERATION
WARNING: THE AUTOMATIC BELT TENSIONER
ASSEMBLY IS SPRING LOADED. DO NOT ATTEMPT
TO DISASSEMBLE THE TENSIONER ASSEMBLY.
The automatic belt tensioner maintains correct belt
tension using a coiled spring within the tensioner
housing. The spring applies pressure to the tensioner
arm pressing the arm into the belt, tensioning the
belt.
If a new belt is being installed, the arrow must be
within approximately 3 mm (1/8 in.) of indexing
mark. Belt is considered new if it has been used 15
minutes or less. If this specification cannot be met,
check for:
• The wrong belt being installed (incorrect length/
width)
• Worn bearings on an engine accessory (A/C com-
pressor, power steering pump, water pump, idler pul-
ley or generator)
• A pulley on an engine accessory being loose
• Misalignment of an engine accessory
• Belt incorrectly routed.

ACCESSORY DRIVE

TABLE OF CONTENTS
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DRIVE BELTS
DIAGNOSIS AND TESTING - ACCESSORY
DRIVE BELT

VISUAL DIAGNOSIS

small cracks that run across the ribbed surface of the
belt from rib to rib (Fig. 1), are considered normal.
These are not a reason to replace the belt. However,
cracks running along a rib (not across) are not nor-
mal. Any belt with cracks running along a rib must
be replaced (Fig. 1). Also replace the belt if it has
excessive wear, frayed cords or severe glazing.
1 - NORMAL CRACKS BELT OK
2 - NOT NORMAL CRACKS REPLACE BELT
REMOVAL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
INSTALLATION . . . . . . . . . . . . . . . . . . . . . . . . . . 8
When diagnosing serpentine accessory drive belts,
Fig. 1 Belt Wear Patterns
ACCESSORY DRIVE 7 - 5
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