Correct drive belt tension is required to ensure opti-
mum performance of the belt driven engine accesso-
ries. If specified tension is not maintained, belt
slippage may cause; engine overheating, lack of
power steering assist, loss of air conditioning capacity,
reduced generator output rate, and greatly reduced
belt life.

It is not necessary to adjust belt tension on the 3/7L
and 4.7L engines. These engines are equipped with
an automatic belt tensioner (1). The tensioner main-
tains correct belt tension at all times. Due to use of
this belt tensioner, do not attempt to use a belt tension
gauge on these engines.

OPERATION

The automatic belt tensioner maintains belt tension by
using internal spring pressure, a pivoting arm and pul-
ley to press against the drive belt.

ACCESSORY DRIVE

7 - 17

REMOVAL

3.7L/4.7L ENGINE

On 4.7L engines, the tensioner (3) is equipped with
an indexing tang on back of tensioner and an
indexing stop on tensioner housing. If a new belt
is being installed, tang must be within approxi-
mately 24 mm (.94 inches) of indexing stop. Belt is
considered new if it has been used 15 minutes or
less.

If the above specification cannot be met, check for:

•

The wrong belt being installed (incorrect length/
width)

•

Worn bearings on an engine accessory (A/C
compressor, power steering pump, water pump,
idler pulley or generator)

•

A pulley on an engine accessory being loose

•

Misalignment of an engine accessory

•

Belt incorrectly routed.

NOTE: A used belt should be replaced if tensioner
indexing arrow has moved to the minmum tension
indicator. Tensioner travel stops at this point.

1. Remove accessory drive belt (Refer to 7 - COOL-

ING/ACCESSORY DRIVE/DRIVE BELTS - REMOVAL).

2. Remove tensioner assembly from mounting bracket (1).

WARNING: BECAUSE OF HIGH SPRING PRESSURE, DO NOT ATTEMPT TO DISASSEMBLE AUTOMATIC
TENSIONER. UNIT IS SERVICED AS AN ASSEMBLY EXCEPT FOR PULLEY ON TENSIONER.

3. Remove pulley bolt. Remove pulley from tensioner.

7 - 18

ACCESSORY DRIVE

INSTALLATION

3.7L/4.7L ENGINE

1. Install pulley and pulley bolt to tensioner. Tighten

bolt to 61 N·m (45 ft. lbs.) torque.

2. An indexing slot is located on back of tensioner.

Align this slot to the head of the bolt on the front
cover. Install the mounting bolt. Tighten bolt to 41
N·m (30 ft. lbs.).

3. Install accessory drive belt (Refer to 7 - COOLING/

ACCESSORY DRIVE/DRIVE BELTS - INSTALLA-
TION).

4. Check belt indexing marks.

BELTS-DRIVE

DIAGNOSIS AND TESTING

ACCESSORY DRIVE BELT

VISUAL DIAGNOSIS

When diagnosing serpentine accessory drive belts,
small cracks that run across the ribbed surface of the
belt from rib to rib , are considered normal. These are
not a reason to replace the belt. However, cracks run-
ning along a rib (not across) are not normal. Any belt
with cracks running along a rib must be replaced. Also
replace the belt if it has excessive wear, frayed cords
or severe glazing.

Refer to ACCESSORY DRIVE BELT DIAGNOSIS
CHART for further belt diagnosis.

ACCESSORY DRIVE

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