Blue Bird Coachworks 450 LXi, Owner'S Manual

Page: 471 / 684

5-3 Engine Maintenance
450 LXi Owner Manual
~ 5-3-12 ~
Rev. “C”
If the belts are too tight, unnecessary stresses are placed on the pulley bearings and on the belts. This may shorten the
service life of the components.
Remove the belt guard. Inspect the condition and adjustment of the alternator belts and accessory drive belts (if equipped).
To check the belt tension, apply 110 N•m (25 lb ft) of force midway between the pulleys. A correctly adjusted belt will defl ect
9 mm (0.35 inch) to 15 mm (0.59 inch).
If the belt does not require replacement or adjustment, install the belt guard. If the belt requires adjustment or replacement,
perform the following procedure to adjust the belt tension.
If the engine is equipped with a refrigerant compressor (air conditioner), the belt for the fan drive, the alternator, and the
accessories will have an automatic belt tensioner.
If the engine is not equipped with a refrigerant compressor, the alternator is used to adjust the belt tension.
•
•
5-3.12.2 Adjustment
Alternator Belt
Slightly loosen mounting bolt (2) and adjusting nut (1).
Move the pulley in order to adjust the belt tension.
Tighten adjusting nuts (1) and mounting bolts (2). Refer to “Torque Specifi cations”
section of this manual.
Install the belt guard.
If new belts are installed, check the belt tension again after 30 minutes of engine operation
at the rated rpm.
1.
2.
3.
4.
5-3.13 Belt Tensioner - Inspect
It is essential to check the position of the belt tightener in order to maintain the proper belt
tension. A fi lm (decal) is located on the side of the belt tightener. The decal indicates when
the belts have stretched beyond the belt tightener’s ability.
If the pointer (1) is in green zone (3), the belt tension is correct. If the pointer (1) is in the
upper red zone (2), the belt has stretched. The tension must be adjusted or the belt must
be replaced. If the pointer (1) is in the lower red zone (4), the belt is too short. The belt must
be replaced.
Side view of the belt tensioner
(1) Indicator
(2) Upper red zone
(3) Green zone
(4) Lower red zone