Usage:
3176 (2YG, 7LG),
3176B (9CK),
C-10 (2PN),
C-12 (1YN) Truck Engines
Reference: See "New Film (Decal) Used In Belt Tightener Group" and "New Belt Tighteners Used In Alternator Mounting Groups" in this issue.
Description of Change: New straps are used in the alternator mounting groups. The new strap has a slot where the alternator fastens to the strap. The slot allows the alternator to pivot outboard in order to take up belt stretch beyond which the automatic spring belt tightener can correct. A new film (decal) indicates the correct belt tightener position and is used with the new strap.
Adaptable To: The new 131-6650 Strap is a direct replacement to the former 9Y-7302 Strap and adaptable to all 3176 (2YG, 7LG) and 3176B (9CK) Truck Engines. The new 131-6655 Strap is a direct replacement to the former 123-0771 Strap and adaptable to all C-10 (2PN) and C-12 (1YN) Truck Engines.
Installation
When a new belt is installed, run the engine for five minutes to allow for initial belt stretch and seating into the grooves. At the end of five minutes, adjust the system as directed below:
With the engine OFF check the belt tightener position. If the indicator (shoulder of the tightener pivot arm) (2) is pointing at the top (long belt) red zone or the bottom (over-travel) red zone of the decal (3), the system needs to be adjusted.
To make an adjustment, loosen the bolts at both ends of the 131-6650 or 131-6655 Strap (1). Loosen the bottom pivot bolt (5) on the alternator. Make the adjustment by swinging the alternator outboard to tighten the belt. Adjust the system to the bottom (tight) side of the center (green) zone of the decal. Do not allow the belt (7) to make contact with the spring tang (4). Tighten the bolts at both ends of the strap and the bottom pivot bolt (5) on the alternator, that were loosened earlier.
NOTE: Do not adjust the system into the bottom (over-travel) red zone. The spring tang (4) on the belt tightener will come in contact with the back of the belt.
NOTE: The tightener should be checked every oil change to insure that it is operating within the center (green) range of the decal. Always check the position of the tightener with the engine OFF.
Typical Alternator Mounting Group