Belts - Inspect/Adjust/Replace
784C and 785C Off-Highway Truck/Tractor
Inspection
To maximize the engine performance, inspect the belt for wear and for cracking. Check the belt tension. Adjust the belt tension in order to minimize belt slippage. Belt slippage will decrease the life of the belt.
To check the belt tension, refer to the Engine Specifications, "Belt Tension Chart". A correctly adjusted belt will deflect 13 to 19 mm (0.50 to 0.75 inch).
Note: The belt tension for the engine fan is spring applied. The fan drive belt cannot be adjusted. If the fan drive belt is loose, see Engine Supplement, Disassembly and Assembly, "Belt Tightener - Remove and Install" for instructions on replacement of the spring. If the fan drive belt is cracked or worn, refer to Engine Supplement, Disassembly and Assembly, "Belt Tightener - Remove and Install" for replacement information.
Adjustment
Alternator
(1) Adjusting nuts
(2) Mounting bolt
1. If necessary, remove the belt guard.
2. Loosen mounting bolt (2) and adjusting nuts (1) .
3. Turn adjusting nuts (1) in order to increase or decrease the belt tension.
4. Tighten adjusting nuts (1). Tighten mounting bolt (2) .
5. If necessary, reinstall the belt guard.
If new belts are installed, check the belt adjustment again after 30 minutes of engine operation at the rated rpm.
Refrigerant Compressor
1. Loosen two bolts (3) .
2. Loosen nut (4) .
3. Use nuts (5) to adjust the belt tension.
4. Tighten nut (4) and nuts (5) .
5. Tighten bolts (3) .
Replacement
For applications that require multiple drive belts, replace the belts in matched sets. Replacing only one belt of a matched set will cause the new belt to carry more load because the older belts are stretched. The additional load on the new belt could cause the new belt to break.
Refer to Engine Supplement, Disassembly and Assembly, "Belt Tightener - Remove and Install" for more information on replacement of the belts.
