Insufficient belt tension impairs airflow to the radiator of the cooling system and leads to engine overheating and increased belt wear.
If the belt is too tight, the bearings of the fan drive and tension roller may fail.
When the tension is properly adjusted, the belt should sag 8-10 mm when a force of 40 N (4.0 kgf) is applied midway between the fan pulley and the tension roller.
The belt tension is adjusted by moving the tension roller.
Replacing and adjusting the tension of drive belts for units with a ZMZ-402 engine
We recommend replacing both accessory drive belts if at least one of them fails.
1. Using the “13” head, we loosen the nut of the upper fastening of the idler pulley bracket (the cooling system hoses have been removed for clarity).
2. With the “14” key, we loosen the lower fastening of the tension pulley bracket, holding the bolt with the “12” key
3. We bring the bracket of the tension pulley to the block and remove the belt from the pulleys
4. Passing the belt between the fan impeller and the radiator, remove it
Loosen the top and bottom fasteners of the generator
We bring the generator to the cylinder block.
Remove the belt from the pulleys by passing it through the fan impeller, similar to removing the fan drive belt.
We put new belts on the pulleys.
We tighten the fan drive belt, moving the tension pulley away from the cylinder block, and tighten the upper and lower fastenings of the tension pulley.
We tighten the generator drive belt in the same way, moving the generator away from the cylinder block, after which we tighten the upper and lower generator mounts.
Check the adjustment of the belt tension by applying a force of 4 kgf to the middle of the upper branches.
The deflection of the alternator drive belt should be 8-10 mm, and the fan drive belt should be 7-9 mm.
If necessary, repeat the adjustment.
Replacing and adjusting the tension of the drive belt for units with a ZMZ-406 engine
Using the “12” key, loosen the tightening bolt of the tension roller (for clarity, the engine radiator is removed).
Weaken the belt tension by turning the key "by 10", counterclockwise the tension roller bolt
Remove the belt from the pulleys.
Installing a new belt.
By rotating the tension roller bolt, we achieve a belt deflection of 15 mm under a load of 8 kgf applied in the middle of the horizontal drive branch (between the generator and pump pulleys)
Tighten the tension roller mounting bolt.