Fig. 114. Location of the drive units on the 280 S and 280 SE models. Checking the tension of the drive belt of the coolant pump and generator is performed in section "A".
1 - crankshaft,
2 - coolant pump,
3 - generator,
4 - air conditioning compressor,
6 - power steering pump,
7 - compressor.
Fig. 115. Location of accessory drive belts on 350 E and 450 E models. Checking the tension of the coolant pump and power steering pump drive belt is performed in section "A".
1 - crankshaft,
2 - coolant pump,
3 - generator,
4 - air conditioning compressor,
5 - tension pulley,
6 - power steering pump,
7 - compressor.
After replacing the coolant pump or other units and when replacing pulleys, it is necessary to tighten the drive belts. The belt tension should be checked periodically at certain intervals. A sign of drive belt slippage is the appearance of a clearly audible whistling sound with a sharp increase in engine speed.
Information copied from the website MercedesMAN.ru
The belt tension is checked on the belt section between the coolant pump pulley and the generator pulley, for this purpose it is necessary to use a special device. In the absence of a special device, with moderate pressure on the belt, the deflection should be within 10... 15 mm.
For adjustment on an eight-cylinder engine (coolant pump and power steering pump) loosen the three nuts on the power steering fluid reservoir and use the bolt to tighten the belts and tighten the mounting nuts.
To adjust the six-cylinder engine, loosen the generator mounting bolts and nuts, tighten the belts with a bolt, tighten the mounting bolts and nuts. The adjustment method has changed over the period of production of engines of this series, which must be taken into account when performing work on adjusting the tension of the drive belts.