Mercedes-Benz W201 serpentine belt tensioner and replacement
190D 2.0190D 2.5190 2.0190E
What causes the ticking or rattling from the Mercedes-Benz W201 serpentine belt tensioner?
Usually the tensioner's shock absorber or its mounting is worn. The mounting hole at the lower end of the damper easily wears oval, so it moves and rattles. A broken damper or spring also causes tapping. The damper is worth replacing.
How is the serpentine belt replaced on the W201 when the tensioner has no shock absorber?
1. Loosen the tensioner locking bolt (19 mm) about half a turn. 2. Loosen the adjusting nut (13 mm), which releases the belt. 3. Loosen the pump bolts so that the lug does not break. 4. Fit the belt and tighten the adjusting nut carefully.
How is the serpentine belt tension checked?
The scale differs between model years, so the tension is judged by feel. If the plastic indicator is missing, the belt should twist about 90 degrees at its longest free span. If the rubber part of the tensioner has come off, the whole tensioner must be replaced.
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