Since he has not responded, I will assume the problem is still present. The belt tensioner behind the power steering pump has a tension gauge on the cast bracket. The arrow on the gauge must be to the left facing the engine to confirm the belt is properly tight. A 17 mm socket and short extension is used to loosen the tensioner pivot, then a 13 mm wrench is used on the tensioner bolt to move the tensioner pulley. Turn the 13 mm bolt clockwise.

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81 300CD (sold) 1972 280 SEL 4.5 (sold) 1966 250 S 4 spd (sold) 1974 450 SL (sold) 86 BMW 325ES (sold), 1973 280C (sold) 1988 300 SE.