BMW E46 Serpentine Belt and Tensioner Replacement
How do you replace the E46 M54 serpentine belt?
The belt can be replaced without removing the fan. First remove the air conditioning belt by turning its tensioner, then turn the serpentine belt tensioner and the large belt comes off. Other parts can be moved out of the front, which gives more room.
Why did the E46 serpentine belt break or why is the tensioner pulley noisy?
The belt often goes as a result of some other fault, so check the pulleys and the water pump. A water pump bearing or pulley can fail and tear the belt. If the tensioner pulleys are noisy, replace both at once, together with the idler pulley next to the alternator, and at the same time both serpentine belts.
Can the E46 belt tensioner pulley be bought separately and what size is the bolt?
The pulley of an older mechanical tensioner can no longer be bought separately; the tensioner is bought as a complete unit. The tensioner bolt is a T50 Torx, not 16 mm. If the tensioner pulley sits crooked and the belt will not seat, the cause can be worn bearings in the tensioner, and the tensioner must be replaced.
What does removing the M47 crankshaft pulley bolt require?
The bolt is long, fine-threaded and extremely tight. The replacement requires a crankshaft locking tool, and according to the factory instructions a 3/4-inch power transmission tool is used for removal. The bolt size is 18 mm.