BMW E46 Tensioner and Idler Pulley Replacment

Video demonstrating how to remove and replace the main serpentine belt tensioner and idler pulleys on a E46 3 series BMW. Specifically the BMW in the video is a 330xi with the 3.0 litre inline 6 cylinder engine. Tensioner and idler pulley bearings DO wear out over time and if your drive belts begin to make a "growl" or a "grinding" noise odds are that the tensioner pulley bearings are wearing or worn out.

I had to replace just the main serpentine belt idler and tensioner pulley and did not have to replace the air conditioning tensioner as the bearing assembly was fine in that particular pulley.

Always use HIGH QUALITY tools made from high quality hardened steel. Cheap bits will result in stripped or damaged fasteners.

When using your Torx #50 bit make sure you FULLY SEAT the bit into the centre of the bolt otherwise your risk damaging the "star" points on the screw head making future removal or de-tensioning of the belts very difficult.

It is worth mentioning that the tensioner pulley can only be replaced on motors that use a hydraulic tensioner. Early revision of the E46 employed a mechanical spring tensioner and if that pulley fails then you will need to change the ENTIRE tensioner assembly. Idler pulley are the same across the board for the E46s.

BMW part #'s are listed below
Main serpentine tensioner pulley: 11-28-1-748-131 (ADJUSTING PULLEY)
Idler pulley for serpentine belt: 11-28-7-841-228 (DEFLECTION PULLEY)
Main tensioner Torx #50 bolt: 07-12-9-905-534 (FILLISTER-HEAD SCRE)