Harmonic Balancer
From E34 Addicts
Overview
Failure of harmonic balancer will damage all of the accessories including your power steering pump, alternator, water pump and pulleys while creating extra engine vibration.
Diagnostic
Start the car and look at harmonic balancer (the big pulley located under water pump, your crank shaft position sensor is positioned to read the teeth of this pulley. If any wobble or shake is emmited, turn off the car and check for 8 bolts holding the harmonic balancer in place. If any of those bolts are missing, replace and repeat procedure.
Note
Since a faulty balancer can cause extreme load on the V-belt system, you must inspect all the pulleys and replace your belt and tensioner.
