I'm checking out an '89 745 for a friend. Her engine has a whine at all speeds, not loud, can barely be heard inside the vehicle. Is this normal for a B234 na engine? It sounds like it comes from the lower center of the engine(like where the balance shafts are)
I was checking out an "oil control problem" and when I was cleaning out the flame trap and stuff I noticed the camshaft box was replaced with a used part. I checked the timing belts and balance shaft belts, they look new(I can still read the writing on the timing belt clearly). The timing belt cover had gouges on the inside from an obvious failure of the idler roller. I'm worried that when this engine munched the valve train it may not have been completely repaired.
I've got a B23 and a B230 so I'm not familiar with this one.
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Al Hagenberger '84 245 310K, '87 744 172K

the tension is not set correctly on the balance shaft belt. and maybe they turned the tensioner the wrong direction and into the plastic housing. you do not set the balance shaft belt tight like a timing belt. there is always a certain amount of belt whine anyway if its mild its ok.