This article shows how to overhaul the intake manifold on an e24 M635csi. This may be needed in case the o-rings and rubber sleeves (parts #8 and #5 in the picture) show signs of wear, or if your accumulator needs inspection (rough idling, because of additional air being sucked in through a crack....) or if you simply want to clean the intake necks. Actually I overhauled the complete intake including throttle bodies, idle control valve and part of the cooling circuit, so the pictures will not always show an accurate situation. This post should be read in conjunction with:  xxx which shows the adjustment of the throttle valves. yyy