BMW 5251 Service Manual page 254

117-18
Camshaft Timing Chain
4
Loosen 4 bolts (arrows) from exhaust camshait sprocket
(Torx E10).
Press down on secondary chain tensioner and lock into place
using BMW special tool 11 3 292 or a similar size pin.
NOTE-
Two types of secondary timing chain tensioners are used;
one with two holes, and one with a single hole for the locl<ing
pin tool.
Remove VANOS control unit mounting fasteners at front of
cylinder head.
4
Install sprocltet rotating tool (BMW special tool 11 5 490) on
exhaust camshaft.
-
Rotate exhaust camshaft sprocket clockwise while sliding
VANOS control unit forward to remove from cylinder head.