BMW 5251 Service Manual page 256

11 7-20
Camshaft Timing Chain
4
lnstall BMW special tool 1 I 5 490 on exhaust camshaft.
-
Insert the helical-toothed splined shafl (arrow) into the heli-
cal-toothed sprocket while rotating gears and chain counter-
clockwise with special tool.
CAUTION-
Ensure that the first available tooth engages. It is important
that the exhaust camshaft sprocket be turned only the mini-
mum amount necessary to engage the gear cup. If this pro-
cedure is done incorrectlq: the VANOS system may not fully
function.
-
Install and tighten down VANOS control unit fasteners
Tightening torques
VANOS control unit
to
cylinder head
M6
nuts
10 Nm
(89 in-lb)
M8 bolts
22
Nrn
(17
ft-lbj
-
Press down on secondary timing chain tensioner and remove
lock tool.
Remove primary timing chain tensioner (arrow)
CAUTION-
Timing chain tensioner is under spring tension.
lnstall adjustable primary chain tensioner (BMW special tool
11 4 220) and preload timing chain by tightening to 1.3 Nm
( I I in-lb).