BMW 5251 Service Manual page 137

.-
Cylinder Head Removal and Installation
4
Rotate camshafts until intake and exhaust lobes for cylinder
1 face each other (arrows).
CAUTION-
Be sure that cranlcshaft is stillpositioned at least 30" away
from TDC.
-
Place bearing caps on cams, but do not install retaining nuts.
4
Fit BMW special tool 11 3 260 (A) and 11 3 270 ( B ) to cylin-
der head over intake camshaft and screw long bolts (arrows)
into spark plug threads.
CAUTIOI\C
Do not overtighten bolts in spark plug holes.
Turn eccentric shaft of special tool to pretension bearing
caps. Install and torque nuts on intake camshaft bearing
caps.
Tightening torque
Camshaft bearing
cap
to cylinder head
(M7)
14
Nm
(10
ft-lb)
Release tension on eccentric shaft and remove BMW special
tools 11 3 2601270.
Repeat procedure for exhaust camshaft.
CAUTION-
After the camshafts are installed, a minimum waiting time is
required for the hydraulic lifters to 'bleed down" before bring-
ing the crankshaft andpiston back to top deadcenter. When
the camshafts are removed, the hydraulic lifters can expand.
This expansion can cause increased valve lift when the cam-
shafts are bolted down, possibly resulting in piston interfer-
ence.
Crankshaft I valve timing waiting times
68.F
(20°C) and higher
4
minutes
50-68"F(10-20°C)
11
minutes
32-5O0F(O-10°C)
30
minutes