BMW 1989-1995 525i Service Manual page 109

CYLINDER HEAD AND VALVETRAIN
116-11
\)---( ' \ e
NOTE -
Label all parts as they are removed so they can be reo
installed in their original positions. The M30 cylinder
head
uses a two-piece rocker
arm shaft. The intake-
side shafts are different from the exhaust s ide shafts as
are the front and rear sections of each shaft.
11 _ Remove the valves using a stand ard C-type valve
spring compressor. Label each valve assem bly as it is
removed. Remove and discard the valve stem oil seals
from the valve guides.
Reassembly is the reverse of disassem bly. Prior to installa-
tion. check all comp onents for wear as described below under
Cy linder Head Reconditioning. Be sure all parts are in-
stalled in their original positions. When installing the rocker
arm shafts . the longer of the two shafts goes towards the front
of the cylinder head. with the plugged ends facing out. Make
sure the cutouts for the head bolts are correctly aligned and
the oil holes for the rocker arms face the valve stems. Use
Loctite® 270 or equivalent when installing the rocker shaft
end plugs.
When installing the oil sprayer bar, make sure the arrow on
the tube faces the front of the cylinder head and the new cen-
ter mount ing bolt has a new crush-type washer on either side
of the tube. See Fig. 24. If the arrow is not vis ible, turn the tube
upside down and position it on the cylinder head. The oil holes
should be directly above the cam lobes.
Fig, 24. Oil sprayer bar correctly installed with arrow (A) facing Iront.
CAUTfON -
An incorrectly installed or loose oil sp rayer bar will
cause accelerated camshaft wear. Be sure to use
a
new center bolt and new washers . If the old bolt
is reinsta lled. there is danger of it loose ning.
NOTE -
A new type sprayer bar hollow bolt was introduced by
BMW in 1993. The new bolt is pre-coated with
a
locking
compound and should not be reused once torqued. The
new type bolt can be identified by the groove cut into the
boft head and replaces the earlier type bolt. See Fig. 25
Fig. 25. New typ e hollow bolt with machined groove in boll head
(arrow) and locking compound on threads.
Lubricate the camshaft prior to installation. II the camshaft
is being replaced. transfer the camshaft flange parts from the
old shaft to the new shaft .
Tightening Torques
• Oil sprayer bar to cylinder head (new hollow
bolt and washers) . . . _. . . . . 11 to 13 Nm (8 to 10 ft-lb)
• Ignition rotor adaptor (install with
L oct ite (~
270
or equivalent) _ 23 ± 1 Nm (16.5
± 0.5
It-lb)
• Flange to camshaft (large nut) 145
±
5 Nm (107
±
3 ft-Ib)
• Exhaust manifold to cylinder head 15 Nm (11 ft-lb)
• Intake manifold to cylinder head 22 Nm (17 ft-lb)
To disassemble cylinder head
(M50 engine)
Special BMW service tools are highly recommended for re-
moving and installing the camshafts and disassembling the
M50 cylinder head .
WARNING-
Removal of the camshafts without the special tools
can result in personal injury and/or cylinder head
damage. Be sure to read the procedure throug h be-
fore starting
a
j ob.
CAUTION -
The process of evenly loosening the camshaft
bearing cap nuts is NOT an acceptable method of
remo ving the camshafts. The special tools shoutd
always be used to remo ve the camshafts.
1. Remove the cylinder head as describ ed in 113 Cylin-
der Head Removal and Installation.
CYLINDER HEAD DISASSEMBLY AND ASSEMBLY