BMW 1989-1995 525i Service Manual page 108

116-10
CYLINDER
HEAD
AND VALVETRAIN
To disassemble cylinder head
(M30 engine)
1. Remove the cylinder head as described in 113 Cylin-
der Head Removal and Installation.
2. Remove the oil sprayer bar mounting bolt from the cen-
ter of the head. Discard the bolt and the crush-type
washers .
3. Adjust all valve clearances so that the hole in the ec-
centric cam points inward (maximum clearance) .
4. Rotate the camshaft until the cutouts in the front flange
are aligned with the guide plate mounting bolts on the
front of the cylinder head. Remove the two bolts.
NOTE-
At this point. the valve spring pressure on the camshaft
must be relieved. This can be don e in one of two ways .
The lirst method requires the BMW special tool ( BM W
tool no. I t 1 060). which
is a
large press that m ounts
over the top of the entire head and presses do wn on all
of the rocker arms. The second method
is
to manually
lever the necessary rocker arms down using appropri-
ate tools. Once the pressure on the camshaft is re-
lieved, it can be easily withdrawn from the head.
5. Where available, install BMW special tool no. 11 1 060
to the top of the cylinder head and tighten the clamp ing
nuts on the exhaust side first. Then tighten the intake
side clamping nuts, making sure the valve heads don't
contact each other. Pull the camshaft out of the head.
WARNING-
• When tightening down the BMW special tool, be
sure to tighten the exhaust side first to prevent
damaging the valves.
• The BMW special tool may not work on cylinde r
heads with non -factory (aftermarket) camshafts .
II an aftermarket camshalt
is
installed, watch th e
valves as the tool
is
slowly tightened into plac e.
6. If the special tool is not available, rotate the camshaft
until the least number of rocker arms are exerting pres-
sure on the camshaft. Relieve the pressure on the re-
maining rocker arms by levering them down using a
helper (s). and pull the camshaft out of the head .
WARNING-
The val ves are under considera ble pressure /rom
the valve springs. Use extreme care when depress -
ing the rocker arms. Wear hand and eye protection.
7. Remove the rear cover plate from the back of the head.
Note the location of the sealing washer and G-ring on
one of the cover mounting bolts.
CYLINDER HEAD DISASSEMBLYAND ASSEMBLY
NOTE-
Always replace the rear cover sealing washer and 0 -
ring to prevent oil leaks.
8. Remove the rocker arm retainers by sliding the rocker
arms and thrust rings to the side and prying off the thin
retaining rings. See Fig. 23.
Fig . 23. Remove rocker arm retaining ring
b
y sliding rocker arm and
thrust ring to one side. Pick off retaining ring using a small
screwdriver.
9. Remove the threaded end plugs from the front and rear
of the rocker arm shafts.
NOTE-
II the shaft turn s while try ing to remo ve the plug. place
a
cylinder head bolt in
a
cylinder head bolt hole.
10. Remove the rocker arm shafts by either driving them
out using a long drift or pulling them out using a slide
hammer that threads into the threaded end of the rock-
er arm shaft. Catch the springs as shafts are removed.
CAUTION-
II drifling the shaft ou t, strike the drift using firm ,
hard blows while holding the head steady. Tap -
ping on the drift will cause the end of the shaft to
mushroom, making it difficult to remove and pos-
sibly damaging the head. II the end of the shalt
does become mushroomed, use
a
small grinding
stone or equivalent to redress the end of the shaft.