BMW 1989-1995 525i Service Manual page 110

116-12
CYLINDER H EAD AND VALVETRAIN
2. With the cylinder head mounted to an appropr iate work
stand. remove the spark plugs and install BMW special
tool t 1 3
26 0/11
3 270 to the top of the cylinde r head.
Do not over tighten the tool mounting bolts in the spark
plug holes. See Fig. 26.
Fig . 26. Special BMW tool no . 11 3260 (A) with adaptor 1 327018).
Tool mounting bolts (arrow s) thread into spark pl ug holes.
Tightening Torque
• BMW special tool 11 1
260/ 11
3 270
to cylinder head 23 Nm (17ft-lb)
NOTE -
BMW special
1001 11
3260 is for the BMW M42 4-cylin·
der twin-cam engine_BMW special tool no.
11 3
2 70 is
a
two-cylinder adaplor for tool no. 11 3260.
3. Tu rn the tool eccentric shaft until pressure is applied to
the camshaft bearing caps. See Fig. 27.
.
...
Fig . 27. Speciat loot (ecceruoc shaft) being turned to apply pressure
to camshaft bearing caps.
CYLINDER HEAD DISASSEMBLYAND ASSEMBL Y
4. Remove the bearing cap mounting nuts.
5. Slowly release the pressure on the camshaft bearing
caps by turning the eccentric shaft. Remove the bear-
ing caps and camshaft. Repeat the procedure on the
remaining camshaft.
6. Remove the camshaft carriers by pulling them straight
up. being careful not to let the hydraulic cam followers
fall out.
CA UTION -
• Do not let the hydraulic cam fol/owers fall out
as
Ihe camshaft carrier is removed. Special suction
cups are available from BMW (special
1001
no. 11
3 250) 10 hold the hydraulic cam fol/owers in
place during carrier removal.
• The cam followers should be stored in an uprighl
pos ition.
7. Remove the valves using a valve spring compress or.
Label each valve assembly as it is removed. Remove
and discard the valve stem oil seals from the valve
guides.
NOTE -
A
special valve spring compressor assembly is avail-
able from BMW for the M50 engine (BM W special tool
no.
11 1
067. no.
11 1
068. no.
11 1
051 and
11 1
052).
Reassembly is the reverse of disassembly. Prior to installa-
tion. check all components for wear as described below under
Cylinder Head Reconditioning. Be sure all parts are in-
stalled in their original positions. Lubricate the camshafts prior
to installation. When installing the camshafts into the cylinder
head. position them so that the lobes for cylinde r no. 1 are
pointing up and towards each other. See Fig. 28.
Fig. 28. Camsh afl correctly positioned for reassembly so that cylinder
no. 1 lobes face each other.