BMW 1989-1995 525i Service Manual page 104

116-6
CYLINDER HEAD AND VALVETRAIN
CAUTlON -
Do not interchange the knock sensor harness
connectors. Serious engine damage may result.
Be sure to label connectors to ensure correct re-
connection.
8. Remove mounting nuts from left and right wiring har-
ness ducting. Lift ducting off cylinder head covers and
set aside.
9. Remove ground wire from rear engine lifting bracket
and disconnect harness connectors from engine cool-
ant temperature sensors at rear of engine. See Fig. 14.
~"c-"-A
00 11533
Fig . 14. Ground wire for ignition COils (A) and coolant temperature
sensors (B , white connector, C, black connecto r).
10. Remove cylinder head cover cap nuts and remove cov-
ers. Remove inner and outer gaskets.
11 . Apply a thin coating of glycerine or suitable rubber lu-
bricant to inner and outer gaskets.
12. Install inner gasket evenly into inner gasket groove in
cylinder head cover, pressing four corners into position
first and working evenly into groove. Repeat for outer
gasket.
13. Apply thin bead of sealer (Hylomar®
sa
23) to gasket
surface at joint where upper timing chain cover meets
cylinder head.
14. Install outer gasket evenly into outer gasket groove in
cylinder head, pressing rear corners into posi tion first
and working evenly into groove.
15. The remainder of installation is reverse of removal. In-
stall all valve cover cap nuts by hand, then tighten even-
ly and in stages, working diagonally from inside to
outside.
VALVE ADJUSTMENT (M20 and M30 engines)
WARNING -
Be sure harness connectors are correctly installed.
especially at knock sensors. Incorrect installation of
connectors at knock sensors may result in serious
engine damage.
Tightening Torque
• Cylinder head cover to cylinder head
and timing chain cover
M6 10 Nm (89 in-Ib)
M7 15 Nm (11 ft-Ib)
VALVE ADJUSTMENT
(M20 and M30 engines)
Valve adjustment should be done as part of scheduled
maintenance. For a listing of recommended adjustment inter-
vals, see 020 Maintenance Program.
A special tool (BMW Tool No. 11 3070) is available to help
turn the rocker arm eccentric when setting valve clearances .
As an alternative , a tool can be easily fabricated from stiff wire
(approximate diameter of 3/32 in.). The valves can be adjust-
ed with the engine hot or cold.
To adjust valve clearance
1. Remove the cylinder head cover as described above.
2. Using a socket wrench on the vibration damper nut.
hand-turn the crankshaft clockwise until the No. 1 cyl-
inder's camshaft lobes are pointing approximately
downward (valves fully closed).
NOTE -
• The no. t cylinder is the one closest to the radiator
end of the engine.
• It
is much easier to reach the crankshaft vibration
damper nut after removing the radiator cooling fan
and plastic radiator cowling as described in 170 RadI-
ator and Cooling System .
• Crankshaft rotation can be done more easily if the
spark plugs are first removed.
3. Measure the valve clearances of the no. 1 cylinder in-
take and exhaust valves using a feeler gauge. See Fig.
15. Compare the measured clearance values with the
specificati ons listed in Table b.
NOTE -
V alve clearance specifications for both the intake
valves and the exhaust valves are the same.