Cooling System. Bleeding; Mechanical (Viscous Clutch) Cooling Fan; Removing And Installing - BMW 5251 Service Manual

Radiator and Cooling System
Cooling system, bleeding
Trapped air in the cooling system can prevent proper coolant
circulation and overheating. Wheneverthe coolant is drained
and filled, bleed the cooling system to remove trapped air.
4
Loosen bleed screw (arrow) on radiator expansion tank.
-
Set temperature controls in passenger compartment to full
warm, set blower to low setting and turn ignition to ON posi-
tion (do not start engine).
CAUTIOIG
On late model cars with latent heat pump, do not turn ignition
to ON position.
-
Slowly add coolanUdistilled water mixture to expansion tank
until it spills from bleed screw. When coolant spilling from
bleed screws is free of air bubbles, tighten screw and replace
cap on expansion tank.
Run engine until it reaches operating temperature,
-
After engine has cooled, recheck coolant level.
Top up so that coolant level indicator is at MAX.
-
If trapped air cannot be bled manually, pressure-bleed sys-
tem using cooling system pressure tester.
CA UTlON--
Always use genuine BMW coolant or its equivalent to avoid
the formation of harmful, clogging deposits in the cooling sys-
tem.
Tightening torque
Radiator bleed
screw
to radiator
2.5
Nm
(22
in-lb)
Mechanical (viscous clutch) cooling fan,
removing and installing
The procedure given here describes the removal of the me-
chanical fan and fan shroud. It is possible to remove the fan
without the shroud.
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Working at top of fan shroud:
Remove expansion tank bleed screw (arrow) and expan-
sion tank locking tabs.
Push top of expansion tank toward engine and lift to free
from lower mounts.
-
Remove two expansion rivets in upper corners of fan shroud.
Unclip expansion tank bleed hose located under shroud.