1998 BMW 540i Radiator and Cooling System

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170-1 1
Radiator and Cooling system/
4 Remove drain plug (arrow) at bottom of radiator.
Coolant is poisonous. It is especially lethal to pets. Clean up
spills immediately and rinse the area with
wate,: If coolant is
- Place a 3-gallon pail beneath the engine block. Remove en-
gine block coolant drain plug and drain coolant.
< M52 TU 1 M54 engine: Bloclc drain plug is located on exhaust
side of engine block at cylinder
2 (arrow).
M52 engine:
Bloclc drain plug is located on exhaust side of
engine
bloclc between cylinders 3 and 4.
- Reinstall radiator and engine block drain plugs using new
sealing washers.
- Before refilling radiator:
Switch ignition to
ON. (Do not start engine).
Set temperature controls to full warm.
Set blower control to low.
- Using a coolant mixture of 50% antifreeze and 50% distilled
water, fill expansion tank slowly. Continue until coolant
emerges from bleed screw. Cooling system capacity is listed
in Table c. Cooling system capacity (6-cylinder models).
NOTE-
Be sure radiator bleed screw is loose when filling cooling
system.
Tap water may cause corrosion of radiator, engine and
coolant hoses.
Coolant can be reusedprovided it is clean and less than
two years old. Do not reuse coolant when replacing dam-
aged engine parts.
- Bleed cooling system. See Cooling system, bleeding
Table c. Cooling system capacity (6-cylinder models)
Engine Capacity
M52, M52TU, M54
10.5 liters (1 1.1 US qls)

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170-1 2
I Radiator and Cooling System
Tightening torques
Block drain plug to
block 25 Nm (1 8 ft-ib)
Radiator drain plug to radiator
2-3 Nm (18-27 in-lb)
Coolant, draining and filling (V-8 models)
WARNING -
Allow the cooling system to cool before opening or draining
the cooling system.
- Raise front of car and support safely.
I WARNING- 1
Make sure the car is stable and well supported at all times.
Use a professional automotive lift
orjack stands designed for
I the purpose. A floorjack is not adequate support 1
- Remove splash shield from under engine.
Loosen radiator bleed screw at top radiator fining (arrow).
Remove cap from radiator expansion tank. With ignition
switch in
ON position, set temperature controls to full warm.
Place 5-gallon pail underneath radiator.
4 Remove drain plug (arrow) on bottom of radiator and allow
coolant to drain.
NOTE-
For radiators without drain plug, remove lower hose to drain
radiator.
WARNING
-
Coolant is poisonous. It is especially lethal to pets. Clean up
spills immediately and rinse the area with water. If coolant is
ingested, immediately seek medical attention.

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170-1 3
Radiator and Cooling ~vsteml
< V-8 engine bloclc drain plugs (one shown at arrow) are locat-
ed on each side of engine block (exhaust manifold removed
for photo).
- Place 5-gallon pail underneath engine block coolant drain
plugs.
- Remove engine bloclc coolant drain plugs and drain coolant.
- Reinstall radiator and engine block drain plugs using new
sealing washers.
- Before refilling radiator:
Switch ignition to
ON. (Do not start engine)
Set temperature controls to full warm.
- Set blower control to low.
- Using a coolant mixture of 50% antifreeze and 50% distilled
water, fill expansion tank slowly. Continue until coolant
emerges from bleed screw. Cooling system capacity is listed
in Tabled. Cooling system capacity
(V-8 models).
NOTE- Be sure radiator bleed screw is loose when filling cooling
system.
Tap water may cause corrosion of radiator, engine and
coolant hoses.
Coolant can often be reused provided it is clean and less
than two years old. Do not reuse coolant when replacing
damaged engine parts.
- Bleed cooling system. See Cooling system, bleeding
Tabled. Cooling system
capacity (V-8 models)
M62, M62 TU 12.0 liters (12.7 US qts)
Tightening torques
Block drain plug
25 Nm (18 ft-lb)
Radiator drain plug
2 - 3 Nm (18 - 27 in-lb)

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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.
< 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.

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Radiator and Cooling System
Remove rubber trim strip between top of shroud and radiator.
Using 32 mm wrench
(BMW special tool 11 5 040) on fan
clutch nut (arrow), turn wrench in a clockwise direction
(working from front of car) while counterholding pulley with
BMW special tool
11 5 030. Spin fan off coolant pump.
NOTE-
The radiator cooling fan nut (32 mm wrench) has left-hand
threads.
Unclip AUC (air quality) sensor from shroud,
M54 engine: Disconnect auxiliary coolant pump from base of
fan shroud.
Lift fan and shroud together out of engine compartment.
To replace fan clutch, remove fan mounting bolts and sepa-
rate viscous clutch from fan.
Installation is reverse of removal.
Tightening
torques
Clutch nut to pump
Without
BMW tool 11 5 040 40 Nm (29 ft-lb)
With BMW tool 11 5 040 30 Nm
(22 ft-lb)
Fan to viscous clutch 10 Nm (89 in-lb)
Electric cooling fan, removing and
installing
The electric cooling fan is mounted behind the front bumper,
in front of the
A/C condenser.
- Remove front bumper. See 510 Exterior Trim, Bumpers.
- Remove left and right headlights. See 630 Lights,
- Where applicable, detach horizontal air ducts behind front
bumper and fold to side.
- Disconnect fan electrical connector on right side of radiator
shroud and lay aside.
- Detach wire loom from air duct in front of cooling fan
- Pry out expansion rivets holding air duct. Slide air duct down-
ward to remove.

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170-1 6
I Radiator and Cooling System
- Remove fan and fan shroud mounting fasteners. Slide fan
and fan shroud downward to remove.
- Reinstallation is reverse of removal.
Thermostat, removing and installing
(M52 engine)
The coolant thermostat is installed in a housing at the front of
the engine.
- Drain coolant from radiator and engine block. See Coolant,
draining and filling (6-cylinder models).
WARNING -
Allow the cooling system to cool before opening or draining
the system.
- Remove mechanical cooling fan and fan shroud. See Me-
chanical (viscous clutch) cooling fan, removing and in-
stalling.
- Disconnect coolant hoses from thermostat housing.
- Remove thermostat housing from front of engine.
- Remove thermostat. Note thermostat direction and orienta-
tion before removing.
- Installation is reverse of removal, noting the following:
- Use new O-ring and gasket(s) when installing thermostat
and housing.
NOTE-
Some thermostats have a direction arrow or vent hole near
the edge. Install the thermostat so that either the arrow or
hole are at the top.
Fill system with coolant as described in Coolant, draining
and filling (6-cylinder models).
CAUTION-
Be sure to reconnect ground wire@) at thermostat housing
mounting bolt, where applicable.

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Radiator and Cooling systeml
Tightening torques
Block drain plug to block 25 Nm
(18
it-lb)
Coolant hose clamp (32 - 48 2.
5 Nm (22 in-lb)
mm hose diameter)
Radiator drain plug to radiator
2-3Nm(l8-27in-lb)
Thermostat housing to cylinder
head 10 Nm (89 in-lb)
I Coolant thermostat housing assmbly- - I
Thermostat, removing and installing
(M52 TU or M54 engine)
4 The electric map-controlled thermostat is part of the thermo-
stat housing at the front of the cylinder head.
1. Bolts (M6)
2 Bolt (ME)
3. Housing with thermostat
4. Gasket
- If a faulty thermostat is suspected, use appropriate scan tool
to interrogate
ECM for stored fault codes.
- Drain radiator and engine block. See Coolant, draining and
filling (6-cylinder models).
CAUTION-
Allow cooling system to cool before opening or draining the
system.
- Remove cooling fan and fan shroud. See Mechanical (vis-
cous clutch) cooling fan, removing and installing.
- Disconnect electrical harness connector from thermostat
housina.
4 Lever out retaining clips (arrows) and pull hose fittings off
thermostat housing.
- Unbolt and remove thermostat housing from front of engine.
Loosen nut at top of engine lifting eye to facilitate removal.
- Installation is reverse of removal, noting the following:
Keep sealing faces free of oil.
* Use new sealing gasket.
When reinstalling hose to thermostat housing, install clip
on hose end fitting, then push hose onto housing until it
clicks into place.
Fill system with coolant. See Coolant, draining and fill-
ing (6-cylinder models).

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Tightening torques Block drain plug to block
25 Nm (18 ft-lb)
Radiator drain plug to radiator 2 - 3 Nm (18 - 27 in-lb)
Thermostat housing to
cylinder head 10 Nm (89 in-lb)
Thermostat, removing and installing
(V-8 models)
The electrically-heated thermostat is an integral parl of the
thermostat housing. The operation of the thermostat is moni-
tored by the engine control module (ECM).
- If a faulty thermostat is suspected, use appropriate scan tool
to interrogate ECM for stored fault codes.
- Drain radiator and engine block. See Coolant, draining and
filling
(V-8 models).
WARNING -
Allow cooling system to cool before opening or draining the
system.
- Disconnect mass air flow (MAF) sensor electrical harness
connector. Remove air intake duct together with MAF sensor.
- Remove mechanical cooltng fan and fan shroud. See Me-
chanical (viscous clutch) cooling fan, removing and
in-
stalling.
Disconnect electrical harness connector (arrow) from ther-
mostat housing.
Remove coolant hose from thermostat housing.
NOTE-
M62 engine: Hose is clamped on.
M62 TU engine: Hose is attached with quick-disconnect fit.
ting. Remove clip to disconnect hose.