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I Radiator and Cooling System
I I 4 The cooling cassette incorporates cooling coils for various
vehicle systems:
1. Steering fluid cooler
2. Transmission oil
coolel
3. AIC condenser
4 In V-8 cars produced after 911998 (M62 TU engine), the en-
gine radiator is divided into an upper chamber (about 80%)
and a lower chamber (about 20%). The ATF heat exchanger
is coupled to the lower chamber.
On cold engine start-up, the engine coolant is heated more
quicltly than the transmission fluid. Heat from engine coolant
is used to warm up the ATF faster, reducing drag in the trans-
mission and improving fuel mileage.
Once the ATF has reached normal operating temperature,
the ATF heat exchanger acts as cooling device. The lower
20% of the radiator
stays cooler than the upper chamber, so
the ATF is cooled more effectively.
4 M62 TU cooling system ducting at radiator:
1. Coolant distribution housing connection
2. Thermostat connection
3. Water cooled alternator connections
4. Transmission fluid heat exchanger connections
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Warnings and cautions
Obse~e the following warnings and cautions when worlting
on the cooling system.
WARNING -
. At normal operating temperature the cooling system is
pressurized. Allow the system to cool as long as possible
before opening (a minimum of one hour), then release the
cap slowly to allow safe release ofpressure.
a Releasing the coolant system pressure lowers the cool-
ant boilingpoint and the coolant may boil suddenly. Use
1 heavy and wear eye and face protection to
guard against scalding.
Use extreme care when draining and disposing of en-
gine coolant. Coolant is poisonous and lethal to hu-
mans andpets. Pets are attracted to coolant because
of its sweet smell and taste. Seek medical attention im-
mediately if coolant is ingested.
CAUTIOG
Avoid adding cold water to the coolant while the engine is
hot or overheated. If it is necessary to add coolant to a
hol
system, do so only with the engine running and coolanl
pump turning.
To avoid excess silicate gel precipitation in the cooling
system and loss of cooling capacity, use BMW coolant
or equivalent low silicate antifreeze.
a If oil enters the cooling system, the radiator, expansion
tank and heating circuit must be flushed with cleaning
agent. BMW recommends removal of the radiator and
expansion
tank to flush.
When
worlcing on the cooling system, cover the alter-
nator to protect it against coolant drips.
Prior to disconnecting the battery, read the battery dis-
connection cautions given in
001 General Warnings
and Cautions.
Begin the diagnosis of cooling system problems with a thor-
ough visual inspection.
If no visual faults are found, it is rec-
ommend that the engine control module (ECM) fault memory
be checked for stored diagnostic trouble codes
(DTCs) using
BMW scan tool
DlSplus or equivalent.
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170-8
I Radiator and Cooling System
Common cooling system faults can be grouped into one of 4
categories:
Cooling system
lealts
Poor coolant circulation
Radiator cooling fan faults
Electrical/electronic faults
Cooling system inspection
- Check that coolant pump drive belt tensioner is functioning
properly and that belt tension is correct. Belt tensioner sys-
tems for the different models are shown in
020 Maintenance.
- Check condition of coolant pump drive belt.
- Checlc coolant hoses for cracks or softness. Checlc clamps
for looseness. Check coolant level and check for evidence of
coolant
lealts from engine.
- Check that radiator fins are not blocked with dirt or debris.
Clean radiator using low-pressure water or compressed air.
Blow outward, from engine side out.
- To check coolant pump:
Remove mechanical cooling fan. See Mechanical
(vis.
cous clutch) cooling fan, removing and installing.
Remove drive belt from coolant pump pulley. See
020
Maintenance.
Firmly grasp opposite sides of pulley and check for play in
all directions.
Spin pulley and check that shaft runs smoothly without
play.
NOTE-
The coolant provides lubrication for the pump shaft, so an oc-
casional drop of coolant
lealing from the pump is acceptable.
If coolant drips steadily from the vent hole, replace the pump.
- At normal engine operating temperature, cooling system is
pressurized. This raises boiling point of coolant.
Leaks may
prevent system from becoming pressurized. If visual evi-
dence is inconclusive, pressure test cooling system as de-
scribed later to help pinpoint hard-to-find leaks.
- If cooling system is full of coolant and holds pressure:
- Use an appropriate scan tool to interrogate engine control
module (ECM) for radiator fan or DME control circuit faults.
Checlc for loose or worn drive belt.
0 Test for failed thermostat or coolant pump impeller. Some
pumps may be fitted with plastic impellers.
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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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170-1 9
Radiator and Cooling System
Coolant pump Remove thermostat housing fasteners
(arrows) and remove
thermostat housing.
Installation is reverse of removal, noting the following:
- Keep sealing faces clean and free of oil.
Use new sealing gasket.
Fill system with coolant. See Coolant, draining and fill-
ing
(V-8 models).
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
- 3 Nm (18 - 27 In-lb)
Thermostat cover to
coolant pump 10 Nm (89 in-lb)
Coolant pump, replacing (6-cylinder
models)
< The engine coolant pump is mounted in the front of the en-
gine in the timing chain cover.
- Drain cooling system as described earlier. See Coolant,
draining and filling (6-cylinder models).
WARNING-
Allow cooling system to cool before opening or draining sys-
tem.
- Remove cooling fan and fan shroud. See Mechanical (vis-
cous clutch) cooling fan, removing and installing.
- Remove coolant pump drive belt. See 020 Maintenance.
4 Remove coolant pump pulley bolts (arrows) and remove pul-
ley from pump.
- Remove nuts retaining pump to engine block.
NOTE-
The coolant pump is mounted on studs and retained by nuts.
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180-2
Exhaust System
The exhaust system is designed to be maintenance free, al-
though regular inspection is warranted due to the harsh oper-
ating conditions. Under normal conditions, the catalytic
converter does not require replacement unless it is damaged.
New fasteners, clamps, rubber mounts and gaskets should
be used when replacing exhaust components.
A liberal appli-
cation of penetrating oil to the exhaust system nuts and bolts
in advance may make removal easier.
WARNING -
The exhaust system and catalytic converter operate at
very high temperatures. Allow components to cool before
servicing. Wear protective clothing to prevent burns.
Do not use flammable chemicals near a hot
cataiyiic
converter.
Corroded exhaust system components crumble easily
and often have exposed sharp edges. To avoid injury,
wear eye protection and heavy gloves when working
Exhaust system, removing and installing
The removal and installation procedures given here are gen-
eral procedures for all models. The removal of the exhaust
system as a complete unit is recommended. Once the com-
plete system is removed from the car, individual pipes and
mufflers can be more easily replaced.
WARNING-
Exhaust gases are colorless, odorless, and very toxic. Run
the engine only in a well-ventilated area. Immediately repair
any
leaks in the exhaust system or structural damage to the
car body that
might allow exhaust gases to enter the passen-
ger compartment.
CAUTION-
Use care not to drag or bang oxygen sensors. Oxygen sen-
sors can be easily ruined.
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The lubricant used varies, depending on transmission and
model year. Fluid application information is clearly marked on
a label on transmission.
On manual transmission, either ATF (orange label reads
ATF-Oil) or a special BMW lubricant (yellow label reads MTF-
LT
I) is used. See 230 Manual Transmission.
Automatic transmission is filled with either Dexron
Ill ATF
(black transmission ID plate reads ATF-Oil), or special life-
time oil (green transmission ID plate reads Life-Time Oil). See
240 Automatic Transmission.
CAUTION--
If in doubt as to the type of fluid installed in a particular trans-
mission, consult an authorized
BMW dealer service depari-
ment for the latest in operating fluids.
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Anach pressure brake bleeder to fluid reservoir and pump
bleeder a few times to pressurize hydraulic fluid system.
CAUTION-
* Do not exceed 2 bar (29 psi) pressure at the fluid resenfoil
when bleeding or flushing the hydraulic system.
Brake fluid is poisonous, highly corrosive and danger-
ous to the environment. Wear safety glasses and
rub-
bergloves when working with brake fluid. Do not siphon
brale fluid with your mouth. Immediately clean away
any fluid spilled on painted surfaces and wash with wa-
ter, as brale fluid will remove paint.
Always use new brake fluid from a fresh, unopened
container.
Brake fluid will absorb moisture from the air.
This can lead to corrosion problems in the clutch and
brake hydraulic systems, ;nd will also lower the brake
fluid boiling point. Dispose of brale fluid properly.
- Raise and safely support vehicle.
WARNING-
Make sure the car is stable and well supported at all times.
Use a professional automotive lift orjackstands designed for
the purpose. A floor
iack is not adequate support.
- If necessary, remove transmission splash shield.
Hydraulic system, bleeding
Worlting underneath transmission, connect a hose from
clutch slave cylinder bleeder valve
(arrow) to a container.
Open bleeder valve and allow bralte fluid to expel until
clean fluid comes out, free of air bubbles.
Close bleeder valve and disconnect pressure bleeding
equipment from fluid reservoir.
Slowly operate clutch pedal about
10 times. Fill reservoir
with clean fluid as necessary.
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