Honda Bmw 5 Service Manual

							
170-5 
Radiator and Cooling System 
Fan switch  calibration (M52, M62 engine) 
coniprairoi OUt rlgnal 
Auto. ciimilte ~ontioi inpuls via CAN bus 
Electric fan activation: 
Low  speed 
91°C (196°F) 
High  speed 104 C (21 9 F) 
< In models  manufactured after  911998 (M52 TU engine,  M54 
engine. 
M62 TU engine),  the electric cooling  fan is controlled 
by  the  engine  control  module  (ECM) via  the output final 
stage. 
The  output final  stage is mounted on the  fan housing, next  to 
the  fan motor.  The fan is operated using a pulse width modu- 
lated  signal. Fan circuit wiring is protected  by a 50-amp  fuse. 
Electric fan activation is  based on the following inputs  to the 
ECM: 
Radiator outlet temperature 
Calculated catalytic converter temperature 
Vehicle  speed 
* Battery voltage 
Calculated 
A/C pressure 
When  the vehicle is first started,  the ECM activates  the elec- 
tric  fan  briefly  at 20%  of its maximum speed, then switches 
off.  This  is for diagnostic monitoring.  The voltage generated 
by  the fan  when it slows  down (acting  as a generator) must 
match the  stored rpm values  in the fan output stage  toconfirm 
that the  fan is operating correctly. 
NOTE- 
If the ECM fault  memory  indicates a  cooling fan fault,  check 
that  the fan  is not  seized  and that it spins  freely. 
When 
A/C is  switched ON, the electric fan  is not  immedi- 
ately  turned  on. 
After  the engine  is switched 
OFF the fan  may continue to 
run at varying  speeds  for up to 10 minutes,  based on cal- 
culated  catalyst  temperature. 
Transmission fluid heat exchanger 
Automatic transmission fluid lines circulate transmission fluid 
(ATF)  to and from a heat exchanger  at the radiator. 
All 6-cylinder 
models andV-8 models produced to  911998 are 
equipped with a transmission cooler located  in a cooling cas- 
sette  in front  of the  radiator.   
						

							
.. - - 
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   
						

							
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.   
						

							
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.   
						

							
Radiator and Cooling System 
Check  for cloggedlplugged  radiator or coolant passages. 
Cooling system pressure test 
A cooling system pressure tester is  used to test  for coolant 
leaks,  including internal ones. Common sources  of internal 
coolant leaks  are a faulty cylinder  head gasket, a 
craclted cyl- 
inder  head,  or a cracked engine block. 
WARNING- 
At  normal  operating  temperature  the cooling system is pres- 
surized.  Allow the system  to cool  before  opening.  Release 
the  cap  slowly  to allow  safe release ofpressure. 
4 With  engine cold,  install pressure tester  (BMW special tools 
17 0 002117 0 005 or equivalent)  to expansion tank.  Pressur- 
ize  system to specification listed  in Table  a. Cooling  system 
test  pressures. 
Pressure should  not drop more than  0.1 bar  (1.45  psi) for 
at  least two  minutes. 
. If pressure drops  rapidly and there is  no sign  of external 
leakage, cylinder  head gasket may  be faulty.  Perform com- 
pression  and leak-down  tests. 
Test  expansion 
tank cap using  pressure tester with correct 
adapter (BMW special tool  17 
0 007 or equivalent). Re- 
place faulty  cap or cap  gasket. 
Table  a. Cooling system test pressures 
0021663 I Component l~est pressure 
Radiator 
11.5 bar (21.75 psi) 
Radiator  cap 
12 bar (29 psi) 
CAUTION- 
Exceeding the specified  test pressure  could damage  the ra- 
diator  or other svstem 
com~onents.   
						

							
170-1 0 
I Radiator and Cooling System 
Combustion chamber leak test 
- If you suspect  that combustion  chamber  pressure  is leaking 
into  the cooling  system  past the cylinder  head gasket, use  an 
exhaust  gas analyzer  to test  the vapors  rising from  the cool- 
ant  at the  expansion  tank. 
CAUTIO& 
Use an extension tube above the reservoir neclc to main- 
tain  distance between  the top  of the coolant  and the gas 
analyzer 
nozzle. The  gas  analyzer  is easily damaged  if it  is 
allowed  to inhale liquid  coolant. 
* While running engine  to checlc for causes  of overheat- 
ing, observe coolant  temperature carefully in order to 
avoid  engine damage. 
Thermostat 
If the engine overheats  or runs  too cool and  no other  cooling 
system tests indicate  trouble, the thermostat may be faulty. 
In 
V-8 models  and 6-cvlinder  models nroduced afler 911 998 
(M52TU or M54 engne), rheelecrricaily heated  rhermostal IS 
mon tored by [he OBD II diagnostlc software The fault  may ic 
in the DME software  or hardware,  or it may  lie in the  wiring  to 
the thermostat.  See 
OED On-Board Diagnostics. 
Coolant, draining and filling 
(6-cylinder models) 
WARNING - 
Allow the cooling system  to cool before opening or draining 
the cooling system. 
- Raise front  of car  and  support  safely. 
WARNING - 
Make sure the car is stable and well supported  at all  times. 
Use  a professional automotive lift 
orjack stands designed for 
the  purpose.  A floor jack is not  adequate support. 
- Remove splash shield from  under  engine. 
4 Loosen  radiator  bleed screw  at top  radiator fitting (arrow). 
- Remove cap from  radiator  expansion  tank. Set temperature 
controls to 
full warm. 
gallon  pail underneath  radiator.   
						

							
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)   
						

							
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.   
						

							
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)   
						

							
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.