BMW 1989-1995 525i Service Manual page 21

Overheating
FUNDAMENTALS FOR THE DO-IT-YOURSELF OWNER
Low Oil Pressu re
010-13
" the temperature gauge need le goes into the red band on
the gauge face or the check control displays "COOLANT
TEMP", the coo lant temperature is too high, Find a safe place
to stop and turn the engine off. Open the hood and allow the en-
gine to cool until the tempe rature gauge needle is at the lower
third of the scale . Continuing to drive an overheated car can
cause extensive engine damage.
WARN/NG-
Do not remove the coolant reservoir or radiator cap
with the engine hot. Undoing either could spray hot
coolant and cause burns
or
damage the engine.
CAUTlON-
Do not add cold water
or
coolant to
a
hot engine.
Engine damage could result /rom the sudden tem-
perature change .
NOTE-
If the engine cannot be safely turned off, make sure the
air conditioner is off and turn the heater to high. This will
help cool the engine until
a
safe stopping place can be
reached.
Overheating may be caused by low coolant level or a darn-
aged engine drive belt. Visually check the coolant level and en-
gine belts as described in 020 Maintenance Program. If the
coolant level is low. check the filler cap, hoses, clamps and ra-
diator for signs of leakage . Check for leaks at the water pump
on the front of the engine.
" no leaks are found, add coo lant after the engine has
cooled. The car can be driven. but have the cooling system
thoroughly checked as soon as possible. If replacement cool-
ant is not available, then plain water can be used. but the cool-
ant should later be drained and refilled with the proper mixture
of anti-freeze and water.
If steam is coming from the engine compartment then there is
most likely a burst coolant hose or a large leak in the cooling
system. To find the leak. look for signs of coolant leakage on
hoses, at hose connections. or on the radiator. Let the engine
cool thoroughly, then add coolant or water to fill the system and
start the engine . If a great deal of wate r or coolant flows out of
the hole. then the car should not be driven until repa irs are
made.
If
there is a slight seepage. then it may be possible to
drive a short distance , adding coolant as needed .
If either the red engine oil pressure wam ing light come s on or
the check control displays "ENGINE OIL PRESS" anytime the
engine is running. immediately stop the car and turn off the en-
gine. Do not run the engine at all and have th e car towed . " the
light or grap hic display remains on. do not run the car at all.
Have it towed.
NOTE-
Detailed information on checking the oil pressure is
covered in 119 lubrication System.
Brake Fluid Level
The red brake fluid level warning light may be an indicator of
brake fluid loss. Problems with the brake system should be
checked and repaired immedi ately. See 340 Brakes for more
information.
Check Engine Warning Light
If the "CHECK ENGINE " warn ing light comes on or flashes, it
indicates that an emissions-related fault has occurred. Faults
such as a failed oxygen sensor or a faulty fuel injector can turn
the light on. causing the exhaust or evaporative emissions to
exceed a specified limit. The engine can be safely driven with
the light on. although the emission systems should be checked
as soon as possible. See 100 Engine-General for more in-
formation on the Check Engine Light and the On -board diag-
nostic system.
Dim Lights
Head lights and instrument panel illumination that are dim or
gradually gelling dimmer generally indicate a problem with the
battery or charging system . The battery charge indicator light
may come on as the lights are dimming . In e ither case , the en-
gine and accessories are running off of the battery alone . and
will soon discharge it altogether.
" possible, do not stop the engine unless you have the capa-
bility to jump start it. There may not be enough power in the
starting system to restart the engine . Instead, turn off as many
electrical consumers as possible. This will reduce the current
drain and will allow the car to be driven farther before you lose
all battery power.
With the engine and ignition off, check for loose or corroded
ballery cables or wires at the ballery or the alternator. Discon-
necting, clea ning, and reinstalling corroded wires and con nec-
tors may solve the problem. Also check drive belt tension as
described in 020 Maintenance Program.
EMERGENCIES