1999 Lexus LS400 engine overheat

GAUGES, METERS AND SERVICE REMINDER INDICATORS
59
ENGINE COOLANT
TEMPERATURE GAUGE
13L002±2

Normal range
The gauge indicates the engine coolant temperature
when the ignition switch is on. The engine operating
temperature will vary with changes in weather and
engine load.
If the needle points to the red zone or higher, stop your
vehicle and allow the engine to cool.
Your vehicle may overheat during severe operating
conditions, such as:
 Driving up a long hill on a hot day.
 Reducing speed or stopping after high speed driving.
 Idling for a long period with the air conditioning on in stop±and±go traffic.
 Towing a trailer.
NOTICE
Do not remove the thermostat in the engine
cooling system as this may cause the engine to
overheat. The thermostat is designed to control the flow of coolant to keep thetemperature of the engine within the specifiedoperating range.
Do not continue driving with an overheatedengine. See ºIf your vehicle overheatsº onpage 347.

STARTING AND DRIVING
273
NOTICEA large amount of unburned gases flowing intothe three±way catalytic converter may cause it tooverheat and create a fire hazard. To prevent this
and other damage, observe the following precautions:
Use only unleaded gasoline.
Do not drive with an extremely low fuel level;running out of fuel could cause the engine tomisfire, creating an excessive load on thethree±way catalytic converter.
Do not allow the engine to run at idle speed formore than 20 minutes.
Avoid racing the engine.
Do not push±start or pull±start your vehicle.
Do not turn off the ignition while the vehicle ismoving.
Keep your engine in good running order.Malfunctions in the engine electrical system,electronic ignition system/distributor ignitionsystem or fuel system could cause anextremely high three±way catalytic converter
temperature.
If the engine becomes difficult to start or stallsfrequently, take your vehicle in for a check±upas soon as possible. Remember, your Lexusdealer knows your vehicle and its three±waycatalytic converter system best.

STARTING AND DRIVING
280
HOW TO START THE ENGINE
Before cranking
1. Apply the parking brake firmly.
2. Turn off unnecessary lights and accessories.
3. Put the selector lever in ºPº. If you need to restart the
engine while the vehicle is moving, put the selector lever
in ºNº. A starter safety device will prevent the starter
from operating if the selector lever is in any drive
position.
4. Depress the brake pedal and hold it to the floor until
you are ready to drive off.
Starting the engine
Before starting the engine, be sure to follow the
instructions in ºBefore crankingº.
Normal starting procedure
The multiport fuel injection system/sequential multiport
fuel injection system in your engine automatically
controls the proper air±fuel mixture for starting. You can
start a cold or hot engine as follows:
1. With your foot off the accelerator pedal, crank the
engine by turning the key to ºSTARTº. Release it when
the engine starts.
2. After the engine runs for about 10 seconds, you are
ready to drive. If the weather is below freezing, let the engine warm up
for a few minutes before driving. Do not leave the vehicle
while the engine is warming up.
If the engine stalls ...
Simply restart it , using the correct procedure given in
normal starting.
If the engine will not start
See ºIf your vehicle will not startº on page 342.
NOTICE
Do not crank for more than 30 seconds at a
time. This may overheat the starter and wiringsystems.
Do not race a cold engine.
If the engine becomes difficult to start or stallsfrequently, have the engine checkedimmediately.

STARTING AND DRIVING
290
CAUTION
Be careful when downshifting on a slippery surface.
The abrupt change in engine speed could cause the
vehicle to spin or skid.
(c) Using the º3º, º2º and ºLº positions
The º3º, º2º and ºLº positions are used for strong engine\
braking as described previously.
With the selector lever in º3º, º2º or ºLº, you can start the
vehicle in motion as with the lever in ºDº.
With the selector lever in º3º or º2º, the vehicle will star\
t
in the first gear and automatically shift to the third or
second gear.
With the selector lever in ºLº, the transmission is
engaged in the first gear.NOTICE
Be careful not to overrev the engine. Watch the tachometer to keep engine rpm from going intothe red zone. The approximate maximumallowable speed for each position is givenbelow for your reference:
º3º 160 km/h (99 mph) . . .
º2º 104 km/h (65 mph) . . .
ºLº 68 km/h (42 mph) . . . .
Do not continue hill climbing or hard towing for
a long time in the º3º, º2º or ºLº position. Thismay cause severe automatic transmission
damage from overheating. To prevent suchdamage, º4º position should be used in hillclimbing or hard towing.

STARTING AND DRIVING
293
(f) Good driving practice
If the transmission repeatedly upshifts and
downshifts between the fourth and overdrive gears
when climbing a gentle slope, shift the selector lever
to the º4º position. Be sure to shift the selector lever
to the ºDº position after climbing the slope.
 When towing a trailer, in order to maintain efficient
engine braking and electrical charging performance,
do not use overdrive. The selector lever must be in
the º4º position.
CAUTION
Always keep your foot on the brake pedal while stopped
with the engine running. This prevents the vehicle from
creeping.
NOTICE
Do not hold the vehicle on an upgrade with the accelerator pedal. This can cause thetransmission to overheat. Always use the brakepedal or parking brake.
(g) Rocking your vehicle if stuck

DRIVING TIPS
324
Do not rest your foot on the brake pedal while
driving. It can cause dangerous overheating,
needless wear, and poor fuel economy.
 To drive down a long or steep hill, reduce your
speed and downshift. Remember, if you ride
the brakes excessively, they may overheat and
not work properly. See page 288.
 Be careful when accelerating, upshifting,
downshifting or braking on a slippery surface.
The abrupt change in engine speed, such as
sudden acceleration or engine braking, could
cause the vehicle to spin or skid.
 Do not drive in excess of the speed limit. Even
if the legal speed limit permits it, do not drive
over 140 km/h (85 mph) unless your vehicle has
high±speed capability tires. Driving over 140
km/h (85 mph) may result in tire failure, loss of
control and possible injury. Be sure to consult
a tire dealer to determine whether the tires on
your vehicle are high±speed capability tires or
not before driving at such speeds.
 Do not continue normal driving when the
brakes are w et. If they are wet, your vehicle will
require a longer stopping distance, and it may
pull to one side when the brakes are applied.
Also, the parking brake will not hold the vehicle
securely.WINTER DRIVING TIPS
Make sure you have a proper freeze protection of
engine coolant.
Your coolant must contain ethylene±glycol type coolant
for a proper corrosion protection of aluminum
components. Use ºToyota Long Life Coolantº or
equivalent. See ºChecking the engine coolant levelº on
page 409 for instructions.
NOTICE
Do not use alcohol type antifreeze or plain water
alone.
When it is extremely cold, we recommend to use 60%
solution for your Lexus, to provide protection down to
about ±50 C (±58 F). Do not use more than 70%
solution for better coolant performance.
Check the condition of the battery and cables.
Cold temperatures reduce the capacity of any battery, so
it must be in top shape to provide enough power for
winter starting. Page 443 tells you how to visually
inspect the battery. Your Lexus dealer and most service
stations will be pleased to check the battery charge
level.
Make sure the engine oil viscosity is suitable for the
cold weather.

DRIVING TIPS
334
Avoid jerky steering and sharp turns. The trailer could
hit your vehicle in a tight turn. Slow down before
making a turn to avoid the need of sudden braking.
 Remember that when making a turn, the trailer
wheels will be closer than the vehicle wheels to the
inside of the turn. Therefore, compensate for this by
making a larger than normal turning radius with your
vehicle.
 Crosswinds and rough roads will adversely affect
handling of your vehicle and trailer, causing sway.
Pay attention to the rear from time to time to prepare
yourself for being passed by large trucks or buses,
which may cause your vehicle and trailer to sway. If
swaying happens, firmly grip the steering wheel and
reduce speed immediately but gradually. Never
increase speed. If it is necessary to reduce speed,
brake slowly. Steer straight ahead. If you make no
extreme correction with the steering or brakes, your
vehicle and trailer will stabilize.
 Be careful when passing other vehicles. Passing
requires considerable distance. After passing a
vehicle, do not forget the l ength of your trailer and be
sure you have plenty of room before changing lanes.
 In order to maintain efficient engine braking and
electrical charging performance, do not use
overdrive. Transmission must be in the º4º position. 
Because of the added load of the trailer, your vehicle's
engine may overheat on hot days (at temperatures
over 30C [85F]) when going up a long or steep
grade with a trailer. If the engine coolant temperature
gauge indicates overheating, immediately turn off the
air conditioning (if in use), pull your vehicle off the
road and stop in a safe spot. See ºIf your vehicle
overheatsº on page 347 of this manual.
 Always place wheel blocks under both the vehicle
and trailer wheels when parking. Apply the parking
brake firmly. Put the transmission in ºPº. Avoid
parking on a slope with a trailer, but if it cannot be
avoided, do so only after performing the following:
1. Apply the brakes and keep them applied.
2. Have someone place wheel blocks under both the
vehicle and trailer wheels.
3. When the wheel blocks are in place, release your
brakes slowly until the blocks absorb the load.
4. Apply the parking brake firmly.
5. Shift into ºPº and turn off the engine.

DRIVING TIPS
335
When restarting out after parking on a slope:
1. With
the transmission in ºPº position, start the engine.
Be sure to keep the brake pedal depressed.
2. Shift into the º3º, º2º, ºLº or ºRº position.
3. Release the parking brake and brake pedal and
slowly pull or back away from the wheel blocks. Stop
and apply your brakes.
4. Have someone retrieve the blocks.
CAUTION
 Do not exceed 72 km/h (45 mph) or the posted towing
speed limit, whichever is lower. Because instability
(swaying) of a towing vehicle±trailer combination
usually increases as the speed increases, exceeding
72 km/h (45 mph) may cause loss of control.
 Slow down and downshift before descending steep
or long downhill grades. Do not make sudden
downshifts.
 Avoid holding the brake pedal down too long or too
frequently. This could cause the brakes to overheat
and result in reduced braking efficiency.