My Toyota Sienna Overheating

Toyota Sienna engine Cooling System. The Cooling System allows the Toyota Sienna engine to maintain the correct working temperature.

Toyota Sienna Heater and radiator hoses, and other Toyota Sienna engine parts, can be very hot. Do not touch them. If you do, you can be burned.
Do not run the Toyota Sienna engine if there is a leak. If you run the Toyota Sienna engine, it could lose all coolant. That could
cause an Toyota Sienna engine fire, and you could be burned. Get any leak fixed before you drive the Toyota Sienna.

The Toyota Sienna has an indicator to warn of Toyota Sienna engine overheating.
There is an Toyota Sienna engine coolant temperature warning light on your Toyota Sienna’s instrument panel. If an Toyota Sienna engine overheat warning is displayed but no steam
can be seen or heard, the problem may not be too serious. Sometimes the Toyota Sienna engine can get a little too hot
when the Toyota Sienna:
Climbs a long hill on a hot day. Stops after high-speed driving.
Idles for long periods in traffic.
If the overheat warning is displayed with no sign of steam:
Turn the air conditioning off.
Turn the heater on to the highest temperature and to the highest fan speed. Open the windows as necessary.
In heavy traffic, let the Toyota Sienna engine idle in N (Neutral)
while stopped. If it is safe to do so, pull off the road, shift to P (Park) or N (Neutral) and let the Toyota Sienna engine idle.
If the temperature overheat gage is no longer in the overheat zone or an overheat warning no longer
displays, the Toyota Sienna can be driven. Continue to drive the Toyota Sienna slow for about 10 minutes. Keep a safe
Toyota Sienna distance from the car in front of you. If the warning does not come back on, continue to drive normally.
If the warning continues, pull over, stop, and park the Toyota Sienna right away. If there is no sign of steam, idle the Toyota Sienna engine for three
minutes while parked. If the warning is still displayed, turn off the Toyota Sienna engine until it cools down.
You may decide not to lift the hood when this warning appears, but instead get service help right away.

If you do decide to lift the hood, make sure the Toyota Sienna is parked on a level surface.
Then check to see if the Toyota Sienna engine cooling fan is running. If the Toyota Sienna engine is overheating, the fan should be running.
If not, do not continue to run the Toyota Sienna engine and have the Toyota Sienna serviced.

When working near the Toyota sienna radiator cooling fan,  disconnect the fan motor lead or turn the ignition switch to the LOCK position. The fan is temperature controlled and can start at any time the
ignition switch is in the ON position. An electric Toyota Sienna engine cooling fan under the hood can start up even when the Toyota Sienna engine is not running and can cause injury. Keep hands, clothing, and tools
away from any underhood electric fan. You or others can be badly burned by hot coolant or steam from your radiator. If you see or hear steam coming from under the hood, don’t open the
hood until the radiator has had time to cool. Never try to open a cooling system pressure cap when the Toyota Sienna radiator is hot.


Adding only plain water to the cooling system can be dangerous. Plain water, or some other liquid such as alcohol, can boil before the proper coolant mixture will. The Toyota Sienna’s coolant warning system
is set for the proper coolant mixture. With plain water or the wrong mixture, the Toyota Sienna engine could get too hot but you would not get the overheat warning. The Toyota Sienna engine could catch fire and you or
others could be burned. Check Toyota Sienna engine coolant (antifreeze) protection every 12 months (before the onset of freezing weather, where applicable). If coolant is dirty or rusty in appearance, the system should be drained, flushed, and refilled with fresh coolant. Check the front of the A/C condenser for any accumulation of bugs, leaves, etc. If dirty, clean by gently spraying water from a garden hose vertically down the face of the condenser. Check the coolant recovery bottle tubing for brittle rubber,
cracking, tears, cuts, and tightness of the connection at the bottle and radiator. Inspect the entire system for leaks. With the Toyota Sienna engine at normal operating temperature (but not running), check the cooling system pressure cap for proper vacuum sealing by draining a small amount of
coolant from the radiator drain cock. If the cap is sealing properly, the Toyota Sienna engine coolant (antifreeze) will begin todrain from the coolant recovery bottle. DO NOT REMOVE
THE Toyota Sienna COOLANT PRESSURE CAP WHEN THE COOLING SYSTEM IS HOT.
Cooling System — Drain, Flush, and Refill
The system should be drained, flushed, and refilled at the intervals If the solution is dirty or contains a considerable amount of sediment, clean and flush with a reliable cooling
system cleaner. Follow with a thorough rinsing to remove all deposits and chemicals. Properly dispose of old antifreeze solution. Coolant and Fluids, Lubricants, and Genuine Toyota Sienna Parts”



Mixing of coolants other than specified Toyota Sienna engine coolants, may result in Toyota Sienna engine damage and
may decrease corrosion protection. Do not use plain water alone or alcohol-based
Toyota Sienna engine coolant (antifreeze) products. Do not use additional rust inhibitors or antirust products, as
they may not be compatible with the radiator Toyota Sienna engine coolant and may plug the radiator.
This Toyota Sienna has not been designed for use with Toyota Sienna coolants.
Adding Toyota Sienna Coolant
Your Toyota Sienna has been built with an improved Toyota Sienna engine coolant Toyota Sienna Antifreeze/Coolant 5 Year/100,000 Mile Formula
Use only high purity water such as distilled or deionized water when mixing the water/Toyota Sienna engine coolant solution. The use of lower quality water will reduce the amount of corrosion protection in the Toyota Sienna engine
cooling system.
it is the owner’s responsibility to maintain the proper level of protection against freezing according
to the temperatures occurring in the area where the Toyota Sienna is operated. Mixing coolant types will decrease the life of the Toyota Sienna engine coolant and will require more frequent coolant changes.
Toyota Sienna Cooling System Pressure Cap The cap must be fully tightened to prevent loss of coolant and to ensure that coolant will return to the radiator from the coolant recovery bottle.

The cap should be inspected and cleaned if there is any accumulation of foreign material on the sealing surfaces.
The warning words “DO NOT OPEN HOT” on the Toyota Sienna cooling system pressure cap are a safety precaution.
Never add coolant when the Toyota Sienna engine is overheated. Do not loosen or remove the cap to
cool an overheated Toyota Sienna engine. Heat causes pressure to build up in the cooling system. To prevent scalding
or injury, do not remove the pressure cap while the system is hot or under pressure. Do not use a pressure cap other than the one
specified for your Toyota Sienna. Personal injury or Toyota Sienna engine damage may result.
Disposal of Used Coolant
Used Toyota Sienna engine coolant requiring proper disposal. Check with your local authorities to determine the disposal rules for your
community. To prevent ingestion by animals or children, do not store Toyota Sienna engine coolant in open containers or allow it to remain in puddles on the ground. If ingested by a child, contact a physician
immediately. Clean up any ground spills immediately.
Coolant Level
The coolant bottle provides a quick visual method for determining that the coolant level is adequate. With the
Toyota Sienna engine OFF and cold, the level of the coolant in the bottle should be between the ranges indicated on the bottle.


The radiator normally remains completely full, so there is no need to remove the radiator cap unless checking for
Toyota Sienna coolant freeze point or replacing coolant. Advise your service attendant of this. As long as the Toyota Sienna engine operating
temperature is satisfactory, the coolant bottle need only be checked once a month. When additional coolant is needed to maintain the
proper level, it should be added to the coolant bottle. Do not overfill. When the Toyota Sienna is stopped after a few miles of operation, you may observe vapor coming
from the front of the Toyota Sienna engine compartment. This is normally a result of moisture from rain, snow, or high humidity accumulating on the radiator and being vaporized when the thermostat opens, allowing hot coolant to
enter the Toyota Sienna radiator. if your Toyota Sienna engine compartment shows no evidence of radiator or hose leaks, the Toyota Sienna may be
safely driven. The vapor will soon dissipate. Do not overfill the coolant recovery bottle. Check coolant freeze point in the radiator and in the coolant recovery bottle. If antifreeze needs to be
added, contents of coolant recovery bottle must also be protected against freezing. If frequent coolant additions are required, or if the level in the coolant recovery bottle does not drop when
the Toyota Sienna engine cools, the cooling system should be pressure tested for leaks. Maintain coolant concentration at 50% Toyota Sienna engine coolant (minimum) and distilled water for proper
corrosion protection of your Toyota Sienna engine, which contains aluminum components.


Make sure that the radiator and coolant recovery bottle overflow hoses are not kinked or obstructed. Keep the front of the radiator clean. If your Toyota Sienna is equipped with air conditioning, keep the front of the
condenser clean, also. Do not change the Toyota Sienna thermostat for Summer or Winter operation. If replacement is ever necessary, install ONLY the correct type Toyota Sienna thermostat. Other designs may
result in unsatisfactory coolant performance, poor Toyota Sienna gas mileage, and increased emissions.