When the car is completely cool,check the electric fan(s) for smooth rotation.
Clean/check/change the thermo sensor,contact and wire.
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Excavate air pocket in coolant system / check for head gasket leak
This test will kill two birds with one stone.
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MAKE SURE THE COOLANT SYSTEM and ENGINE IS COLD!
RAN THIS TEST IN A WELL VENTILATED AREA ONLY!
You will spill some coolant during this air pocket purge test.......BE
KIND TO THE ENVIRONMENT and ANIMAL please clean up after the test!
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Put the front end on a pair of ramp or park your car on a VERY STEEP HILL (radiator facing top of the hill) .
Top of the coolant reserve tank
Let it ran for 10-15 minutes.
Monitor for air pockets escaping from coolant reserve tank.
Small amount of bubbles is OK at 1-5 minute mark
After the thermostat open up (after 195 F warm up) at
5-12 minute mark or after high idle you should see less bubbles.
If you do not see any in rush of bubbles then your thermostat may be
partially stuck or rusted badly inside the thermostat hosing.
Give the thermostat host few gentle taps.
If you see larger bubbles surfacing after 15 minutes then should do a
hydrocarbon (HC) dye test to test for potential head gasket leak.
Let engine cold down and top off coolant reserve tank.
Start monitor for coolant lost
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A coolant flush is require every 2 years or 24,000 miles.
I recommend the thermostat that has a relief pop-let to reduce the change of burst radiator and coolant hoses.
Make sure you get a new thermostat gasket,black RTV and fresh coolant for the job.
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1. Check coolant level in radiator/reservoir. Do this with the engine cold.
2. Make sure radiator fins are clean
3. If the above 2 do not fix the problem, replace the thermostat.
SOURCE: 2005 Toyota Sienna XLE -
flush the radiator and add new antifreeze,, it breaks down just like oil does, also ,, you could have a sticking thermostat ,, do a visual inspection of the fins in the radiator itself,, they get clogged with bugs and other debris,, its only the air flow through that which cools your car
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Please comment with more "runnng hot" symptoms so we can provide an accurate answer. Runs hot, when? Always, no exception? Does it cool down when at freeway speeds? Cool everywhere except when stopped or at a red light? When heater is ON? When A/C is ON? etc. Thanks!
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