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This happened to us on our Toyota. We had to replace the Thermostat. But make sure you follow the directions carefully b/c if it is not put in a certain way it will not work properly.

What is your coolant level? If it isn't full, make it full.

The thermostat may be stuck open. It is supposed to close when the temp falls below normal.

Outside temperature is a factor. In extreme cold, the radiator will cool much quicker.

Bad head gasket. If the head gasket is weak, it may allow engine coolant to seap into a cylinder and be thrown out through the exhaust. The engine may operate normally but there would more than likely be little or no heat and you would see white smoke coming from your tail pipe.. alot of smoke. (had this happen before).

All the other answers could cause it. Also not mixing the proper ratio of water to anti-freeze or using straight anti-freeze can cause it.

This is a good question and some of the answers are good, however i don't agree with using straight anti-freeze. I perfer to use straight anti-freeze and that's all we use at the radiator shop that i have worked at for the past 10 years. I think the biggest answer that's been over looked it that your heater core could be plugged up. This is usually easy to diganose. If the engine is up to temperature BOTH hoses going to it should be hot to the touch. If one is cold and the other is hot, your heater core is plugged up. The easiest way to fix this yourself is to go to a car wash that has a wand that u can use. remove both the hoses that go to the heater core and "flush" it out both ways with the wand. Be care full cause to much pressure can make the heater core leak. As far as the thermostat being stuck shut that problem that's easy to diganose also. If the engine is up to temperature the top and bottom radiator hoses should be hot to the touch. If one is cold and the other is hot then there is not proper anti-freeze flow and you need to replace the thermostat.


all good answers : also make sure your radiator cap is sealing if not most heat will escape as engine is running..

Possibilities include: a thermostat that has failed in the open position, low coolant level, air trapped in the coolant system, and a clooged or bad heater core. If your thermostat and coolant level are fine, and you don't have anitfreeze coming out of your cabin heater vents ( this indicates a leaking heater core) or dripping on the floor, I would try flushing out the heater core with a simple old garden hose. It worked like a charm for my mothers car. Keep up with coolant flushes to keep the system clean of dirt and corrosion.

all very good answers!!!, you have to remember that also if you have a bad thermostat that ( all ) of your emission devices they too will not operate the proper way, so as far as if your thermostat goes if it is bad not only no heat but bad operating emission devices, i learned that the hard way... .

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โˆ™ 2015-07-17 17:36:20
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Q: What causes a vehicle to lose heat?
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