By July 24, 2012 Read More →

Why is my Toyota Overheating?


My Toyota Camry keeps over heating.  I will turn it on and within a mile
it starts to over heat and blows my reservoir cap off .  Then after I turn on
the heater and after a few minutes it cools right down.  But then my heater
blows cold air.  I have changed the water pump, thermostat and did a radiator

I drove it around twice after doing all that for about a mile each time and had no over heat.  And I also left it on for about an hour and a half during which time i took those drives and still no over heat.  Then I turn off the car and wait about 10 minutes and start it back up.  I drive about 1 and it starts to get warm but not as bad as before.

I stopped to get gas and then started on the road again.  I drove about 5 miles then it started to over heat again and the reservoir cap was off again.  I checked my oil dip stick and had no sign of anything but oil.  This has really gotten to
be a head ache and i was wondering if you could help me in anyway?

Thanks John


Hi John, 

I would ALWAYS start my investigation with a cooling system pressure test to rule out any internal or external coolant leaks.
I due suspect a restriction in the radiator from what you have told me, and flushing does pretty much nothing to get rid of the deposits that have formed at the bottom.
Make sure the electric cooling fan at the radiator is coming on, which would cause overheating at idle or slow speeds.  A clogged radiator OR an air pocket in the system left over from your recent repairs will cause overheating more so at higher speeds.
You mentioned that you had no hot air when you selected the heater…this means there is no hot coolant flowing inside the engine, either a restriction in the radiator or air pocket is not allowing circulation or there is a leak and there is no coolant in the system.
When the engine is at normal operating temp you should not be able to easily squeeze together the upper radiator hose if there is plenty of coolant inside the system.
Hope this helps, keep me posted.


Austin Davis
Reader Follow Up
So I replaced the radiator and had a pressure test done for leaks in the system and there were none. and it is still over heating. And now a check engine light has came on and the code says that cylinder #2 is miss firing. I am getting flow through the system but I still am not getting hot air. What else could it be?
Hello Again John,
this is what I would do.

1. if you can feel an engine miss, then I would replace the #2 cylinder spark plug and wire (or ALL of them if they have more than 60K miles since their last change) see if this turns the check engine light off
2. focus on why your heater is not blowing hot air, there must not be enough hot coolant flowing through the engine and heater core located inside the dashboard
Both the radiator hoses should be pretty darn hot to the touch once the engine is at normal operating temperature, AND the two hoses going to the heater core…located on the passenger side firewall under the hood should be pretty hot.
if any of the hoses are much colder than the others, you have a restriction somewhere.
Once the engine is at normal operating temp the electric cooling fan should be cycling on and off as well
You should not be able to easily squeeze together the upper rad hose with your bare hands or there is a leak or not enough coolant
make sure all air has been bled from the radiator
Austin Davis
Posted in: Over Heating

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Austin Davis, consumer car repair advocate. "Hi there! I love to help people solve their car repair problems and I hope my site was helpful to you today. Thank you for stopping by."

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