Overheating issue

[Cfc]

A few weeks ago my 2007 Yaris started to overheat. Based on the issues I was having I changed the thermostat and water pump. I am still having the issue. The heater will not blow hot air and the car will still over heat. I can't find any leaks. I may also have air in the system. I have tried to allowing the car to run and adding coolant when the fan kicks on. Could air pockets be the cause? Any help is greatly appreciated.

[CTScott]

Air pockets could definitely be part of it, particularly with the heater core not working. There is a petcock on the back of the engine that must be opened when refilling the system otherwise a large pocket of air is trapped.

[Cfc]

Should I drain it. Open the petcock on the back and refill it. Or should I just open it now and try it?

[Exiwolfman]

A few weeks ago my 2007 Yaris started to overheat. Based on the issues I was having I changed the thermostat and water pump. I am still having the issue. The heater will not blow hot air and the car will still over heat. I can't find any leaks. I may also have air in the system. I have tried to allowing the car to run and adding coolant when the fan kicks on. Could air pockets be the cause? Any help is greatly appreciated.
What works well is leaving the rad cap off turn heat on full inside car and run car till u get heat from vents by leaving the rad cap off u will push out air out of the system, you may need to Rev the car up for a bit...this works well every time.

Sent from my Moto X Play

[CTScott]

Should I drain it. Open the petcock on the back and refill it. Or should I just open it now and try it?

If you open it now you will drain some fluid. I would put a pan under it, and open the petcock and let it drain until it stop from there. Then, start refilling the system until it starts to run out the petcock. Once it does, close the petcock, finish refilling and run the engine with the filler cap open until the bubbles stop.

If you fill the system without opening the petcock, no matter how much you run it with the cap open you will not get all of the air out.

[Cfc]

Do you have a link to a video or diagram of the petcock?

[tmontague]

^ya Scott, I'm curious as to what you find is the easiest method to access the petcock and what tool you use to open and close it.

To the OP, check the temp of your upper and lower rad hoses, could be a blockage of some sort not allowing heater core to heat up and/or not allowing fluid to fully circulate hence the over heat

[CTScott]

Do you have a link to a video or diagram of the petcock?

Here is a view of it from under the car. Once you understand where it is, you can easily access it from above. A 10mm socket is necessary to open it.

55964

[Yaristeve]

Is this petcock unique about this engine or do most modern engines have these now? I don't ever remember hearing/reading about such a petcock on older cars. And why wouldn't they put it on the head, at the highest point of the engine?

[CTScott]

Is this petcock unique about this engine or do most modern engines have these now? I don't ever remember hearing/reading about such a petcock on older cars. And why wouldn't they put it on the head, at the highest point of the engine?

I personally have only run into them on the 1NZ. I assume it is due to an issue where the path of water flow has a spot where air can collect and not be easily purged.

[ex-x-fire]

You could also purge air at the heater hoses, remember air rises. I like to use a heater hose pick.