My car is Overheating!

[Clindayen]

did the coolant look like it's flowing? and did bubbles emerge?

I saw very occasional bubbles, like every other minute it would bubble once or twice. I filled the radiator to the very top and the coolant sat there and never drained down. It also seemed to be still. Both hoses still did get hot though.

 

[Clindayen]

It doesn't leak does it ?

No leaks anywhere.

 

[20-CG5-01]

Seems as if the thermostat is stuck closed. Which thermostat did you go with?

I had a faulty autozone thermostat and replaced it with oem and it circulated fine.

 

[Chris Vu]

Check the under side of your radiator cap. There should be a little rubber thing that seals off the radiator once the cap is on. Make sure it's not cracked or missing. If it's missing, then the radiator loses pressure and that will cause the coolant to boil at lower temperatures which will make the coolant boil over into the overflow tank and from there it will leave as steam. That will explain why you lose coolant, and eventually will overheat.

Seems as if the thermostat is stuck closed. Which thermostat did you go with?

I had a faulty autozone thermostat and replaced it with oem and it circulated fine.

Thermostat should be fine if both hoses are heating up.

 

[Emphasis]

If there are no leaks, and the system was properly bled, it could be a faulty radiator cap as mentioned above.

Now I know you mentioned you replaced the cap. If the underside of the cap looks fine, What cap did you replace it with?

 

[001Stunna]

Your rad cap should look like either type D or F in this picture.

D if denso rad and F if Valeo rad i believe. No part/gasket/spring of that cap should be missing. In addition the cap should be rated/marked for 1.1bar or ~16psi

You mentioned you checked the oil dipstick and the color seemed normal. Try taking off the oil cap and look inside of it. Is there any white milky residue on the inside?

What color is the coolant in the overflow bottle and inside the rad? Is it green (or blue if OEM coolant) or is it creamy/milky?

Have you checked and verified there is no leaks? upper hose? lower hose? inlet/outlet hose to heater core? coolant hose behind engine(above oil filter)? any of the smaller coolant hoses going to the TB?
Any leaks will probably show as white spots, trace marks on the hoses as the coolant has dried.

I understand you already tried burping/bleeding the system but if wanted to give it another shot. Please make sure if you are spilling any coolant in the ground to wash it off with a lott of water or have a catch pan. Animals do tend to like it and can get harmed by it.
Now, to bleed the cooling system you need to start with a cold engine/car and while the car is still turned off...
-open the radiator cap and fill the radiator to the top with the proper coolant
-fill the overflow bottle in between of min and max
-leave the rad cap off, you can close the overflow bottle cap.
-start the car and let it idle
-inside the car set the dial to full hot and turn the fan on, a/c off.
-for the next ~10 minutes you will watch the radiator neck and top it off with coolant if the level goes down
-as you're watching give squeezes to the upper/lower rad hoses often to aid in releasing any air bubbles
-frequently go inside the car and look in the dash at the temp gauge to make sure the car is not overheating
-when you start seeing the coolant level to start rising and flowing out of the radiator and bubbles have stopped put the cap back on (do not worry if a bit spills over the rad as it overflows)
-now with the rad cap placed back on, let the car run until both fans come on (this usually happens when the temp reaches 95-96C)
-once verified that both fans come on, turn off the car.
-use adequate amount of water to clean any spills.
-retest/recheck if issue keeps happening

 

[Clindayen]

Check the under side of your radiator cap. There should be a little rubber thing that seals off the radiator once the cap is on. Make sure it's not cracked or missing. If it's missing, then the radiator loses pressure and that will cause the coolant to boil at lower temperatures which will make the coolant boil over into the overflow tank and from there it will leave as steam. That will explain why you lose coolant, and eventually will overheat.

My Radiator cap looks okay, has a bit of rust but no cracks or anything missing. Should I buy a new one anyways?

 

[Clindayen]

If there are no leaks, and the system was properly bled, it could be a faulty radiator cap as mentioned above.

Now I know you mentioned you replaced the cap. If the underside of the cap looks fine, What cap did you replace it with?

Sorry, what I meant was that after bleeding the system I put the original Rad Cap back onto the radiator. I might buy a new one just in case. It has a bit of rust on it.

 

[Chris Vu]

What you could always do too is let your car warm up and when it's at operating temperature, stand back and watch the coolant overflow bottle. If my theory is correct, you'll see coolant start to boil over and steam out of the overflow bottle's cap. Once that happens, just run and turn off your car. It'll definitely be a psi issue (or lack thereof) if that is the case.

 

[nsjames]

rust on the inside of the cap says to me that someone's been filling the rad with straight water.

I think the PO hosed you with a problem car.

i'd pull plugs and look for one that's exceptionally clean.
I'd also run it with the oil fill cap off and watch closely for steam.

mysteriously vanishing coolant+overheating screams head problem to me.

Of course, it could be a waterpump that's failed and is leaking as well.