My car is Overheating!

[mrnude]

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.

If it was the water pump you would be able to hear it on idle as well

 

[Clindayen]

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

I did this and it worked great, went on a 40 mile commute today and the car ran awesome! I'll update if the problem comes back. Thanks!

 

[Clindayen]

Well the problem hasn't come back BUT now it feels and sounds like the coolant in the upper radiator hose is boiling. A little rubber thing fell off my radiator cap, could this be the problem?

 

[Chris Vu]

Well the problem hasn't come back BUT now it feels and sounds like the coolant in the upper radiator hose is boiling. A little rubber thing fell off my radiator cap, could this be the problem?

Yep. Thats ecactly what ive been telling you. The little rubber thing seals the radiator which in turn raises the psi which also raises the temperature at which the coolant will boil. If the rubber thing falls off the radiator will lose psi which will cause the coolant to boil at much lower temperatures and cause what I explained in my earlier post. Replace your cap.

 

[Brad2274]

what have you been topping the radiator off with? id make sure you have a good mixture of water/antifreeze now because it boils at a higher temp and wont worsen your rust problem

 

[001Stunna]

what have you been topping the radiator off with? id make sure you have a good mixture of water/antifreeze now because it boils at a higher temp and wont worsen your rust problem

I'd go with deionized water if mixing it yourself, not tap water.

and change the rad. cap. Chris Vu alone has mentioned more than once to check it and change if anything missing from it.

 

[nsjames]

I'd go with deionized water if mixing it yourself, not tap water.

and change the rad. cap. Chris Vu alone has mentioned more than once to check it and change if anything missing from it.

this.

you can buy 2.5 gallons of water at the supermarket for like $3.

don't get spring water, you want deionized.

The key is not putting water with minerals in the cooling system. Leads to scale buildup and corrosion.