Possible stuck thermostat...

[Pickles]

So last night, while my car was idling for a bit in my grandmas driveway, I noticed some steam coming from under the hood... Shut the car off, coolant surge tank is spilling over and out... WTF. Fill it with water, drive 1/8th mile home with heater on full blast for good measure and park it. did some testing today, tested antifreeze for tempature protection... I thought maybe it was boiling... its good for 222*. so thats fine. Felt the radiator hoses (not sure if I grabbed the right ones) grabbed the big ass one on the water pump, pretty hot... grabbed the little one on the bottom of the radiator... outside tempature. My coolant tank starts to overflow right at about 210*. Sound like a stuck t-stat?

[Pickles]

Ok, I was grabiing the PS line before... went out and checked again, both the bigass hose from water pump to radiator and the smaller one from radiator to surge tank are hot to the touch, yet the coolant still overflows at 209*

[Thymeclock]

Ok, I was grabiing the PS line before... went out and checked again, both the bigass hose from water pump to radiator and the smaller one from radiator to surge tank are hot to the touch, yet the coolant still overflows at 209*

How old is the car? Has the thermostat ever been changed?

Also: does the cooling fan come on when hot, or not?

[petrified.rabbit]

@ 210* would be the point of overflow if the system is not pressurized. Is the cap sealing properly?

[Pickles]

How old is the car? Has the thermostat ever been changed?

Also: does the cooling fan come on when hot, or not?

Fan doesnt come on till 215... I would loose tons of coolant by then. Its a 2010

@ 210* would be the point of overflow if the system is not pressurized. Is the cap sealing properly?

I believe so... it would overflow if the system wasnt sealed? it is leaking from the cap...

[Pickles]

@ 210* would be the point of overflow if the system is not pressurized. Is the cap sealing properly?

also, one thing to note, it doesnt slowly build up then overflow... the temp hits 210 and then coolant just rushes in through the hoses and causes it to overflow

[JusteR]

I chased an alleged blown HG for 2+ years (intrepid 3.5l) until my motor finally hydro locked. Had to pull a plug to start it after sitting. Get the CO2 sniffer with the blue dye and use it after you do the stat (but before you finish filling the coolant.) Hthy.

Stat = cheap
Engine = $$$

FWIW, My aveo runs around 175-180f at highway speeds. I prb have a stat that's stuck open or opens early. I'm sure you know to use the engine temp parameter and not the cluster gauge. Mine passes 2 bubbles thru the "de-gas" bottle every once in a while on a hot day. I'm probably headed for a new cyl head myself. Go with your gut tho, Petrified had a very good point.

@ 210* would be the point of overflow if the system is not pressurized. Is the cap sealing properly?

*Edit* Finally, I'd like to add that [gasses] air doesn't conduct heat as well as coolant, and sensors [or thermostats] in a gas pocket most likely aren't showing actual temp or anything close. --That goes for the fans too. What pressure does your system hold? What pressure does your cap hold? And if you know anyone who is an engineer; they'll tell you a lot about the properties of steam (I am not, TIC)

[Pickles]

I chased an alleged blown HG for 2+ years (intrepid 3.5l) until my motor finally hydro locked. Had to pull a plug to start it after sitting. Get the CO2 sniffer with the blue dye and use it after you do the stat (but before you finish filling the coolant.) Hthy.

Stat = cheap
Engine = $$$

FWIW, My aveo runs around 175-180f at highway speeds. I prb have a stat that's stuck open or opens early. I'm sure you know to use the engine temp parameter and not the cluster gauge. Mine passes 2 bubbles thru the "de-gas" bottle every once in a while on a hot day. I'm probably headed for a new cyl head myself. Go with your gut tho, Petrified had a very good point.


*Edit* Finally, I'd like to add that air doesn't conduct heat as well as coolant, and sensors in a gas pocket most likely aren't showing actual temp or anything close. --That goes for the fans too. What pressure does your system hold? What pressure does your cap hold? And if you know anyone who is an engineer; they'll tell you a lot about the properties of steam (I am not, TIC)

I do not understand any of this, or how it is relevant

CO2 sniffer with blue dye?
de-gas bottle?
And i have no way to test the system pressure...

[Thymeclock]

I do not understand any of this, or how it is relevant

CO2 sniffer with blue dye?
de-gas bottle?
And i have no way to test the system pressure...

That makes two of us who don't understand this.

You said that the fan does come on. What does the temp gauge read when this happens?

It sounds like the radiator is getting hot but the water isn't circulating through the cooling system. I'd suggest changing the thermostat. It's relatively cheap and easy to do. Then take it from there, if that doesn't solve it.

[JusteR]

De-gas bottle is what FoMoCo calls the pressurized tank where coolant is added. I used ford terminology on this one as a literary aid.

"Blue dye" sniffer= block tester. Commonly found at parts stores. Just like a pressure tester.

Without those tools you only know a part of the story. I will try to forgo cryptic posts in the future.

The Krusty Mechanic