Possible stuck thermostat...

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?

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*

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Originally Posted by 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*

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

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

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

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Originally Posted by Thymeclock

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

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

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

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Originally Posted by petrified.rabbit

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

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

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Originally Posted by petrified.rabbit

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

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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

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.

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

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*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)

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Originally Posted by 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.


*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)

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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...

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Originally Posted by Pickles

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...

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

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.

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

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Originally Posted by Thymeclock

It sounds like the radiator is getting hot but the water isn't circulating through the radiator and back to the engine.

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fixed it for you :)

Those of you who work on VW's may remember the 2.0 and plastic water pump impellers. Here's a crosspost that may be helpful as it develops.

VWVortex.com - Temperature gauge reads hot when the engine is not overheating

*Flame suit on* :D

Ok, got everything replaced, now im HOPING the only problem is air in the system... Burped it as best as I could...
Currently, the car idles fine, perfect temp, fan comes on when it should etc.
When driving the temp will jump to 220 and the coolant will overflow. When I stop at a light/sign/ whatever it jumps back down to 190... my mechanic tells me this may be a bad head gasket... no white smoke, no oil in coolant, no coolant in oil... so im thinking otherwise...any suggestions?

would letting it sit and idle help with burping?

My experience with the '05 and '06 is that they burp very easily, without even raising the front-end way up. So, unless they changed the rad in the '10, I don't think that's your problem. JusteR already mentioned the block combustion gas test, which any decent shop can do (or you can buy/rent the tester and do it yourself). If no combustion gas shows up in the test, it wouldn't guarantee that you don't have a bad HG, but a positive gas test would unfortunately confirm bad news. I'm really puzzled that you're having problems like this on a fairly new vehicle - how many miles on it? Did you have anything else happen in the recent past that might explain this problem? Of course there can always be a bad part or factory assembly. Do you still have a drivetrain warranty?

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Originally Posted by JusteR

fixed it for you :)

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Um... no, not for me, as it's not my problem.

Still gotta fix the problem for the OP, don't we? :homework:
.

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Originally Posted by JusteR

Those of you who work on VW's may remember the 2.0 and plastic water pump impellers. Here's a crosspost that may be helpful as it develops.

VWVortex.com - Temperature gauge reads hot when the engine is not overheating

*Flame suit on* :D

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No disagreement, as it could very well be the problem. I had a Fiat once that had to be bled (burped) at the very top of the engine block once the system was opened and air was present in it. Actually the easiest way to do it was to fill it with fluid at that highest point.

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Originally Posted by avguy

My experience with the '05 and '06 is that they burp very easily, without even raising the front-end way up. So, unless they changed the rad in the '10, I don't think that's your problem. JusteR already mentioned the block combustion gas test, which any decent shop can do (or you can buy/rent the tester and do it yourself). If no combustion gas shows up in the test, it wouldn't guarantee that you don't have a bad HG, but a positive gas test would unfortunately confirm bad news. I'm really puzzled that you're having problems like this on a fairly new vehicle - how many miles on it? Did you have anything else happen in the recent past that might explain this problem? Of course there can always be a bad part or factory assembly. Do you still have a drivetrain warranty?

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I still have drive train warranty, so that's a plus... I don't know why I am having this problem either... the car is a 2010 with about 36500 miles

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Originally Posted by Pickles

I still have drive train warranty, so that's a plus...

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Was yesterday's t-stat work done by a dealer? How about oil changes? No first-hand experience myself, but I've read accounts where they tried to use ANY excuse to do the dealer dance and deny the claim.

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Originally Posted by avguy

Was yesterday's t-stat work done by a dealer? How about oil changes? No first-hand experience myself, but I've read accounts where they tried to use ANY excuse to do the dealer dance and deny the claim.

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Well, I know it isnt the head gasket... although something interesting... pulled the T-stat out of the old housing and everything.. its marked 105*... does that mean 221*f?! That is an insanely high temp for a tstat..

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Originally Posted by Pickles

Well, I know it isnt the head gasket... although something interesting... pulled the T-stat out of the old housing and everything.. its marked 105*... does that mean 221*f?! That is an insanely high temp for a tstat..

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I believe the tstat should be a 195*f, as most are. I could be wrong... some cars require a 185 or 205*f stat. As I stated previously mine runs 175 down the road in the winter(on the scanner not gauge,) I believe mine is staying open a crack... I digress... Long post to follow, be warned :)

When you pulled the stat, did it have the small air bypass valve with the bobbly-thing in it? Hopefully, yours had one and it was pointed in an orientation to help remove air (or other gasses.) Otherwise, air removal can be facilitated by drilling a 1/32" hole about 1/8" from the outer edge (or wherever convenient to allow air to pass around.) some race engine builders feel it's dangerous to drive without a stat, as this causes too much flow. I don't know if that's true or not, but I wouldn't let anyone catch me do that if I was trying to get an engine warrantied.

I've had success bleeding difficult cooling systems by using a vacuum refill kit, although others have said this vehicle isn't that difficult (haven't done mine or another Aveo yet-- but soon.) If you use a vacuum refill kit, please make sure you do it when the engine is Cold.

How soon after stopping does the temp go back down? I knew I had a problem with my intrepid because the fans would be on but the air coming out of them from the radiator was cool even though both hoses were hot. That would lead me to believe there is either a lack of coolant flow thru the radiator or gasses trapped in there.

I block tested my intrepid several times... People behind would flash their lights sometimes (getting splattered with coolant or smelling it?) but I never saw a color change in the dye tester. I even took the spark plugs out one by one and fed the cylinders air with the radiator cap off and nothing... I replaced a radiator, fans, tstat, and lower intake gaskets... still ate coolant. I am never a parts thrower where I work, but this thing had me at my wits end. Finally, one day I heard the mighty kaa-chunk of the starter kicking back. Pulled the plugs one by one and found the offending cylinder was full of coolant. pulled the plug out every morning and cranked it to relieve that cylinder. put it back in and Drove it like that every day for 6 months and junked it.

I don't wish that fate upon anyone, it's very frustrating as you can see. In order for heat transfer to occur, one needs pressure, surface contact, flow, and convection. I'm not sure if the fans go off above a certain speed, but I wonder if the A/C condenser is getting too hot or there is not enough airflow through both heat exchangers. On my best customers, I blow backwards with gentle compressed air or water to remove dirt and fuzz. Hands work good for determining hot and cold spots, non contact temp guns are a little better-- but those too have their limitations. I still gauge temps by hand at times and I believe 210 and over gives you a "ye-OW!" feeling. 180-190 gives you an "ow" and I think you get the rest. Unless a cold beverage has chilled your hand, then you can expect sensations to be exaggerated. :D

HTHY, good luck :)
Respectfully-- The Krusty Mechanic

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Originally Posted by Pickles

would letting it sit and idle help with burping?

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I know with Ford Taurus, they need a certain amount of air in the degas bottle (between full and low marks,) and the cap to stay on thru a few thermal cycles (operating temp, then sit until ambient temp, then operating temp) to get the air out. I try and vacuum fill those when my boss lets me. The old timers fear this new tool. afraid it may further damage weak spots in the cooling system. Although it beats letting an engine get really hot and then have coolant rush in when the stat opens imho... HTHY. I'm interested in how this pans out. Very sorry I don't know about Aveos specifically. Yet...

New radiator cap should arrive Wednesday. Air is all burped from the system, temp doesn't jump at all anymore but I am still having the overflow issue... if the cap doesn't solve it then I'm going straight to the dealer

Rabbit, I feel like an ass not listening to your first post here. Rad cap fixed it!!! Thanks for everyone who contributed you make this site a great place! :)

Pickles,
I appreciate the follow up + fix. Now some criticism:

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Originally Posted by Pickles

Ok, got everything replaced...

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Did you get a bad cap before? I assumed you replaced this already...

Either way, glad you fixed it. :)

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Originally Posted by JusteR

Pickles,
I appreciate the follow up + fix. Now some criticism:

Did you get a bad cap before? I assumed you replaced this already...

Either way, glad you fixed it. :)

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When I was saying that I was referring to the tstat+assembly. I can understand how that would be misleading though... I did buy an extra cap though to have a spare