So this is going to sound strange....

So lately its been near freezing out side, the cobalt is garage kept. But i start noticing a couple days ago that the Rad fan has been coming on more than usual. I wont really have to get on it at all and i usually dont when im just driving to work. they temp gets up to about 210-212 sometimes even 214. I would say it was the thermostat but the fact that the fan even turns on it cant be that right?

Anyway any input would be great!

 

t stats can screw up no doubt. Have you done anything to the cooling system lately.Airlocks are possible.Is the air dam in place? have you pressure tested the cooling system and rad cap? Is the coolant level changing at all? etc

 

No havent done anything to the cooling system...the coolant lvl is the same.. I havent checked the cap

 

Even if the thermo ***** up or stops regulating, the sensor will still kick on the fan iirc.... could also be just in need of a rad flush.

 

Alright got the car home drove with no heat on it got to 221 the fan was on the entire time..it cooled to about 212 - 216 when I got home I tried to burp the coolant system... took of the resvoir cap blasted the heat.. so it worked and the temp went down to 199-208. The fan cut off... I then tighten every turn off the heat it goes to 212 and sits the fan is on at about 208 . It sits there fan blasting like its not cooling a thing... and thats where I am

 

pressure test. get out of guesswork & get some data.

 

well i dont have any input for what could be wrong but i had the same iussue as you but it happened last winter.\

now ive figured it out...maybe lol i kept granny shifting. every time i drive home,id be cruising along in 5th gear at 55-60 mph and the rpm's are at 2200-2300 rpms and my temp level would bounce down to 196-205 constantly,and my fans would kick on! i read somewhere on here that granny shifting hurts more then helps. its been cooler here as well 15 degrees in the morning 25-30 degrees in during the day. this week when i was on my way home from work i would ride out 4th gear and that would keep me anywhere from 2700-3000 rpms (rush hour traffic,speed up,slow down,stop.) and my temps wouldnt get higher than 200 degrees. now i have 48k on my balt and was going to have the radiator flushed this spring since im about ready to park my cobalt.

my thoughts on this could be completley wrong but its only a theory and so far i have kinda figured out.

also check your radiator,where the air hits it. i had a bunch of cotton clog up a radiator on my work truck and it would over heat.

 

Well I did the same procedure I metioned before and everytime the coolant temp improved untill it got no lower about 190-200. I let run until the fan kicked on at 207... it cooled it back down to 199-200.. stayed... drove around fine. Ill see how this works

 

Is your car on the stock tune?

 

No its not byt tuned

 

Drove it furhter this morning, Im going to go with what Powell Said, I guess i need to start thorwing parts at it... Its like the Radiator is cooling...and or the fan isnt working

 

Not saying BYT is to blame for anything but get rid of his crappy tune lol

Anyway though just like powell said, pressure test.

 

Do our cooling fans have 2 speeds?

 

Ive also got a byt tune and my car runs pretty hot. The fan is almost always on after the car warms up. Even when its 30 out my car will hit 207 at a redlight. Usually i cruise around 200 degrees. My fan has never lowered my temperature only driving or coasting in 5th gear will lower the temp.

 

Did you ever find out what the problem was?

 

Nope, Im doing a cooling flush and changing the thermostat soon. We checked the rad, and the cap. Its been cold so the heats been on so no issues.

 

It could be something easy . . . like a bad thermostat cap.

 

^u mean rad cap

 

I'm having a very similar issue. My '08 SS/TC gets up to 210 degrees if I let it sit and idle for a few minutes. When I'm driving @ 55 or so, it runs @ 203- 205 degrees. My car normally runs at 194-198 degrees. I've had the engine block replaced before because it was burning up the coolant. I am @ 94k, but the car is my daily driver. It gets 115+ miles put on it daily. I did notice that "granny shifting" didn't really help much with the cooling, but The car still ran @ 203- 205 degrees @ 75 mph. I have to get my SS/TC checked out. Feels like I'm making payments on a ******* lemon now... kinda depressing.

 

U need a coolant flush and new tstat..happened to me..

 

Yes, I got thermostat happy.

 

Lemon is the middle name, Cobalt Lemon Chevrolet

 

Hahahaha. Chevy Cobalt "lemon" SS. I'd give 'er a flush just to see what that does... then maybe change the t- stat. My car normally runs between 194- 198 consistently, no more, no less. So it seems slightly strange that it'll start fluctuating( even though it sounds perfectly normal to do so)

 

I think people are going to start seeing a massive pile of people like my self flooding the threads with strange porous block issues. Or cracked blocks on the early casted LNF's 09 mostly.


Mine was 08/08/09 Sedan .... Seems to be a trend here. early models are failing now.

 

Not every block casted from early 09 is going to be porous. Perhaps some of them. But I'm sure your not going to all of a sudden see a ton of people with this issue all of a sudden. Most porus blocks showed up early in the cars life. Most people by now have 35,000 + miles on their car. And at that piont I would say it would be safe to assume that their block is probably fine.